The Amazon is the largest rainforest in the world, spanning more than 2 million square miles (5.2 million square kilometers) — an area 12 times the size of California. It influences global water cycles, stores years of global carbon emissions, supports 47 million people, and is home to the greatest concentration of biodiversity on Earth.

But the Amazon rainforest is also disappearing, with 17% of it already cut down or destroyed and largely replaced with agriculture. Other grave threats, such as oil drilling and illegal mining, continue to whittle it down. The next century may have outsize importance, as the forest could reach a "tipping point."

So what will the Amazon rainforest look like in 100 years?

The answer depends on a number of compounding threats, Bernardo Flores, a researcher with the EqualSea Lab at the University of Santiago de Compostela in Spain, told Live Science.

Encroaching farmland and organized crime are a couple of the problems chipping away at the Amazon. But those work in tandem with what he considers the three main threats: climate change, which can lead to extreme weather events, "like wetter wet seasons and drier dry seasons," deforestation and fire.

As the Amazon loses more of its forest, it triggers a feedback loop. "You have less rainfall; then you have less forest, [then] less rainfall, less forest," Flores explained. "That ultimately leads to "a global scale feedback involving the Amazon: More forest loss [leads to] more global warming. More global warming, more forest loss."

As forests get drier, it becomes easier for wildfires to burn more areas. Roads also degrade the forest, and "wherever you have roads, you have people doing illegal activities, illegal logging … then this leads to [more] forest fires," Flores said.

The "arc of deforestation" — a roughly 310,000-square-mile (800,000 square km) border along the Amazon considered the largest deforestation frontier in the world — offers a preview of what much of the Amazon could ultimately look like, according to Flores. The forests that remain there have higher tree mortality and more canopy gaps, and they are often "covered with lianas," or woody vines, that become an ecological problem, he said. Lianas compete with trees for light and nutrients in the soil, and significantly reduce not only a tree's chance of survival but also the overall diversity of trees in a forest. "When the whole forest is covered in lianas, you don't see the forest anymore," he added.

Invasive grasses introduced by cattle farmers will likely proliferate in the decades ahead, but "only a few parts" of the Amazon could become "a savanna, because a savanna is a native, biodiverse ecosystem," he said. Invasive grasses "exclude native species, reduce biodiversity" and would not allow native savanna grasses to replace the forest, Flores said. Instead, one possibility is a "degraded open-canopy ecosystem," where native, naturally fire-tolerant trees, combined with invasive grasses, vines and ferns, proliferate, Flores told Live Science.

Wildlife would quickly be affected as well. Aquatic species are especially vulnerable, Flores said. "When you start having these droughts that will simply last for one, two, three years," wetlands will dry out and become flammable, he explained. That could lead to "very quick extinctions in those areas."

The destruction of the Amazon rainforest would be disastrous for the Indigenous people living there, Christian Poirier, program director of Amazon Watch, an environmental and Indigenous rights advocacy group, told Live Science. "Imagine having your backyard bulldozed and your water source poisoned," he said. "You probably need to move from where you live, and that's exactly what's happening in the Amazon."

A devastated Amazon would also lead to "a more chaotic global climate system," Flores said. There could be less rainfall across parts of South America, and global warming will worsen. Earth could eventually reach a tipping point where ice sheets melt, ocean currents malfunction and the collapse of the Amazon accelerate warming all at once, pushing the planet to "cross the tipping point and transition to a much warmer climate," he said, leading to potentially irreversible consequences.

Unlike other major climate risks, such as the potential of the Greenland Ice Sheet melting and contributing to sea level rise, deforestation can in theory be reversed more easily by reforestation, said Arie Staal, an assistant professor of ecosystem resilience at Utrecht University in the Netherlands.

"That gives us a knob to turn that we don't have for other possible tipping points on Earth," he told Live Science. "It is clear that we really need to stop deforestation in the Amazon. And there's hope."

Editor's note: This article was updated at 6:23 p.m. EDT on June 22 to fix the conversion of roughly 310,000 square miles to 800,000 square kilometers.

Rainforest quiz: Can you sort the largest rainforests on Earth?

Climate change is pushing rice-growing regions into temperatures beyond those at which rice has been cultivated in the past 9,000 years of human history, new research finds.

Research suggests that warming is proceeding 5,000 times faster than rice has ever evolved.

This means rice may be reaching its "thermal limit," the point at which it can't easily adapt to rising temperatures. Although people can breed more heat-resistant strains or move rice cultivation into new regions, future warming is likely to cause serious disruption for the billion people who depend on rice cultivation for their livelihoods, said study first author Nicolas Gauthier, an anthropologist and geographer at the Florida Museum of Natural History.

"We don't want to downweight the flexibility of human adaptation," he told Live Science. "But we also want to acknowledge that these adaptations have already occurred, and in some cases, we might be closer to the limits of what we can reasonably adapt to in that time frame."

Rice is a staple crop for over half of the world's population, and 90% of cultivation occurs in Asia. Some rice-growing regions are already being hit by severe warming, which is affecting rice yields, according to the World Economic Forum.

Although rice is a heat-loving crop, rice photosynthesis shuts down at around 104 degrees Fahrenheit (40 degrees Celsius), and too much heat can also affect pollen viability and grain growth. Rice is also a water-intensive crop, so shifts in the wet and dry seasons are a problem, as is sea-level rise because low-lying paddies may become inundated with salt water, which can kill the crop.

Gauthier and his colleagues gathered data on past climate from archaeological sites where scientists have found evidence of rice cultivation over nearly a millennium. They found that rice has often expanded into cooler regions as humans have bred cold-tolerant plants and adjusted their agricultural practices. But, he added, the upper temperature limit has stayed the same since the beginning of rice cultivation about 9,000 years ago.

In the history of rice farming, cultivation has remained limited to places where the mean annual temperature is below 82.4 F (28 C) and the maximum temperature in the warm season stays below 91.4 F (33 C), on average, the researchers reported in the journal Communications Earth & Environment.

Climate change might warm regions where it is currently too cool to grow rice, enabling a geographical shift in cultivation, Gauthier said, but there will be challenges. Rice paddies have been built up over centuries, and it's not easy to "just pick up and move," he said. And the disruption in rice cultivation will have major economic and food security impacts, he said.

"You could keep global rice production the same" by moving cultivation around, he said. "But that's not fixing the problem for people who live in South Asia who are relying on rice for their consumption."

Editor's Note: The headline of this story was changed at 10:45 a.m. EDT on May 23 to better reflect the current study's findings.

Over the past two decades, some studies have suggested that human brains are shrinking. But there is also evidence that IQ scores have risen over the past century.

But is it possible for us to get smarter as our brains shrink? Live Science contacted experts to find out.

First, it's important to note that a bigger brain size does not necessarily mean higher intelligence, said Jeremy DeSilva, an anthropology professor at Dartmouth College. Brain size "is only weakly related to measures of intelligence in humans. Albert Einstein's brain, for instance, was quite small, and he was Einstein!" he told Live Science in an email.

In Einstein's case, it appears that extraordinary folding patterns in several of his brain regions may help account for his genius. While there is some debate, studies suggest that there is little or no relationship between our intelligence and brain size in humans.

Have human brains shrunk?

Not all scientists agree on whether human brains have gotten smaller. However, many experts we spoke with said there is evidence for shrinkage over time.

"My research indicates that human brain size declined during the [entire span of the] Holocene by about 10% of its volume or about 150 ml on average," Maciej Henneberg, a professor emeritus of anthropological and comparative anatomy at Adelaide University in Australia, told Live Science in an email. The Holocene is an epoch that followed the last ice age, and spans from 11,700 years ago to the present day. In his research, Henneberg looked at the brain size by analyzing skulls from all over the world. In many cases, he analyzed the skeletons personally.

It's important to remember that Homo sapiens emerged around 300,000 years ago, so a brain shrinkage starting around 11,700 years ago would be a relatively recent development.

Other scientists have reported similar findings. "Our lab thinks that the data currently available show a clear, global trend toward a decrease in brain size in more recent times," said DeSilva, whose research looked at more than 5,000 skulls from people who lived in Europe, Asia, Africa and Australia. Many of the skulls date to the Holocene.

Jeff Stibel, who holds a doctorate in brain science and has published a number of papers on the topic of brain shrinkage, said the "Holocene warming period has coincided with more than a 10% reduction in brain size in modern humans." Stibel took part in DeSilva's research, and then gathered more data by analyzing the brain size of roughly 800 additional skulls from around the world.

However, some scientists disagree. Research by Brian Villmoare, an associate professor of anthropology at the University of Nevada, Las Vegas, and his team found no evidence that human brains are shrinking. "I see no evidence that, once we acquired our modern form, that our brains have changed in any meaningful way," Villmoare said in an email.

Some say more nuance needs to be considered. "Brain size in some human populations decreased over the last 15000 years," John Hawks, an anthropology professor at the University of Wisconsin-Madison, told Live Science in an email. "But there are some complexities."

Hawks noted that datasets of brain size tend to overrepresent men of European ancestry, making it difficult to determine whether there is a global trend among diverse populations.

"Brain size did rebound toward larger sizes during the last 150 years in industrializing countries," Hawks said. "This was likely mostly attributable to nutrition and correlated with body size, but whether body size accounts for the entire effect is not clear from the limited data."

Why are human brains getting smaller?

If our brains have shrunk, then why? Scientists have proposed a few ideas.

One has to do with the introduction of farming.

"During the Holocene, humans gradually introduced food production [such as agriculture and animal husbandry] that allowed them to live in larger communities," Henneberg said. "The brute physical strength required for hunting big game and protecting families against strong predators became less necessary while a smaller body size required less food, so it was favoured by natural selection."

In fact, it's not just our brains; our bodies have also shrunk. "At the end of the Ice Age, male body height was about 1.75 m [5.74 feet], whereas in mid-Holocene agricultural communities it was 1.65 m [5.41 feet]," Henneberg said. "Body mass has declined even more since we see thinner (less robust) human bones." Heights have rebounded recently in some parts of the world, and Hawks said that our brain sizes may be rebounding also.

The warming that occurred after the end of the last ice age also may be a factor. Stibel said two biological principles, known as Bergmann's rule and Allen's rule, state that "bodies and organs tend to become leaner in warmer climates to increase surface area and dissipate heat."

Another possible explanation is that human intelligence itself has changed as we have taken on more specialized jobs and share more information with each other, meaning we don't have to know everything, just a subset of knowledge to keep society going.

DeSilva said his team proposed that a "population increase, the subsequent specialization of people into specific roles in society and the growth of collective intelligence may have contributed to individual brain size decrease as modeled in some eusocial insects like ants and wasps." For instance, "I'm a decent enough anthropologist and anatomist, but you wouldn't want me fixing your car or investing your retirement savings on Wall Street."

Stibel agrees that this is a significant factor. "Some ant species that develop complex social systems see similar reductions in individual brain size as the colony carries more of the cognitive load," he said. "We appear to have done something remarkably similar with culture and technology.

"What our research suggests is that we've undergone a fundamental shift in how cognition works," Stibel added. "Rather than relying solely on individual brainpower, we've become extraordinarily dependent on cultural and technological networks."

Stibel noted that large brains can be a burden, consuming more energy which requires people to eat more food to survive. "Large brains are metabolically expensive, consuming roughly 20% of our resting energy and producing significant heat." During times when food is scarce, such as during an Ice Age, this can result in people with larger brains being more likely to die of starvation.

This doesn't mean humans are smarter or dumber than they were; it just shows our intelligence is different.

"We've likely traded some raw computational capacity for the ability to leverage collective intelligence," Stibel said. "Whether that's a gain or a loss depends entirely on how you define intelligence. And, of course, how stable the cultural and technological systems we now depend on turn out to be in the long run."

See how much you know about the most complex organ in the human body with our brain quiz!

As the planet warms due to climate change, extreme heat is threatening global food security by harming crops and livestock and reducing the number of hours farmers can work.

A recent report by the U.N. Food and Agriculture Organization and the World Meteorological Organization warned that the impacts of extreme heat are pushing agricultural systems to the brink. The agencies found that half a trillion working hours are lost due to extreme heat each year — and the impacts will only worsen as global temperatures continue to climb.

The U.N.'s warning came the day after the Lancet Countdown ‪—‬ an international research collaboration that monitors key indicators of health and climate change ‪—‬ published its own report on health and climate change in Europe. Among its findings, the report highlighted that climate change is already causing heat-related deaths, unsafe working hours and food insecurity.

Live Science spoke with Shouro Dasgupta, an environmental economist and a co-author of the Lancet Countdown report, about extreme heat and agriculture in the wake of the new reports. Here's what he had to say.

Patrick Pester: How does extreme heat impact food production?

Shouro Dasgupta: Our crops are productive when the temperature is within a certain range. With extreme heat, we often see this range being breached. The other part is that, with high heat, crops wither, so many of them don't even get close to being harvested. Those are the two most common extreme heat impacts. Drought is another one. In many parts of the world, we now see prolonged droughts or droughts unprecedented in the history of that region.

PP: What does the U.N. report reveal that we didn't know already?

SD: This report is more for synthesis. It brings together the body of knowledge that currently exists, and it also focuses on several aspects of crop production. There are numerous case studies from all over the world — from the impact of heat on certain types of crops, all the way to livestock. It has a very detailed chapter on livestock, which is often not as well researched as crops.

PP: So animals aren't as productive when it's hot?

SD: Exactly, and it's dangerous for their health. For millions of farmers, their livelihoods and income depend solely on livestock, and as extreme heat generally kills livestock around the world, it's not just the supply of food that is being affected, but at a very human level, the livelihoods of these farmers are being destroyed.

PP: And it's going to be harder for farmers to work if it's very hot.

SD: It reduces their productivity because they have to take frequent breaks to protect their health, which brings us to the fact that agricultural workers also tend to have the least amount of social protection. They don't usually have contracts, and for millions of agricultural workers, unless they're working, they're not earning anything. So they often have to sacrifice their health in order to keep working.

PP: You published your Lancet report the same week as the U.N. report was released. What's different about your report, and what have you found?

SD: The Lancet Countdown is focused on indicators. Two of the indicators are very relevant to the discussion we're having. The first one is the impact on food insecurity in Europe, which is access to food. Our results show that compared to the 1981 to 2010 baseline, a higher frequency of heat waves and droughts has resulted in 1 million additional people becoming food insecure in 2023 alone. So the message is, food insecurity is no longer just about low-income countries. This is happening now in Europe.

The second indicator that I want to mention is the impact of warming on high-exposure sector workers. This is where we focus on working hours in agriculture and construction sectors in Europe. Our result shows that, due to warming between 2020 and 2023, on average, warming has resulted in a reduction of 24 hours per worker per year ‪—‬ so workers are having to reduce their working hours to protect their health. When they reduce their working hours, they earn less, which affects their livelihoods. And when they earn less, the profits of the company or the farm they work for also declines. This is transmitted to lower output and, eventually, lower economic growth.

PP: Is everyone going to be impacted by this if it's a global issue?

SD: At some point, yes. There is a lag between shocks on the workforce and the price we pay in the supermarket. But eventually, these impacts will be transmitted through the supply chain. At the same time, food production itself is being affected by extreme heat, and the joint effect of this results in increasing prices.

PP: How do we address this? Can we address this?

SD: Yes. I think it's important that we give a positive message.

There are policies that can be implemented to protect the agriculture sector and agricultural workers — safety nets. By safety nets, I mean proactive safety nets. We need to anticipate food insecurity events before they become famine. And safety nets — whether in the form of cash benefits, cash transfer or food assistance — have to be anticipated. We can no longer rely on reacting after an event has taken place.

Other policies, especially in the agricultural sector, would be investing in climate-resilient crops and salinity-resilient crops. In these cases, there can actually be learning from Global South to North. Countries such as Bangladesh, where I'm from, have more than three decades of experience in developing climate-resilient and salinity-resilient crops.

Editor's note: This interview has been condensed and edited for clarity.

The risk of malaria influenced where prehistoric people lived in sub-Saharan Africa, a new study suggests.

The research is the first to link early human habitation with the deadly disease and contrasts with early assumptions that prehistoric people migrated to different regions mainly for agricultural reasons.

In the study, researchers analyzed existing models of climate and environmental data that indicate where malaria was likely prevalent, and compared it with maps of early human settlements. They found that prehistoric humans seem to have avoided regions where malaria was endemic long before the introduction of farming in sub-Saharan Africa between about 3000 and 1000 B.C.

"For a long time, it was thought that infectious diseases only really became a problem with the advent of farming, and this was particularly true of malaria," study co-author Eleanor Scerri, an archaeological scientist at the Max Panck Institute of Geoanthropology in Germany, told Live Science in an email.

But the study by Scerri and her colleagues, published April 22 in the journal Science Advances, suggests that humans have avoided settling in areas with a high risk of malaria for more than 70,000 years.

"Our work shows that we can no longer ignore diseases in the deep human past," she said. "They don't just have a small effect, they have — in the case of malaria, at least — transformative impacts that have helped to shape who humans are today."

Malaria risks

The study authors used data from earlier studies to reconstruct the climate of sub-Saharan Africa over the past 74,000 years in intervals of between 1,000 and 2,000 years.

Then, they calculated a "malaria stability index" for each area at every step, based on modern epidemiological data and the likelihood that an area contained habitats for the Anopheles genus of mosquito. The bites of female Anopheles mosquitoes transmit the parasite Plasmodium falciparum to humans, which causes malaria.

By comparing this index to maps of early human settlements, the authors showed that prehistoric hunter-gatherers in sub-Saharan Africa had actively avoided high-risk malaria hotspots. The researchers said that this behavior, in turn, helped determine human population structures by at least 13,000 years ago — several thousand years before the introduction of farming.

"The key message from our paper is that malaria was already a bit of a problem before agriculture," study co-author Andrea Manica, an evolutionary ecologist at the University of Cambridge, told Live Science. But "it likely became even worse after people became sedentary and settled at high density as a consequence of food production."

The study suggests that Central West Africa was hardest hit, he added, and the region remains a malaria hotspot today.

"Archaeology in Central West Africa is limited, but a number of findings agree with a view that populations in this area were highly fragmented," Manica said.

Malaria hotspots

The study is the first to suggest that the locations of prehistoric human settlements were influenced by the risk of disease, rather than just changes in the climate — although both rainier and warmer weather would have encouraged populations of disease-carrying Anopheles mosquitoes.

"The role of disease in the deep human past, particularly in the earliest, African phases of our species' prehistory has not been well investigated because we lack ancient DNA from those time periods," Scerri said.

But the new study showed how the lack of evidence could be overcome. "We have developed a pipeline that is capable of exploring a number of vector-borne diseases," Scerri said. "It's an exciting breakthrough and we hope it will open up a new field of inquiry."

"We have shown that it is possible to track a disease back in time and assess its potential impact on past inhabitation," Manica added. "The next phase is to start exploring other diseases besides Plasmodium falciparum to see their role."

Simon Underdown, a biological anthropologist at Oxford Brookes University in the U.K., who was not involved in the new study, said he agreed with the study's conclusions.

"Disease has always been with us, and it actually shaped what humans could do, where humans could move," he told Live Science.

See how much you know about early humans with our human evolution quiz!

Catastrophic water shortages are in store for the 40 million people living in areas fed by the Colorado River, even if cities in the region such as Denver, Phoenix and Las Vegas make dramatic cuts to their usage, recent research suggests.

Water shortages could start as soon as this summer, as snowpack levels reached a record low over Lake Powell and the spring runoff into the Colorado River is expected to be minimal, experts told Live Science. And the region's major cities, which have already slashed their per capita water consumption by up to 58% between 2002 and 2025, can't solve the problem alone.

"We can't just shove it all onto the residents of these cities and tell them to use less water, because it's still not going to be enough [to prevent water shortages]," Renee Obringer, an assistant professor in the Department of Energy and Mineral Engineering at Penn State and the first author of the new study, told Live Science. "Regardless of what mitigation we do, we're still going to have to adapt to this warmer world that is going to have more intense droughts and more frequent droughts."

The findings reveal that bolder measures will be needed to head off disaster in the Colorado River basin. But exactly what are those steps?

One piece of the puzzle

Seven states — Arizona, California, Colorado, Nevada, New Mexico, Utah and Wyoming — pull water from the Colorado River, and the amount allocated to each region is governed by a century-old document called the Colorado River Compact.

But the Colorado River basin, along with the rest of the U.S. Southwest, has been in a megadrought for 25 years. Between 2000 and 2019, the river's flows shrank by 20% due to climate change and water overuse to supply cities, agriculture and industry.

Finding new water supplies is unlikely, so Obringer and her colleagues analyzed what would happen if three large cities fed by the river — Denver, Las Vegas and Phoenix — reduced their consumption by around 25% under various climate scenarios, ranging from a global temperature increase of about 2.9 degrees Fahrenheit (1.6 degrees Celsius) to an increase of 7.7 F (4.3 C) compared with preindustrial levels.

Their results were published in December 2025 in the journal Water Resources Research. In most climate scenarios, demand management — which encompasses broad strategies such as raising awareness, offering rebates, and subsidizing low-flow devices — did not make up for lower water storage in urban reservoirs caused by higher temperatures and lower precipitation in the region. Denver, which is technically not located in the Colorado River basin but gets half of its water from the Colorado River, was the lone exception. Demand management compensated for river flow reductions in two high-emissions climate scenarios for the city. However, Obringer suspects some of those more optimistic results could be an artifact of the way the model handles uncertainties.

Cities fed by the Colorado River basin have reduced water use through programs aimed both at demand and reuse. In Las Vegas, for example, residents receive cash rebates for replacing water-heavy lawns with desert plants. The city, which gets 90% of its water from the Colorado River, also returns, after treatment, 40% of the water it uses to Lake Mead, where it can then be reused.

Cities have taken significant steps to reduce their footprint, and they will likely continue to improve, said Brad Udall, a senior water and climate research scientist at Colorado State University’s Colorado Water Center who was not involved in the study. As a result, some of the region's biggest cities use less water per capita than they did a few decades ago.

But the more efficient cities get, the fewer opportunities they will have to save and reuse water, Udall told Live Science.

Bigger water users

The results highlight a reality scientists have long known: Demand management alone cannot offset the Colorado River's dwindling flows, said Sharon Megdal, a professor and director of the Water Resources Research Center at the University of Arizona, who was not involved in the study.

Cities make up only 18% of water use in the region, while agriculture guzzles more than 70% of the basin's water. "Agriculture's the big user," Megdal told Live Science.

"You can't solve this problem without dealing with agriculture in a major way," Udall agreed. "Because agriculture is 70% of the problem, it needs to be at least 70% of the solution."

Individual farmers have senior water rights to Colorado River water, meaning they receive their full allocation regardless of whether there is a shortage, but political pressure is rising to allocate more water to cities and cut farmers' consumption, Udall said. For example, water managers may decide that farmers in Arizona have to relinquish water to supply the Central Arizona Project canal, which delivers water from the Colorado River to the central and southern parts of the state, including Phoenix and Tucson.

Since 2019, the Colorado River has shrunk so much that it is now 35% smaller than it was on average in the 20th century. "We've never seen flows like this," Udall said. "If these flows continue to drop, I do see agriculture in the Lower Basin not getting the supplies they do [now] and those supplies being reallocated to cities."

The problem is that farmers in the Lower Basin grow crops that benefit the region economically through exports, including alfalfa, cotton, vegetables and citrus fruit. In Arizona, roughly 20% of cropland is used to grow alfalfa for cattle feed. The state is also the biggest cotton producer in the Colorado River basin, and it grows up to 90% of leafy greens consumed in the U.S. and Canada.

To cut their water consumption, farmers can change their irrigation techniques and crop patterns, Megdal said. Drip irrigation, which delivers water directly to the roots, cuts evaporation and reduces water use by up to 50% compared with methods such as flood irrigation used for cotton and alfalfa. Thirsty crops such as alfalfa could be replaced with low-water forage mixes consisting of wheat, barley, oats, rye and peas. Recently, there has also been a focus on guayule, which is a substitute for rubber, as an alternative crop for farmers, Megdal said.

But farmers respond to demand and may have long-term contracts with buyers. "It has to be economical," Megdal said.

Agriculture should switch to more efficient irrigation, but it's also important to realize that some seemingly wasteful methods, such as furrow or flood irrigation, can replenish aquifers, which are also being depleted, Udall said.

Some farmers are letting their fields go fallow, which could happen more and more as water shortages intensify, Megdal added.

Renegotiating water rights

The Colorado River Compact is up for renewal this year, meaning there is an opportunity to devise a more sustainable agreement, Obringer said. But negotiations have stalled between the Upper Basin, which includes Colorado, New Mexico, Utah and Wyoming; and the Lower Basin, which encompasses Arizona, Nevada and California. While officials wrangle over the precise wording in the document, the underlying problem is that the Lower Basin needs more water than it's getting, even though the Upper Basin already uses less water than it was allocated in the compact.

Officials in the Upper Basin have argued that cuts should now fall exclusively upon the Lower Basin. But that can't happen, Udall said, because cuts need to be deep across the Colorado River basin to make a difference. No matter what the Upper Basin thinks it is entitled to, it must accept reductions in water use, he said.

Reality check

Solutions must be found and implemented immediately, because the Colorado River's future has never looked bleaker.

Winter brought barely any snow, and the little that fell melted in early March instead of April, meaning river flows this spring and summer could hit record lows. "It's unprecedented; it's human-caused; it's scary, frightening, awful," Udall said.

Udall estimates that Lake Mead, which serves almost 25 million people in cities such as Las Vegas and Los Angeles, and Lake Powell, which supplies Lake Mead and Indigenous tribes, will be only about 20% full over the coming months. Without adjustments in reservoir release, water levels could drop low enough to prevent energy production at Glen Canyon Dam, which usually produces enough electricity to power over 350,000 homes.

"We're close to dead pool," Udall said. This is when the water level in a reservoir falls so low that it can't flow downstream. "That's never happened, and it's very serious."

It would take years of unusually high precipitation and runoff to recover from the current state, according to Megdal. "It is a challenging situation," she said. "You really have to adjust to a new normal."

To make matters worse, "data centers are popping up everywhere in this region," Obringer said. A midsize data center uses up to 300,000 gallons (1.4 million liters) of water per day for cooling, and this number will only increase as temperatures rise. Much of the water that runs through the system can be reused, but some is consumed to generate the electricity to power data centers.

Some small steps to mitigate the problem are already in the works. Some municipalities are buying water rights and groundwater from rural areas in the region, Megdal said. For instance, the rapidly-growing town of Queen's Creek, Arizona, is purchasing groundwater from farmers and investors in the sparsely populated Harquahala valley. Arizona is also drawing up agreements with California and Mexico to obtain desalinated water.

"I do think there's a tremendous capacity to adapt," Megdal said.

But a more durable solution will require a major overhaul of the existing agreements and water rights to reflect reality, Udall said.

"We've got to have an agreement on how to share the water we have and not pretend we live in the past," he said. "We need to adjust this system to deal with a completely new reality of much less water flow. We've got to balance the books here."

Bird populations are in free fall across North America. And in some hotspots their decline is accelerating, a new study reveals.

Wild bird numbers declined at an accelerating rate in California, the Midwest and the Mid-Atlantic between 1987 and 2021. Across these hotspots, losses were associated with high-intensity agriculture, according to the study.

Although the study, published Feb. 26 in the journal Science, shows a correlation between declining bird populations and intense agriculture, it doesn't definitively prove that agriculture is driving the increased decline or identify which agricultural activities might be responsible.

However, signs of intense agricultural activity consistently proved to be the best predictor of increased bird decline, which mirrors similar research conducted in Europe. The researchers also found that declines were stronger in warming areas, suggesting that rising temperatures due to climate change were driving some bird disappearances.

Birds perform important roles in the ecosystem, including spreading plant seeds and keeping insect populations under control. For decades, scientists have been concerned that bird populations are falling due to human activities, both in North America and globally — a plight shared by many other animals. What's special about the new research is that it reveals how the decline in North America has accelerated since the late 1980s.

"We are not talking about the decline but the acceleration of the decline," study lead author François Leroy, a postdoctoral researcher in macroecology at The Ohio State University, told Live Science. "We see that this decline is getting faster and faster with the intensification of human activities."

Leroy and his colleagues mapped bird decline by studying data from the North American Breeding Bird Survey, which is an annual surveying effort by professional biologists and skilled amateurs to monitor bird populations across North America. As a part of the survey, participants walk along specific routes and record the birds they find.

The researchers focused on specific routes with enough data to measure the rate of decline over 35 years. These routes were primarily in the U.S. and included 261 bird species. Across all of the species surveyed, the overall abundance of birds fell by at least 15%, with significant drops documented in about half (122) of the species and accelerating declines reported in about a quarter (63) of the species. Common birds ‪—‬ like red-winged blackbirds (Agelaius phoeniceus), house finches (Haemorhous mexicanus) and American crows (Corvus brachyrhynchos) ‪—‬ were among the native species found to have suffered an accelerated decline.

The study focused on the rate of decline in specific routes, so it's unclear how many individual birds were lost across the entire continent during the study period. However, previous research has found that billions of birds have disappeared in recent decades.

A 2019 study published in the journal Science estimated that the North American bird population decreased by 2.9 billion individual birds between 1970 and 2017. That estimate equated to a drop of 29%, which is almost double the 15% decline documented in the new study. However, the 2019 study also covered an earlier and longer time period when there may have been more severe losses.

People only started surveying North American birds in the second half of the 20th century, but we've been killing them directly and indirectly for much longer than that. For example, commercial hunting by humans forced passenger pigeons (Ectopistes migratorius), a species estimated to have once had a population of 3 billion to 5 billion, to extinction in 1914.

What caused the "birdemic"?

The new study demonstrated that birds were incurring losses not just at the species level but across whole families of species and across different habitats. To better understand the worrying trend, the researchers compared the bird data to potential contributing factors, such as temperature change, rainfall and land-cover changes.

The acceleration of bird decline coincided with large areas of croplands and high usage of fertilizers and pesticides, which are signs of intense agriculture. This tracks with research in Europe that has found that agricultural intensification has negatively impacted bird diversity.

Intense agriculture can destroy, change and break up traditional bird habitat. The amount of land used for farming in the U.S. hasn't changed that much since the 1980s. Agriculture has become more consolidated in that time, with a decline in midsize farms and a shift to larger farming operations, but there's slightly less land being used for farming overall. Thus, the bird losses can't be blamed solely on the amount of farmland. However, they could be the result of changes in farming practices.

Leroy said that from the new study, it's not really possible to say which specific practice in agriculture is the worst for bird losses. However, he noted that from previously published studies, it seems like pesticide use is one of the main suspects.

A 2023 study published in the journal PNAS found that the use of pesticides and fertilizers was the key to agricultural intensification being the main pressure behind most bird population drops, particularly in birds that feed on invertebrates. Most disappearing bird species depend on insects for food, and insects are in steep decline as they are killed through the use of pesticides. Birds also consume pesticides directly.

Leroy said he would like to see what farmers think about the correlation between agricultural intensification and bird losses. He and his co-authors also noted in the study that agriculture warms landscapes by reducing the amount of vegetation and altering its properties, which may then amplify warming impacts on birds.

While the findings were mostly bad news for birds, there were some bright spots. For example, the researchers found some local increases in forest bird populations, which likely benefited from the reforesting of old farmland. There was also a small pocket of land just north of the U.S.-Canada border where the overall abundance of birds increased — the only region in which this occurred. However, Leroy said he had "no clue" why this was the case.

"It doesn't mean that Canada is doing better because if you look at other regions in Canada, there were also some significant declines," he added.

The U.S. government has officially resurrected the food pyramid — and flipped it on its head.

The new food chart emphasizes meats, dairy and what it calls "healthy fats," as well as fruits and vegetables. It accompanies new nutrition guidance that upholds some well-established diet recommendations while breaking with others.

The Departments of Agriculture and Health and Human Services released the new dietary guidelines on Wednesday (Jan. 7), and in doing so, they retired MyPlate, a visual guide to healthy eating that replaced the food pyramid in 2011. The so-called New Pyramid is an inverted triangle with protein, dairy and "healthy fats" at the top, alongside vegetables and fruits. At the bottom of the flipped pyramid are whole grains.

The brief guidelines accompanying the New Pyramid place a heavy emphasis on avoiding highly processed foods, refined carbohydrates and added sugars, noting that the unrefined sugars found in foods like fruit and milk are not considered "added."

The guidelines also specify that healthy fats include those found in meats, poultry, eggs, omega-3–rich seafood, nuts, seeds, full-fat dairy, olives and avocados. Olive oil (mostly unsaturated fat) and butter and beef tallow (mostly saturated fat) are listed as good options for cooking oils. That said, the guidelines don't change the long-standing guidance about limiting one's consumption of saturated fats, stating that they should not exceed 10% of a person's total daily calories.

The guidelines significantly increase recommended protein intake, NBC reported. Established guidelines say that 0.8 grams of protein per 2.2 pounds (1 kilogram) of body weight would meet the daily nutrition requirements of the average, sedentary adult. Higher amounts are recommended for physically active adults (about 1.1 to 1.5 grams per kg) and older adults (about 1 to 1.2 grams per kg).

The new guidelines recommend a baseline daily protein intake of 1.2 to 1.6 grams per kilogram of body weight. So for a 150-pound (68 kg) person, that's a jump from 54.4 grams of protein a day to about 81.6 to 108.8 grams.

Health Secretary Robert F. Kennedy Jr. had delayed releasing new dietary guidelines for months after rejecting the work of a 20-person scientific advisory committee assembled under President Joe Biden, STAT reported. The committee was poised to recommend plant-forward diets, rather than meat-centric ones, and had concluded that the existing research on ultraprocessed foods was inadequate to develop clear recommendations.

(The definition of "ultraprocessed" can be difficult to pin down, and while many experts agree ultraprocessed foods are unhealthy to eat in excess, it's hard to know if every food under the ultraprocessed umbrella carries the same health risks.)

The new guidelines, meanwhile, put a notable emphasis on meat and dairy and say to avoid highly processed foods, without clearly defining what "highly processed" means. They do say to avoid packaged, prepared and ready-to-eat meals; foods that are salty or sweet; sugar-sweetened beverages; and foods containing artificial flavors, or preservatives, or low-calorie, non-nutritive sweeteners.

Some experts worry that the guidelines' emphasis on meat and dairy — including the notable inclusion of steak, ground beef and a carton of full-fat milk on the illustration of the inverted pyramid — may promote high intakes of red meat and dairy products. This "will not lead to optimally healthy diets or a healthy planet," Dr. Walter Willett, a professor of epidemiology and nutrition at Harvard T.H. Chan School of Public Health, told CNN in an email.

"These guidelines recommend heavily meat-based diets — protein is a euphemism for meat," Marion Nestle, a nutritionist and professor emeritus at New York University, told STAT via email.

MyPlate previously sorted foods into five categories — fruits, vegetables, grains, protein, and dairy and fortified soy alternatives — and provided general recommendations for how much food a person should eat from each category based on their age and sex. As a rule of thumb, fruit and vegetables made up half the plate, and proteins and grains comprised the other half, with a small amount of dairy featured on the side. Healthy oils were defined as vegetable oils and those found in seafood and nuts.

MyPlate also emphasized that additional factors beyond age and sex — such as height, weight, physical activity levels, and whether you are pregnant or breastfeeding — may affect daily nutrition needs. About 150 pages of guidelines detailed those nuances, and also set specific intake limits on added sugars, saturated fats, sodium and alcohol.

The new guidelines also acknowledge that a person's nutrition needs may vary depending on various factors, and they provide some brief guidance for specific populations, such as infants, pregnant and lactating women, and older adults.

They don't note a specific limit for daily alcohol intake, instead saying that people should generally "consume less" for better overall health. They also specified groups, such as pregnant women, who should avoid it altogether.

They added that those with a "family history of alcoholism [should be] be mindful of alcohol consumption and associated addictive behaviors." (While genetics do play a role in who is vulnerable to alcohol use disorder, genes are not the only factor at play, and people without a family history can also develop the addiction.)

These national dietary guidelines influence what's included in school lunches and military meals, as well as federal food assistance programs such as the Supplemental Nutrition Assistance Program (SNAP), NBC reported. A White House spokesperson said the new guidance will be phased into schools and federal food programs over the next two years.

This article is for informational purposes only and is not meant to offer medical or dietary advice.

Earth's continents are drying up at an alarming rate. Now, a new report has painted the most detailed picture yet of where and why fresh water is disappearing — and outlined precisely how countries can address the problem.

Continental drying is a long-term decline in fresh water availability across large land masses. It is caused by accelerated snow and ice melt, permafrost thaw, water evaporation and groundwater extraction. (The report's definition excludes meltwater from Greenland and Antarctica, the authors noted.)

"We always think that the water issue is a local issue," lead author Fan Zhang, global lead for Water, Economy and Climate Change at the World Bank, told Live Science in a joint interview with co-author Jay Famiglietti, a satellite hydrologist and professor of sustainability at Arizona State University. "But what we show in the report is that ... local water problems could quickly ripple through national borders and become an international challenge."

Continents have now surpassed ice sheets as the biggest contributor to global sea level rise, because regardless of its origin, the lost fresh water eventually ends up in the ocean. The new report found this contribution is roughly 11.4 trillion cubic feet (324 billion cubic meters) of water each year — enough to meet the annual water needs of 280 million people.

"Every second you lose four Olympic-size swimming pools," Zhang said.

Far-reaching impacts

The report was published Nov. 4 by the World Bank. Its results are based on 22 years of data from NASA's GRACE mission, which measures small changes in Earth's gravity resulting from shifting water. The authors also compiled two decades' worth of economic and land use data, which they fed into a hydrological model and a crop-growth model.

The average amount of fresh water lost from continents each year is equivalent to 3% of the world's annual net "income" from precipitation, the report found. This loss jumps to 10% in arid and semi-arid regions, meaning that continental drying hits dry areas such as South Asia the hardest, Zhang said.

This is a growing problem. In a study published earlier this year, Zhang, Famiglietti and their colleagues showed that separate dry areas are rapidly merging into "mega-drying" regions.

"The impact is already being felt," Zhang said. Regions where agriculture is the biggest economic sector and employs the most people, such as sub-Saharan Africa and South Asia, are especially vulnerable. "In sub-Saharan Africa, dry shocks reduce the number of jobs by 600,000 to 900,000 a year. If you look at who are the people being affected, those most hard hit are the most vulnerable groups, like landless farmers."

Countries that don't have a large agricultural sector are also indirectly affected, because most of them import food and goods from drying regions.

The consequences for ecosystems are dramatic, too. Continental drying increases the likelihood and severity of wildfires, and this is especially true in biodiversity hotspots, the report found. At least 17 of the 36 globally recognized biodiversity hotspots — including Madagascar and parts of Southeast Asia and Brazil — show a trend of declining freshwater availability and have a heightened risk of wildfires.

"The implications are so profound," Famiglietti told Live Science.

The biggest culprit

Currently, the biggest cause of continental drying is groundwater extraction. Groundwater is poorly protected and undermanaged in most parts of the world, meaning the past decades have been a pumping "free-for-all," Famiglietti said. And the warmer and drier the world gets due to climate change, the more groundwater will likely be extracted, because soil moisture and glacial water sources will start to dwindle.

However, better regulations and incentives could reduce groundwater overpumping. According to the report, agriculture is responsible for 98% of the global water footprint, so "if agriculture water use efficiency is improved to a certain benchmark, the total amount of the water that can be saved is huge," Zhang said.

Globally, if water use efficiency for 35 key crops, such as wheat and rice, improved to median levels, enough water would be saved to meet the annual needs of 118 million people, the researchers found. There are many ways to improve water use efficiency in agriculture; for example, countries could change where they grow certain crops to match freshwater availability in different regions, or adopt technologies like artificial intelligence to optimize the timing and amount of irrigation.

Countries can also set groundwater extraction limits, incentivize farmers through subsidies and raise the price of water for agriculture. Additionally, the report showed that countries with higher energy prices had slower drying rates because it costs more to pump groundwater, which boosts water use efficiency.

Overall, water management at the national scale works well, according to the report. Countries with good water management plans depleted their freshwater resources two to three times more slowly than countries with poor water management.

Virtual water trade

On the global scale, virtual water trade is one of the best solutions to conserve water if it is done right, Zhang said. Virtual water trade occurs when countries exchange fresh water in the form of agricultural products and other water-intensive goods.

Global water use increased by 25% between 2000 and 2019. One-third of that increase occurred in regions that were already drying out — including Central America, northern China, Eastern Europe and the U.S. Southwest — and a big share of the water was used to irrigate water-intensive crops with inefficient methods, according to the report.

There has also been a global shift toward more water-intensive crops, including wheat, rice, cotton, maize and sugar-cane. Out of 101 drying countries, 37 have increased cultivation of these crops.

Virtual water trade can save huge amounts of water by relocating some of these crops to countries that aren't drying out. For example, between 1996 and 2005, Jordan saved 250 billion cubic feet (7 billion cubic meters) of water by importing wheat from the U.S. and maize from Argentina, among other products.

Globally, from 2000 to 2019 virtual water trade saved 16.8 trillion cubic feet (475 billion cubic meters) of water each year, or about 9% of the water used to grow the world's 35 most important crops.

"When water-scarce countries import water-intensive products, they are actually importing water, and that helps them to preserve their own water supply," Zhang said.

However, virtual water trade isn't always so straightforward. It might benefit one water-scarce country but severely deplete the resources of another country. One example is the production of alfalfa, a water-intensive legume used in livestock feed, in dry regions of the U.S. for export to Saudi Arabia, Famiglietti said. Saudi Arabia benefits from this exchange because the country isn't using its water to grow alfalfa, but aquifers in Arizona are being sucked dry, he said.

Reasons for optimism

The solutions identified in the report fall into three broad categories: manage water demand, expand water supply through recycling and desalination, and ensure fair and effective water allocation.

If we can make those changes, sustainable fresh water use is "definitely possible," Zhang said. "We do have reason to be optimistic."

Famiglietti agreed that small changes could go a long way.

"It's complicated, because the population is growing and we're going to need to grow more food," he said. "I don't know that we're going to 'tech' our way out of it, but when we start thinking on decadal time scales, changes in policy, changes in financial innovations, changes in technology — I think there is some reason for optimism. And in those decades we can keep thinking about how to improve our lot."

Some of the views expressed in this article are not included in the World Bank report. They should not be interpreted as having been endorsed by the World Bank or by its representatives.

A stalagmite deep inside a cave in Mexico's Yucatán Peninsula suggests that multiple droughts, including one lasting 13 years, may have contributed to the decline of the Maya civilization in the area.

By studying the mineral formation, the researchers could paint a detailed picture of rainfall by season, which enabled scientists to closely compare climate records with archaeological evidence of instability, according to a study published Wednesday (Aug. 13) in the journal Science Advances.

While the cause — or causes — of the Maya decline in the Yucatán Peninsula are still uncertain, many scientists think droughts played a major role. Previous studies suggested that years-long droughts occurred in southern Mexico during the ninth and 10th centuries, in what's known as the Terminal Classic period. Maya populations in the region declined during that time, while others thrived farther north, where the climate was drier, the study reported.

"This period in Maya history has been a cause of fascination for centuries," study co-author Daniel H. James, who conducted the research while he was a doctoral student in the Department of Earth Sciences at the University of Cambridge, said in a statement. "There have been multiple theories as to what caused the collapse, such as changing trade routes, war or severe drought, based on the archaeological evidence the Maya left behind. But in the past few decades, we've started to learn quite a lot about what happened to the Maya and why, by combining the archaeological data with quantifiable climate evidence."

To better understand rainfall patterns during the Terminal Classic, James and his colleagues studied the annual growth layers of a stalagmite from a cave near Tecoh, a municipality in the Yucatán. Like tree rings, these layers record information about how much water the stalagmite received from water dripping from the cave's ceiling in a given year. Variations in the chemical composition of each layer gave the scientists information about rainfall in each year's wet season, which runs from May to October.

"Knowing the annual average rainfall doesn't tell you as much as knowing what each individual wet season was like," said James, who is now an archaeologist at University College London. "Being able to isolate the wet season allows us to accurately track the duration of wet season drought, which is what determines if crops succeed or fail."

Related: Why did the Maya civilization collapse?

The team found evidence that there were eight wet-season droughts lasting longer than three years between A.D. 871 and 1021, some separated by just one wet year. These extended dry periods would have threatened Maya agriculture and possibly caused famines, the researchers said.

Though Maya in the region carefully managed their water in reservoirs and cisterns, the droughts were likely severe enough to destabilize the regional capital of Uxmal, the researchers wrote in the study. The Maya stopped building monuments and inscribing dates on them during these periods of drought, and the site's political system collapsed a few years after the most severe drought.

But other sites, like the nearby Chichén Itzá, were able to weather the droughts. While date inscription on monuments still stopped during the droughts, the site recovered, possibly because they relied on their extensive trade network for crops from central Mexico, the researchers noted.

The findings help shape a clearer picture of Maya decline in the Yucatán during the Terminal Classic period and will enable scientists to compare more detailed climate records with archaeological evidence of societal change.

"It hasn't been possible to directly compare the history of individual Maya sites with what we previously knew about the climate record," James said in the statement. "Stalagmites allow us to access the fine-grained detail that we've been missing."

Ancient Maya quiz: What do you know about the civilization that built pyramids across Mesoamerica?

Have you ever stopped by the grocery store on your way to a dinner party to grab a bottle of wine? Did you grab the first one you saw, or did you pause to think about the available choices and deliberate over where you wanted your gift to be from?

The people who lived in western Iran around 11,000 years ago had the same idea — but in practice it looked a little different. In our latest research, my colleagues and I studied the remains of ancient feasts at Asiab in the Zagros Mountains where people gathered in communal celebration.

The feasters left behind the skulls of 19 wild boars, which they packed neatly together and sealed inside a pit within a round building. Butchery marks on the boar skulls show the animals were used for feasting, but until now we did not know where the animals came from.

By examining the microscopic growth patterns and chemical signatures inside the tooth enamel of five of these boars, we found at least some of them had been brought to the site from a substantial distance away, transported over difficult mountainous terrain. Bringing these boars to the feast — when other boars were available locally — would have taken an enormous amount of effort.

A big feast from before the dawn of agriculture

Feasting activities are widely documented in the archaeological record, primarily from communities that rely on agriculture to generate a food surplus. In fact, it has been suggested feasting may have been a driving force behind the adoption of agriculture, although this theory has been widely debated.

While evidence from after the adoption of agriculture is plentiful from all reaches of the globe, evidence pre-dating agriculture is more sparse.

What is special about the feast at Asiab is not only its early date and that it brought together people from wider reaches of the region. It is the fact that people who participated in this feast invested substantial amounts of effort, so that their contributions involved an element of geographic symbolism.

Related: 'Cone-headed' skull from Iran was bashed in 6,200 years ago, but no one knows why

Food and culture

Food and long-standing culinary traditions form an integral component of cultures all over the globe. It is for this reason that holidays, festivals, and other socially meaningful events commonly involve food.

We cannot imagine Christmas without the Christmas meal, for example, or Eid without the food gifts, or Passover without matzo ball soup.

What's more, food makes for gifts that are highly appreciated. The more a food item is reminiscent of a specific country or location, the better. It is for this reason that cheese from France, crocodile jerky from Australia, and black chicken from Korea make for good currency in the world of gift giving.

Just like today, people who lived in the past noticed the importance of reciprocity and place, and formulated customs to celebrate them publicly.

At ancient feasts at Stonehenge, for example, research has shown people ate pigs brought from wide reaches of Britain. Our new findings provide the first glimpse of similar behaviour in a pre-agricultural context.

How to read a tooth

Did you know that teeth grow like trees? Much like trees and their annual growth rings, teeth deposit visible layers of enamel and dentine during growth.

These growth layers track daily patterns of development and changes in the dietary intake of certain chemical elements. In our study, we sliced the teeth of wild boars from Asiab in a way that allowed us to count these daily growth layers under the microscope.

We then used this information to measure the composition of enamel secreted at approximately weekly intervals. The variability in the isotopic ratios we measured suggests at least some of the wild boars used in the feast at Asiab came from considerable distance: possibly from at least 70 km, or two or more days' travel.

The most likely explanation is that they were hunted in farther reaches of the region and transported to the site as contributions to the feast.

Reciprocity is at the heart of social interactions. Just like a thoughtfully chosen bottle of wine does today, those boars brought from far and wide may have served to commemorate a place, an event and social bonds through gift-giving.

This edited article is republished from The Conversation under a Creative Commons license. Read the original article.

Ancient DNA from Stone Age burials in Turkey has finally put to rest a decades-long debate about whether the 9,000-year-old proto-city of Çatalhöyük was a matriarchal society. The research finally confirms what experts have long suspected: Women and girls were key figures in this agricultural society.

"With Çatalhöyük, we now have the oldest genetically-inferred social organisation pattern in food-producing societies," study co-author Mehmet Somel, an evolutionary geneticist at Middle East Technical University in Turkey, told Live Science in an email. "Which turns out to be female-centered."

The new research was published Thursday (June 26) in the journal Science.

Located in south-central Turkey, Çatalhöyük was built around 7100 B.C. and was occupied for nearly 1,000 years. The vast settlement — spread over 32.5 acres (13.2 hectares) — is known for its houses that were entered from the roofs, burials beneath the house floors, and elaborate symbolism that included vivid murals and a diverse array of female figurines.

When archaeologist James Mellaart first excavated Çatalhöyük in the early 1960s, he interpreted the numerous female figurines as evidence of a matriarchal society that practiced "mother goddess" worship, perhaps as a way of ensuring a good harvest following a major economic transition from foraging to cereal-based agriculture.

In the 1990s, Stanford archaeologist Ian Hodder took over excavations at Çatalhöyük, and his research suggested instead that the society was largely egalitarian, without meaningful social or economic differences between men and women.

Related: Rare, neolithic 'goddess' figurine discovered in Turkey

To further investigate the social organization at Çatalhöyük, in a new study, a team of researchers that included both Somel and Hodder analyzed the DNA of 131 skeletons dated to between 7100 and 5800 B.C. that were buried beneath house floors.

The researchers connected 109 people across 31 buildings and found that all first-degree relatives (parents, children and siblings) were buried together in the same building, while second-degree (uncles, aunts, nephews, nieces and grandparents) and third-degree relatives (such as first cousins and great grandparents) were often buried in nearby buildings. This suggests that nuclear or extended families had a role in structuring Çatalhöyük households, the researchers wrote in the study.

Matriarchy or just female lineages?

But there was another interesting trend in the intergenerational connections among house burials, the researchers noted: They were based primarily on maternal lineages.

"We weren't particularly looking for these maternal connections within buildings," Somel said, but "it clearly shows that male-centered practices people have often documented in Neolithic and Bronze Age Europe were not universal."

Ancient DNA analysis also revealed the biological sex of infants and young children, which is not possible to do based on skeletons alone until after puberty. Once these children's biological sex was determined, the researchers identified a female-linked trend in grave goods.

"The pattern of more burial gifts for female babies was also not something we were expecting," Somel said.

Çatalhöyük is the oldest society where DNA evidence has revealed a female-centered social organization.

"To my knowledge, this constitutes the first systematic evidence of such a continuously matrilineally organised Neolithic community," Jens Notroff, an archaeologist at the German Archaeological Institute who was not involved in the research, told Live Science in an email.

"We preferred using 'female-centered' instead of matrilineal because the latter is about how people define kin," Somel said. "Çatalhöyük households could have been matrilineal, but we think using more general terms might be preferable. It is always good to be cautious," he said.

But Benjamin Arbuckle, an archaeologist at the University of North Carolina at Chapel Hill who was not involved in the study, wrote in a perspective in Science that "if the sex patterns were reversed, there would likely be little hesitation in concluding that patriarchal power structures were at play."

"This is reflective of the difficulty that many scholars have in imagining a world characterized by substantial female power despite abundant archaeological, historic, and ethnographic evidence that matriarchal fields of power were and are widespread," Arbuckle said.

Çatalhöyük now stands in stark contrast to the patrilineal patterns seen in Neolithic Europe, Notroff said, which "raises the intriguing question of when, how, and why such a profound shift in social organisation occurred."

Analyzing skeletons from Çatalhöyük to understand social relationships is just the beginning, Somel said. Figuring out whether or not this site is unique is an important next step.

"We are now producing similar data from earlier societies from the region," he said, "so hopefully we'll have an answer soon!"

Stone Age quiz: What do you know about the Paleolithic, Mesolithic and Neolithic?

Women headed communities in eastern China about 4,500 years ago, a DNA analysis reveals.

While analyzing the ancient DNA of skeletons buried in Stone Age cemeteries in China, archaeologists discovered that the society was organized in an extremely rare way: Everyone belonged to one of two clans headed by women, and people were buried in their maternal clans for at least 10 generations.

At the archaeological site of Fujia in eastern China, researchers discovered two cemeteries roughly 330 feet (100 meters) apart flanking an ancient residential area. More than 500 burials were excavated and radiocarbon-dated to between 2750 and 2500 B.C.

In a study published June 4 in the journal Nature, an international team of researchers detailed their analysis of the DNA of 60 skeletons discovered at Fujia — 14 from the north cemetery and 46 from the south cemetery.

All 14 people from the north cemetery shared the same type of mitochondrial DNA (mtDNA), which is transmitted only from mother to child. This suggests that all of the people had the same maternal lineage, the researchers wrote in the study.

In the south cemetery, the researchers identified a different mitochondrial DNA lineage that was shared by 44 of the 46 people they tested. And when the researchers analyzed the Y chromosomes from the male skeletons, they found a high degree of diversity. Together, those findings suggest that the fathers of those buried in the cemeteries came from different lineages while the mothers were related.

"By integrating mtDNA and Y-chromosome analyses, we provide evidence that most individuals at Fujia, irrespective of their sex, were buried according to their maternal lineage," the researchers wrote in the study. In particular, both teenage and adult males were buried exclusively in their maternal clans, which "aligns with the common norms of a matrilineal society," according to the study.

Such findings of ancient societies organized along maternal lines are rare. Only three other studies have used DNA analysis to identify matrilineal communities: Chaco Canyon in New Mexico, Celtic elites in southern Germany, and the Durotriges in Iron Age Britain. Similar practices, however, have been found in contemporary Southeast Asian matrilineal societies.

Related: 'Overkill' injuries on Bronze Age skeletons reveal fierce feuding in ancient China

Deeper analysis revealed high rates of "consanguinity" — marrying a blood relative — over the span of 10 generations. While many people likely married their second or third cousins, four individuals showed signs of mating with first cousins or closer relatives.

While such consanguinity may not be the preferred marriage pattern, it inevitably occurs when you have small, closed-off societies, the researchers wrote.

This "unique social organization" has not been found previously in Stone Age East Asian populations, according to the researchers.

"It is exciting to find a matrilineal society in Neolithic China," Yu Dong, an archaeologist at Shandong University who was not involved in the study, said in a statement.

The Fujia study provides key insights into the social and environmental conditions during the transition from smaller to more complex societies, the researchers wrote. Future DNA and archaeological research should help clarify matrilineal social organization in early human societies, they added.

Terracotta Army quiz: What do you know about the 'warriors' in the 2,200-year-old tomb of China's 1st emperor?

Stark new satellite data reveal that the Colorado River basin has lost huge amounts of groundwater over the last few decades, with some research suggesting that this groundwater could run out by the end of the century.

But is that really the case? And if so, what could be done to prevent that happening?

While groundwater is being depleted, it's unlikely the water will ever run out completely. However, continued drainage of the basin could make the water table fall so far it's basically inaccessible, experts told Live Science.

Massive watershed

The Colorado River snakes through seven U.S. states (Wyoming, Colorado, Utah, New Mexico, Nevada, Arizona and California) and two Mexican states (Baja California and Sonora). Some 40 million people, including those in Phoenix and Las Vegas, depend on it for their water needs. But as supplies of this surface water have dried up over the past two decades — reaching record lows — more and more people have been pumping groundwater from far below the surface, mainly for agricultural use.

To get a better idea of how much groundwater is being extracted, Jay Famiglietti, director of science for the Arizona Water Innovation Initiative at Arizona State University, and his colleagues turned to data from NASA's Gravity Recovery and Climate Experiment (GRACE) and GRACE Follow-On satellite missions. These satellites track changes in Earth's gravity field to measure shifts in the amount of water above and below the ground, and when combined with data on snowpack, surface water and soil moisture, this information can allow scientists to estimate how much groundwater has been depleted.

The researchers estimate that since 2003, pumping from wells has drained about 28 million acre feet (34 cubic kilometers) of groundwater from the Colorado River Basin. This is akin to the capacity of Lake Mead, the largest U.S. reservoir, which sits behind the Hoover Dam on the Colorado River. The study was published May 27 in the journal Geophysical Research Letters.

About three-quarters of the groundwater depletion is happening in the river's lower basin, largely in Arizona, where water is pumped from desert aquifers to irrigate farmland, according to the study. In these largely rural areas, farms aren't usually hooked up to municipal water systems, and instead rely on water pumped from wells on the property. Because the wells are private, there is often no municipal, county- or state-level measurement of how much water they are drawing up.

Famiglietti and his colleagues estimate that annual groundwater losses in the basin averaged more than 1.2 million acre-feet (1.5 cubic kilometers) and if the trend continues, it could lead to water shortages and limit food production.

"We're passing a critical point where it is getting more and more expensive to go deeper into the aquifer, and the water quality is dropping," Famiglietti said.

Dozens of wells have dried up in the area. Collapsing aquifers have caused land subsidence, and created fissures.

Bottom of form

Ryan Mitchell, chief hydrologist at the Arizona Department of Water Resources, who was not involved in the new study, told Live Science that he welcomes the paper's findings and is concerned about the levels of estimated groundwater depletion in some areas. However, he takes issue with a sentence in the paper that suggests that an Arizona Department of Water Resources simulation indicated "complete depletion by the end of the century." He said the simulations don't indicate complete depletion of groundwater at all, let alone by the end of the century.

The groundwater won't run out, he said, but neither GRACE satellite data nor measurements of water use will tell us exactly how much water is left in aquifers.

"It's almost like it's an unknowable number in the same way that if someone said how many grains of sand are on the beach, you could make some assumptions and make some guesses but you can never actually know the exact amount of sand grains," Mitchell said.

Bridget Scanlon, a research professor in the Bureau of Economic Geology at the University of Texas at Austin, and her team recently used GRACE data to assess the implications of drought in the Colorado River basin. They saw similar patterns, finding that there was a period of high groundwater use as irrigation expanded between the 1940s and 1970s. Then, the amount of groundwater recovered during a wet period in the early 1980s and 1990s.

Related: Atlantic ocean currents are weakening — and it could make the climate in some regions unrecognizable

But since then, the picture has differed depending on how areas are managed. In "active management areas," or areas where water use is monitored, the levels of groundwater have stayed roughly level. In these areas, groundwater is pumped, but based on how much is drawn up, management agencies can divert more water to the depleted area to filter back down to the aquifer.

In unmanaged areas, no agency tracks how much groundwater is pumped, so agencies don't know when to replenish the aquifers. High extraction in unmanaged areas is driving the overall draining of groundwater, Mitchell told Live Science.

"We can't manage what we don't measure," he said. "It shows that if you have rules in place and you keep a close eye on water use and you actively manage it, you can kind of keep it at a sustainable level."

One thing is for sure: Waiting for precipitation to end the drought and replenish aquifers won't be enough. Studies imply that the flow of the Colorado River is expected to continue to decline thanks to climate-linked reductions in snowfall and rainfall — and that means there will be less surface water to use, less water to recharge aquifers and more reason to extract water from underground.

Drilling deeper wells is one solution, but there are problems with that, Famiglietti said. At some point, it will cost millions of dollars for a deep-enough well that will have high energy costs to pump water, he said, and that water is likely to require treatment.

"As you go deeper into the groundwater, that water has been sitting around in contact with soil and rocks for a long time, so it's dissolving solids and salts," Famiglietti said. This can lead to water that is salty, poor-tasting or that contains high levels of arsenic. "And because these are often refilled by agricultural water, they [are] collecting higher concentrations of pesticides and fertilizer," Famiglietti said.

Another option is to reduce water use, by, for example, changing what is farmed, to shift from water-intensive crops like alfalfa, Famiglietti said. "It can't be business as usual," he said. "We have to think about what our priorities are for water use."

"I'm as concerned about tomorrow as I am about 100 years from now," he said. “It's very clear that we need more groundwater management in the lower basin, which is mostly in Arizona. Only 18% by area is managed, and there's an awful lot of depletion happening outside of those areas."

Every expert Live Science talked with suggested that extending the area covered by active water management areas would help — first, by keeping tabs on what is being used where, and then trying to replace what is used.

As part of such schemes, water could be brought in from elsewhere, Scanlon said. For example, this already happens when San Antonio buys water and pipes it from East Texas more than 150 miles (240 kilometers) away.

"Groundwater is a finite resource," Mitchell said. "You need to be able to let it recharge naturally or be able to replenish what you use. He said Scanlon's research shows that "we're doing OK in the active management areas, and we're not doing so hot in the areas where we don't have some kind of framework in place."

A legislative bill to extend the areas that are actively managed has been proposed in Arizona, but similar ones have stalled after facing opposition. Those opposed say restricting water doesn’t protect existing agricultural use of groundwater and will stifle economic growth. Some also object to water use being decided at the state level when they would prefer smaller water districts with locally elected directors.

"We're not trying to spy on anyone; we just want to know what the water uses are," Mitchell said. "But it's hard because trust in governments is at an all-time low. We are trying to put things in place to help the mom-and-pop domestic wells — those folks who can't afford to drill 2,000-foot [600 meters] wells because it's just too deep and too expensive. We want to try to help them protect their water resources."

Editor's note: This article was updated at 9.00 a.m. ET on June 16 to correct a quote that was attributed to Bridget Scanlon instead of Ryan Mitchell.

Around 1,200 years ago in what is now Iraq, enslaved people who were forced to build a vast canal system defied authority and rebelled, a new study indicates.

Between A.D. 869 to 883 a group known as the Zanj, many of whom were enslaved people taken from Africa, rebelled against the Abbasid Caliphate (ruled from 750 to 1258) and disrupted its control over the region, according to historical texts. The records also suggest that during the Middle Ages, the Zanj helped build a large system of canals spanning nearly 310 square miles (800 square kilometers) that was used to irrigate agriculture near the city of Basra.

These canals are no longer used, but their earthen remains, including 7,000 human-made ridges, are still visible across the landscape. While researchers have long known about the canal system, no one had ever dated the ridges to see if they were constructed during the ninth-century Zanj rebellion.

To investigate, the researchers collected and dated soil samples from within four of the ridges in an effort to learn more about who built them. Using optically stimulated luminescence (OSL) dating, a technique that estimates when soil was last exposed to sunlight, the team determined that the ridges were built sometime between the late ninth to mid-thirteenth centuries A.D., they reported in their study published June 2 in the journal Antiquity.

"The close dating between some of the ridges and the time of the rebellion makes it very likely that people who were involved in the rebellion were involved in the creation of some of these features," study first author Peter J. Brown, an archaeologist at the Radboud Institute for Culture and History in the Netherlands and Durham University in the U.K., told Live Science in an email.

The results also indicate that construction of the ridges continued long after the rebellion ended. "We have a more limited understanding of exactly what happened afterwards and whether large numbers of slaves continued to work across this field system or whether 'free' local peasant farmers took over," Brown said.

The fact that the work on the ridges came to an end during the mid-thirteenth century could be related to the Mongol invasion of the region, which resulted in the sack of Baghdad in 1258, the authors wrote in their paper.

Enslaved life

The ninth-century revolt was not the Zanj's first rebellion. They also revolted in 689 to 690 and 694 to 695, according to historical texts. However, both of these insurrections were quickly suppressed. In contrast, the third revolt ended up "sparking more than a decade of unrest until the Abbasid state regained control of the region," according to the study.

Life as an enslaved person digging canals was brutal, and medieval texts provide some clues as to what life was like for the Zanj.

Before the rebellion, the textual sources describe work camps distributed throughout the canal region, with groups of 50 to 500 enslaved people in each camp, Brown said.

"They seem to have been in a servile situation with 'agents' or 'masters' who were in charge of them, and the historical sources suggest they were treated poorly but we don't have details about the conditions in which they lived," Brown said.

The labor they had to perform was backbreaking.

"The workers who built this system would have had to dig out the canals and pile up earth into the large ridge features we can see on the ground today, " Brown said, noting that the slaves may have used animals such as donkeys to help with transporting sediment.

After the canals were built, they needed to be cleaned frequently "to keep them functional as water carries silt that would be deposited within the canal beds," Brown said. "Over time, [the silt] would lead to them becoming unusable if they were not routinely cleaned."

Adam Ali, an assistant professor of Arabic language at the University of Toronto who has a doctorate in Islamic history, said that the study is interesting but cautioned that the samples come from just four of the ridges and more work is needed to verify the study findings.

"I think that this study opens an avenue for further the discussion and examination of these ridges and what they can tell us," Ali, who was not involved in the research, told Live Science in an email.

The possibility that slaves from Africa kept being used on the canals after the rebellion is important, Kristina Richardson, a professor of Middle Eastern and South Asian languages and cultures and history at the University of Virginia, told Live Science in an email. "The findings are extraordinary and surprising, because they upend the historical consensus that Middle Easterners stopped using East Africans as agricultural slaves after the suppression of the Zanj Rebellion in 883."

The Stone Age was a prehistoric period that lasted more than 3 million years, from the point when human ancestors began using stone tools until the time we invented metalworking.

Archaeologists often break up this lengthy time span into three periods — the Paleolithic (3.3 million to 12,000 years ago), the Mesolithic (12,000 to 10,000 years ago), and the Neolithic (10,000 to 4,000 years ago) — although there is regional variation in dates.

While the Paleolithic period involved a nomadic lifestyle and the invention of stone tools, the Neolithic period was ushered in with the development of agriculture and settled communities.

Are you up to date on recent research on the Stone Age? Don't take your knowledge for granite — try your best to rock our gneiss little quiz.

Remember to log in to put your name on the leaderboard; hints are available if you click the yellow button. May the quartz be with you!

More science quizzes

—Stonehenge quiz: What do you know about the ancient monument?

—Neanderthal quiz: How much do you know about our closest relatives?

—Viking quiz: How much do you know about these seaborne raiders, traders and explorers?

A pest called the fall armyworm has spread across the globe, threatening food security in more than 80 countries. But now, new research has revealed Australian fungi that eat the worms from the inside out — and may be the key to stopping the pests' destructive spread.

Fall armyworms (Spodoptera frugiperda) are a type of grey moth native to tropical areas of Central and South America, and in recent years, they have become one of the world's most devastating corn crop pests. The adult moths can migrate long distances aided by global trade and by winds, and they are now present in Europe, Asia, Africa and Australia.

The longest recorded armyworm flight was from Mississippi to southern Canada, covering 870 miles (1,400 kilometers) in just 30 hours, Johnnie van den Berg, a zoologist at North-West University in South Africa who was not involved with the new research, told Live Science in an email.

One fertile S. frugiperda female can lay 1,000 to 2,000 eggs in her lifetime. And the offspring develop rapidly: After eggs are laid on corn plants, the larvae are big enough to cause serious leaf damage in about a week, van den Berg said. The worm-like larvae are also difficult to detect, as they are small and hard to spot — often, farmers might not detect fall armyworms until crop damage has already begun.

Related: What's the difference between a moth and a butterfly?

These pests mostly eat corn but can feed on a huge variety of other crops, damaging wheat, cotton, sugarcane and vegetables.

Farmers have tried to control the spread of armyworms with pesticides, but the pests can quickly develop a resistance to chemical pesticides. So scientists and farmers have explored alternatives for managing the armyworm problem, such as introducing viruses that attack the worms, applying botanical extracts and engineering crops to be resistant. But these methods vary both in their viability on a large scale and in their cost effectiveness.

Now, new research from Australia's Department of Primary Industries (DPI) announces a promising breakthrough: Fungi native to Australia that attack the fall armyworm.

The researchers have identified five types of fungi that can kill fall armyworms within 24 hours of exposure. For example, the fungus Nomuraea rileyi attaches to the armyworm's skin, covering it, before spreading inside the larva's body. It then eats the armyworm from the inside out.

The researchers shared their findings in a meeting on fall armyworm management held in March, and with Australian journalists. They have not yet been published in a peer-reviewed journal.

In separate research, another team of scientists discovered additional types of fungi that are able to kill fall armyworms, along with some types of bacteria. Some strains of the fungus Beauveria bassiana killed about 75% of armyworms within 48 hours. The bacterium Bacillus thuringiensis (Bt) was also found to be effective in killing fall armyworms.

This research team still doesn't fully understand how the B. bassiana fungus kills armyworms, study co-author Wee Tek Tay, a biologist at the Commonwealth Scientific and Industrial Research Organisation (CSIRO) in Australia, told Live Science in an email. It's better understood how the bacterium Bt works: it creates holes in cells of the armyworms' gut, which ultimately starves them, triggers blood poisoning, or both.

The CSIRO researchers say their work is still in the early stages, and more research is needed to move toward application for pest management.

"The use of biological control agents … can be very effective," Tay noted. However, deploying the fungi would "require careful resistance management planning," he said, because just like conventional insecticides, misusing fungi could lead to resistance.

The fungi his team tested are commonly found in the natural environment and regularly encountered by insects, he added, so they don't anticipate the fungi having bad ecological impacts if they were used to control fall armyworms.

The DPI scientists, meanwhile, are now working to get N. rileyi approved for sale as a pest control measure, so it can be made available to farmers.

Before the fungi can enter large-scale use, the potential risk and unintended consequences the fungi might have on the environment must be assessed, van den Berg said. But compared to the impact of chemical insecticides, the impact of bacteria and fungi tend to be much less harmful to the environment, he said.

Editor's note: This story was updated on April 11, 2025, to provide information about Bacillus thuringiensis and to clarify how it affects armyworms.

India's Thar Desert has become 38% greener over the past 20 years, driven by a combination of climate change and agricultural expansion, according to a new study.

The past two decades have seen more people living in this desert and changing the landscape, making it more agricultural and urban, which is part of the reason why the desert has become greener, researchers said. The other piece of the puzzle is climate change, which has caused increasing monsoon precipitation in the region.

The Thar Desert, also called the Great Indian Desert, spans 77,000 square miles (200,000 square kilometers) in northwestern India and southeastern Pakistan. Although many deserts throughout the world are facing worsening droughts, the Thar Desert has become a hub of urban and agricultural growth, making it the most populated desert in the world with more than 16 million residents.

"Increased water and energy availability have led to expansion in agricultural and urban areas with a considerable increase in crop yields in the region," study co-author Vimal Mishra, a civil engineer at the Indian Institute of Technology Gandhinagar, told Live Science in an email. "There is no other desert in the world that has experienced increases in urbanization, agriculture, and precipitation during the recent period,"

The new study, published April 3 in the journal Cell Reports Sustainability, analyzed satellite data from 2001 to 2023. Mishra and his team found that the desert became, on average, 38% greener during this time, with more vegetation visible in satellite images.

Related: Why are deserts dry?

To understand why exactly greening is happening, the researchers also looked at historical records of population expansion in the Thar Desert, irrigation infrastructure, and climate models.

The findings show the Thar Desert's greening has been driven primarily by more rain during summer monsoon seasons — a 64% rise in precipitation overall — and secondly by irrigation infrastructure bringing groundwater to the surface outside of the monsoon season.

The authors suggest that sustainable management of water resources in the Thar Desert can help this area adapt and continue to sustain its growing population. However, warmer temperatures may threaten the 16 million people who live in this desert, and overuse of groundwater for irrigation can deplete resources, the researchers noted.

Sustainable water management practices, drought-resistant crops, adaptations to rising heat and renewable energy must all be part of future development in the Thar Desert, the researchers said.

The increased monsoon rainfall could also mean more flooding, as climate models project this increased rainfall will happen in bursts in extreme weather events, which can damage homes and buildings in the desert.

However, if managed and adapted to, the increased rain could also enable people and agriculture to flourish in the region. Researchers behind a separate study projected that even more of the landscape will become green by the end of the 21st century.

This change would boost food security in the region but could threaten the native biodiversity of desert-adapted specialist species and traditional methods of nomadic farming. The scientists warned that the need to preserve these aspects of the desert environment must be taken into consideration as development continues.

Name: Model of a Granary with Scribes

What it is: A wooden model with plaster, paint and linen decorations

Where it is from: Thebes, Egypt (modern-day Luxor)

When it was made: Circa 1980 B.C.

Related: Thule snow goggles: 1,000-year-old Arctic eyewear carved from walrus tusks

What it tells us about the past:

This decorated wooden diorama was discovered in a secret chamber of an ancient Egyptian tomb in Thebes (now Luxor) in 1920. The enormous tomb was that of Meketre, the chief steward of the pharaoh's household, who died around 1980 B.C., in Egypt's 12th dynasty during the Middle Kingdom, a period known for its distinctive art. The model represents a miniature granary, which suggests the importance of wheat and barley in ancient Egyptian society.

The model, which is on view at the Metropolitan Museum of Art in New York City, was made from a wooden box measuring 29.5 by 22 by 14.4 inches (74.9 by 56 by 36.5 centimeters). The slightly peaked corners evoke an ancient style of architecture that helped protect against thieves and rodents, according to the Met. Inside, the box is divided into two sections: the place where the grain was stored and the place where measuring and accounting took place.

Models of 15 men, each roughly 7.9 inches (20 cm) tall, were also included in the diorama. Six are carrying sacks of grain, while the other nine are recording the supply on papyrus scrolls and wooden tablets.

Egypt's agricultural wealth came primarily from cereals, including wheat and barley, and the pharaohs controlled the main food-producing area: the Nile Valley. Keeping track of grain supplies was therefore crucial to ancient Egyptian society, according to the Met. In Meketre's role as chief steward, he was likely in charge of all royal estates that supplied the palace with grain and other food.

The secret chamber of Meketre's tomb revealed 24 models in total, including a garden of fig trees and a sporting boat. Half of these models are in the Met's collection, while the other half are in the Egyptian Museum in Cairo.

It is unclear why some ancient Egyptians were buried with these models, but some scholars suspect the dioramas may have been created to help support the dead in the afterlife.

A volcanic eruption in 2910 B.C. may be the reason Neolithic people on a small island in the Baltic Sea buried hundreds of stones decorated with plant and sun imagery, archaeologists suggest in a new study.

"We have known for a long time that the sun was the focal point for the early agricultural cultures we know of in Northern Europe," Rune Iversen, an archaeologist at the University of Copenhagen, said in a statement. These stones "were probably sacrificed to ensure sun and growth."

In a study published Thursday (Jan. 16) in the journal Antiquity, Iversen and colleagues detailed the discovery of 614 stone plaques and plaque fragments on the Danish island of Bornholm, located south of Sweden in the Baltic Sea. The objects were found scattered throughout a palisade ditch. Based on the pottery style and the radiocarbon dates from charcoal found nearby, the researchers concluded that the decorated stones were deliberately placed there around 2900 B.C.

The vast majority of the stone plaques were made from black shale — a dark, flaky sedimentary rock found on the island — while others were made from quartz and flint. Most of the plaques were also decorated with incised designs, including sun and plant motifs.

Although a handful of these "sun stones" have been found on Bornholm previously, the large number of them found in one place spurred the researchers to seek a potential reason for the unique deposit.

Related: Ritually bent Bronze Age sword unearthed in Danish bog is 'very rare find'

Neolithic people appear to have buried the stones at a critical juncture, as the researchers discovered that the area was transformed into a more solid, fortified site just after the stones were deposited. Perhaps a natural disaster or climatic event that caused crops to fail triggered the stone "sacrifice," the researchers suggested in their study.

Based on extensive evidence of prehistoric climate events, the researchers made a connection between the burial of the stones and a volcanic eruption in 2910 B.C. that almost certainly negatively affected weather and harvests across the Northern Hemisphere.

"These depositions could have been made during a time of stress with the purpose of bringing back the sun and re-establishing agricultural production," the researchers wrote in their study. "They could also have been made when the climate crisis was over, as an act of celebration for the return of the sun."

After the stone deposit, a new kind of culture began on Bornholm, the researchers explained in the study. People stopped building massive tombs, began creating more fortified settlements, and formed new social networks with people in Scandinavia. But the importance of the sun may not have diminished, as Neolithic societies across Europe relied on the sun for their harvest.

"It is quite simply an incredible discovery, which demonstrates that depositions honouring the sun is an ancient phenomenon, which we encounter again in South Scandinavia during the climate disaster caused by a volcanic eruption in the year 536 AD," study co-author Lasse Vilien Sørensen, an archaeologist at the National Museum of Denmark, said in the statement.

Each year, Escherichia coli, or E. coli, causes about 265,000 infections and 100 deaths in the United States. Many of those infections result in foodborne illness. Notably, E. coli contamination has historically caused large and notable food recalls. In 2023 alone, the U.S. Food and Drug Administration (FDA) recalled 72,858 pounds (33,048 kilograms) of E. coli-contaminated food.

But how does E. coli get into food in the first place?

First off, it's important to understand that not all strains of E. coli are the same.

"E. coli are a group of common bacteria that are found naturally in many places including the environment, food, water and in the intestines of people and certain animals," Janell Goodwin, a spokesperson for the FDA, told Live Science in an email. "Most E. coli are harmless and contribute to intestinal health."

However, certain E. coli strains are dangerous because they produce Shiga toxins, harmful substances that can damage the digestive tract. These strains are called Shiga-toxin-producing E. coli (STEC). People can become sick if they eat or drink food or water contaminated by STEC, and children under 5 and adults over 65 typically face the greatest risk of severe infections.

How dangerous bacteria contaminate food

There are a number of ways STEC can end up in food. "Food goes through several steps from where it is grown or made to the dining table," a spokesperson for the U.S. Centers for Disease Control and Prevention (CDC) told Live Science in an email. "Contamination can occur at any point along the chain — during production, processing, distribution or preparation."

Goodwin noted that one major route of infection occurs through animals, including both livestock and wildlife. Animals may carry STEC in their intestines and then shed it through their feces. Even a tiny amount of feces present on a livestock carcass can lead to E. coli contamination in the resulting products made from that flesh. Ground beef is at particularly high risk of contamination, for instance, because cattle are the main carrier of E. coli O157, an especially dangerous strain of STEC. The bacteria can spread around when the meat is ground, and this has resulted in major recalls.

Bacteria from livestock or wildlife feces can also contaminate produce. For example, runoff from livestock farms can shepherd E. coli into water used to irrigate crops. Improperly treated manure used as fertilizer can also carry the harmful bacteria.

In addition, farmworkers who come into contact with livestock or produce may unknowingly transfer E. coli during planting, harvesting or processing if they don't carefully follow safety protocols aimed at preventing the transfer of bacteria from fecal contamination.

Harmful E. coli strains can also taint food on the other end of the food processing chain, such as at a restaurant. "Carriers [who shed the bacteria in their feces] can spread infections when food handlers do not use proper hand washing hygiene after using the restroom," Goodwin said.

Related: Bacteria from meat may cause a half-million UTIs a year

Stopping the spread

The FDA recommends that people wash their hands with warm water and soap for at least 20 seconds before and after handling any raw food. The agency also emphasizes the importance of handwashing before, during and after changing a baby's diaper, and when making contact with livestock.

Countertops and cutting boards can be another source of contamination, so the FDA advises washing those carefully as well.

Certain foods are more likely to be contaminated with harmful E. coli than others. A 2021 report from the CDC found that beef — particularly raw or undercooked ground beef — and vegetable row crops, such as leafy greens, were the source of 80% of O157 infections in the U.S. from 1998 to 2021. Raw and undercooked poultry; raw sprouts such as alfalfa; and products made with unpasteurized, or raw, milk are also common culprits, Goodwin added.

Researchers are still working to gain a better understanding of the factors that contribute to E. coli contamination in the food supply. One recent study found that seasonal changes in temperature may influence the likelihood of E. coli outbreaks tied to lettuce grown in California, while another study from Arizona found that STEC can spread through the air, traveling from large livestock facilities to nearby produce farms.

Goodwin also noted that, while it can be alarming to see more regular E. coli recalls and advisories in the news, it doesn't necessarily mean that the food safety system is failing.

"The occurrence of recalls and advisories means that manufacturers, importers, and distributors are monitoring for issues and taking action when they detect a problem," she said. "Consumers should know that recalls and outbreak advisories indicate that the problem has been identified and is being addressed. "

This article is for informational purposes only and is not meant to offer medical advice.

As millions of people across the U.S. recently looked up to the skies to witness widespread auroras dancing overhead, some farmers were left perplexed as their tractors seemingly started doing the same.

The malfunctioning vehicles, which have been unexpectedly swaying from side to side as they work the land, have been boogying to the beat of supercharged magnetic disturbances triggered by explosive solar storms, experts say. Simply put: Solar particles are tampering with the machines' GPS systems.

Solar activity has been way up this year thanks to solar maximum, the peak of the sun's roughly 11-year cycle, which scientists confirmed was officially well underway in October. As a result, solar flares have frequently erupted from the sun throughout 2024, and some of these explosions have also launched large clouds of plasma, known as coronal mass ejections (CMEs), at Earth. When these CMEs hit our planet, they can create massive disturbances in Earth's magnetic field, known as geomagnetic storms, potentially triggering radio blackouts and widespread aurora displays.

Between May 10 and May 12, Earth was hit by five consecutive CMEs, which triggered the most powerful geomagnetic storm in more than 21 years, and likely painted some of the most vibrant auroras over the last few centuries. This event was classed as an "extreme" G5 storm — the most powerful threshold these disturbances can reach.

During this supercharged storm, farmers across large parts of the U.S. reported some unusual activity with their tractors, which started "dancing" from side to side, Spaceweather.com recently reported.

Related: 32 stunning photos of auroras seen from space

"Our tractors acted like they were demon possessed," Elaine Ramstad, an amateur aurora chaser who was helping out on a family farm in northern Minnesota during May's geomagnetic storm, told Spaceweather.com. "All my cousins called me during the storm to tell me that 'my auroras' were driving them crazy while they were planting."

Most large, modern tractors use GPS to help their drivers plant and harvest crops in perfectly straight lines, maximizing farmers' potential output. But to do this, the tractors' computers need to be in clear and constant contact with GPS satellites, located in low Earth orbit (LEO). During geomagnetic storms, our planet's upper atmosphere can expand, get pulled out of shape and become more dense as it soaks up solar radiation, which can interfere with GPS signals being sent to and from LEO.

"If it just happens at the wrong time, in the wrong season, if it holds everything up by three or four days. It can have a significant impact on agriculture," Scott McIntosh, a solar physicist and vice president of the space weather prediction and mitigation company Lynker Space, told Live Science's sister site Space.com.

Tractors built by John Deere and using their GPS navigation system, commonly referred to as "Autosteer," seemed to have been particularly affected by the geomagnetic disturbances, with several farmers reporting issues with the vehicles during May's superstorm, Business Insider reported at the time. But other vehicles were also impacted.

"At least 50% of all farmers are very reliant on GPS and use it on every machine all year long," Ethan Smidt, a service manager for John Deere, told Spacewetaher.com.

But these issues have not just been confined to May's freak event. Many farmers in the U.S. also experienced the same issues during a "severe" G4 storm in early October.

"My GPS was off by close to a foot [in October]. Twice while on Autosteer, the tractor danced a row to the left, to the right… so I had to loop around and start over," Ramstad said. "By nightfall, there was no controlling the Autosteer."

This issue also impacted other farmers across many other northern states, such as Indiana. An unnamed farmer from Iowa also shared striking photos of wonky rows of crops planted during October's storm, showing how the tractor had continually danced back and forth along the lines.

Many other GPS-reliant technologies were also likely impacted by the recent geomagnetic storms, and some satellites have even been knocked out of LEO by the increased drag from our temporarily expanding atmosphere. However, it will take time to properly assess the impacts of these storms and solar maximum in general.

The sun's explosive peak could persist for up to a year, and some scientists are warning that solar activity will remain high, or potentially even increase, during a newly described phase of the sun's cycle, known as the "battle zone" — a period after solar maximum during which large magnetic bands on the sun fight one another. As a result, we will likely see many more GPS-related space weather effects in the near future.

The goal of the 2021 Global Methane Pledge is bold: cut methane emissions by 30% by the end of the decade. This is to buy us vital time to work on cutting carbon dioxide emissions. Over 150 nations have now signed up to the pledge — representing more than half of the world's emissions of an extremely potent but short-lived greenhouse gas.

To put the pledge into action, many leaders announced policies to cut methane. However, the latest research shows global methane emissions are still rising rapidly. Atmospheric concentrations are now growing faster than at any other time since global record-keeping began about 40 years ago.

These findings are published today in our fourth global methane budget, in a paper and pre-print research undertaken through the Global Carbon Project, with contributions from 66 research institutions around the world.

Natural sources of methane include decaying organic matter in wetlands. But humans have supercharged methane emissions. We tracked changes in all major sources and sinks of this potent greenhouse gas and found humans are now responsible for two-thirds or more of all global emissions.

This is a problem, but we can improve upon it. Cutting methane emissions is one of the best and only short-term levers we can pull to slow the rate of climate change.

Related: The 165-year reign of oil is coming to an end. But will we ever be able to live without it?

Why is methane so important?

After carbon dioxide, methane is the second most important greenhouse gas contributing to human-driven global warming.

Although human activities emit much less methane than carbon dioxide in real terms, methane has a hidden punch — it's 80 times as effective as CO₂ in trapping heat in the first two decades after it reaches the atmosphere.

Since the pre-industrial era, the world has heated up by 1.2°C (taken as an average of the past 10 years). Methane is responsible for about 0.5°C of warming, according to the latest reports by the Intergovernmental Panel on Climate Change (IPCC).

In the atmosphere, methane rapidly mixes with oxygen and converts into carbon dioxide and water. By contrast, carbon dioxide is a much more stable molecule and will stay in the atmosphere, trapping heat, for thousands of years until absorbed by ocean and plants.

The combination of short lifespan and extreme potency make methane an excellent candidate for efforts to rapidly tackle climate change.

Methane is not slowing

In the early-to-mid-2000s, methane emissions growth rates actually fell. Analyses suggest it was driven by a combination of reduced fossil fuels emissions and chemical changes in the atmosphere's capacity to destroy methane.

Since then, however, methane has surged. Methane emissions from human activities increased by 50-60 million tonnes per year over the two decades to 2018-2020 — a 15-20% increase.

This doesn't mean atmospheric methane goes up by the same amount, as methane is constantly being broken down.

During the 2000s, an extra 6.1 million tonnes of methane entered the atmosphere each year. By the 2010s, the rate of growth was 20.9 million tonnes. In 2020, growth hit 42 million tonnes. Since then, methane has been added even more rapidly. Growth rates are now higher than any previously observed year.

Where does the methane come from?

Human activities such as farming livestock, coal mining, extracting and handling natural gas, growing rice in paddies, and putting organic waste in landfills contribute about 65% of all methane emissions. Of this, agriculture (livestock and rice paddies) contributes 40%, fossil fuels 36%, and landfills and wastewater 17%.

Methane emissions from fossil fuels are now comparable to livestock emissions. The fastest growing contributors are from landfill and fossil fuels (think natural gas escaping during extraction and processing).

Our impact is even higher when we account for indirect emissions such as the leaching of organic matter into waterways and wetlands, the construction of reservoirs, and the impacts of human-driven climate change on wetlands.

In 2020, human activities led to emissions of between 370 and 384 million tonnes of methane.

The remaining emissions come from natural sources, primarily the decomposition of plant matter in wetlands, rivers, lakes, and water-saturated soils. Tropical wetlands are particularly large emitters. The world's large areas of permafrost (permanently frozen ground) also produce methane, but at relatively low rates. As permafrost melts due to higher temperatures, this is changing.

Regional contributions and trends

Who emits most? By volume, the top five nations in 2020 were China (16%), India (9%), the United States (7%), Brazil (6%) and Russia (5%). The fastest-growing areas are China, South Asia, Southeast Asia, and the Middle East.

European nations have begun to lower their emissions over the last two decades, due to efforts to cut emissions from landfill and waste, followed by smaller cuts in fossil fuels and farming. Australia may also be lowering emissions mainly from farming and waste.

What does this mean for net zero?

Unchecked methane emissions are bad news. Recent observed atmospheric concentrations of methane are consistent with climate scenarios with up to 3°C of warming by 2100.

To keep global temperatures well-below 2°C — the goal of the 2015 Paris Agreement — means cutting methane emissions as rapidly as possible. Methane has to be cut almost in half (45%) by 2050 to achieve that goal.

It's not an impossible problem. We now have have methods of rapidly cutting methane for every sector.

The oil and gas sector could cut their emissions 40% at no net cost, according to the International Energy Agency.

In agriculture, we can achieve rapid reductions by feed additives to reduce methane belched from cows, sheep, goats and buffalo, and by mid-season drainage in rice paddies.

Capturing landfill methane and using it for energy production or heat is now well established.

Three years ago, the world committed to slash methane emissions. Our findings show that we need to rapidly accelerate solutions across the globe to address and reduce methane emissions.

This edited article is republished from The Conversation under a Creative Commons license. Read the original article.

The murder of sacrificial victims by "incaprettamento" — tying their neck to their legs bent behind their back, so that they effectively strangled themselves — seems to have been a tradition across much of Neolithic Europe, with a new study identifying more than a dozen such murders over more than 2,000 years.

The study comes after a reassessment of an ancient tomb that was discovered more than 20 years ago at Saint-Paul-Trois-Châteaux near Avignon, in southern France. The tomb mimics a silo, or pit where grain was stored, and it held the remains of three women who were buried there about 5,500 years ago.

The new study, published Wednesday (April 10) in the journal Science Advances, reinterprets the positions of two of the skeletons and suggests the individuals were deliberately killed — first by tying them up in the manner called "incaprettamento" and then by burying them while they were still alive, perhaps for an agricultural ritual.

Study senior author Eric Crubézy, a biological anthropologist at Paul Sabatier University in Toulouse, France, told Live Science that there was a lot of agricultural symbolism to the tomb. He noted that a wooden structure built over it was aligned with the sun at the solstices and that several broken stones for grinding grain were found nearby. "You have the alignment, you have the silo, you have the broken stones — so it seems that it was a rite related to agriculture."

Related: Skull of Neolithic 'bog body' from Denmark was smashed by 8 heavy blows in violent murder

To investigate the idea of human sacrifice at Saint-Paul-Trois-Châteaux, Crubézy, who worked on the initial discovery of the tomb, and colleagues examined earlier archaeological studies of tomb sites throughout Europe. The team included forensic pathologist Bertrand Ludes, of Paris Cité University and the study's lead author.

They found evidence of 20 probable cases of sacrificial murders using incaprettamento at 14 Neolithic (New Stone Age) sites dating to between 5400 and 3500 B.C. They also found papers describing Mesolithic (Middle Stone Age) rock art in the Addaura Cave in Sicily, made between 14000 and 11000 B.C., that seems to depict two human figures bound in the incaprettamento manner.

Crubézy said it appears incaprettamento originated as a sacrificial custom in the Mesolithic period, before agriculture, and later came to be used for human sacrifices associated with agriculture in the Neolithic period.

As a method of human sacrifice, incaprettamento seems to have been widespread across much of Neolithic Europe, with evidence of the practice at sites ranging from the Czech Republic to Spain. The earliest is a tomb near Brno-Bohunice in the Czech Republic that is dated to about 5400 B.C., and the latest is the tomb at Saint-Paul-Trois-Châteaux, suggesting that the practice persisted for more than 2,000 years, Crubézy said.

Gruesome murders

The bindings used to tie the two individuals at Saint-Paul-Trois-Châteaux have long since decayed, but a few features of their skeletons — such as the unusual positions of their legs — suggest how they died, Crubézy said.

The third woman in the tomb seems to have been older and likely died from natural causes, the researchers found. She was also interred normally for the time, on her side in the center of the tomb. This suggests that she had been ceremonially buried after her natural death and that the two younger women had been sacrificed to be buried with her, he said.

The two sacrificial victims seem to have been pinned down with heavy fragments of stones used for grinding grain, indicating that, despite their bindings, they were still alive when they were buried, he said.

Today, the gruesome incaprettamento murder method is associated with the Italian Mafia, who have sometimes used it as a form of warning or reprimand.

Crubézy said it wasn't known why incaprettamento was used for Stone Age human sacrifices, but it might have been because a person bound in this way could be seen as strangling themselves, rather than being killed by someone else.

One thousand years ago, the first settlers of Rapa Nui — also known as Easter Island — feasted on a fusion cuisine of plants native to Polynesia but also ones indigenous to South America, around 2,300 miles (3,700 kilometers) away, a new study finds.

Researchers discovered the food remnants by identifying starch grains clinging to obsidian blades at the archaeological site of Anakena, the earliest known settlement on Rapa Nui, which was occupied from about A.D. 1000 to 1300, according to the study, published Wednesday (March 20) in the journal PLOS One. The finding suggests that the early Polynesians had regular contact with the people of South America as far back as a millennium ago.

The southeastern Pacific island Rapa Nui is known primarily for the hundreds of monolithic human statues called moai that were erected on stone ceremonial platforms called ahus. The island was formed from three volcanoes, two of which are now extinct, and early settlers carved the moai from the consolidated volcanic ash.

Although Rapa Nui was not known to the wider world until Dutch explorers landed there on Easter Sunday in 1722, the native people had already lived on the island for hundreds of years. But the specific timing of their settlement and their geographic origins remain somewhat mysterious, and experts disagree about whether the earliest settlers came from Polynesia, South America or both. The oral history of the Rapa Nui people suggests that at least one round-trip voyage to South America was made from the island during the early years of its settlement.

To investigate the early years of the Rapa Nui settlement, researchers took a deep dive into ancient food resources. Scientists already knew from animal bones that early settlers consumed fish, dolphins, seals, chickens and rats, but plant remains have not been as thoroughly investigated.

Related: Undeciphered script from Easter Island may predate European colonization

The researchers looked at 20 obsidian blades excavated from under the ahu at Anakena in 1987, which revealed evidence of 46 starch grains. Due to their size and preservation, though, only 21 grains could be classified, belonging to eight species: breadfruit, cassava (also known as yuca or manioc), taro, purple yam, sweet potato, Tahitian apple, achira and ginger. There were, in some cases, multiple species on a single obsidian blade, so the researchers suggested that the tools were multipurpose, used for cutting, scraping off peels, grating or other kinds of processing.

Starch grains from yam and taro were not a surprise, having been previously identified on Rapa Nui, but the team's discovery of breadfruit and Tahitian apple is new, as neither plant had been found on the island before, and their discovery of ginger is a first for Remote Oceania, the researchers wrote. Both breadfruit and Tahitian apple are essential Polynesian crops, probably brought on canoes by the earliest Polynesian settlers, while ginger may have been used as a medicine and spice.

In addition to the Polynesian crops, the researchers found three species of South American starchy foods: achira, sweet potato and cassava. In particular, "the identification of sweet potato starch grains in the lower levels of the Anakena site suggests an introduction of this species to Rapa Nui during the earliest settlement period," the researchers wrote. Cassava also seems to have been present on Rapa Nui long before European explorers visited its shores.

"Our results show that, by the time that people were living at the Anakena site, they already had voyaged to the South American coast and been in contact with South American peoples," Andrea Seelenfreund, an archaeologist at the Academy of Christian Humanism University in Chile and one of the study authors, told Live Science in an email.

"We argue that Polynesian (Pacific) voyagers reached the coast of the American continent and interacted with local American populations and, at some later point, returned to the Pacific islands with some American crops that were then cultivated on different islands alongside traditional Pacific crops," Seelenfreund said.

Jo Anne Van Tilburg, an archaeologist at UCLA and director of the Easter Island Statue Project, told Live Science in an email that this research "contributes new information to the ongoing discussion of Rapa Nui prehistory." Van Tilburg, who was not involved in the study, said that, while the results are interesting and thought-provoking, some skepticism about the researchers' inferences is warranted because their method of identifying the ancient starch grains had low accuracy in some cases. 

While the researchers caution in their study that more work needs to be done — such as looking for other plant species from the wider Pacific — they suggest it is highly likely there was sustained interaction between Polynesian and South American peoples nearly a millennium ago.

"We have to keep in mind that long distance ocean voyaging was a highly developed skill by Pacific Island people," Seelenfreund said.

Python meat is a low-effort and sustainable protein alternative that could soon slither onto our dinner plates, scientists suggest.

The researchers argue there are a plethora of benefits to farming pythons, including the snakes' ability to fast for extended periods of time, their low space and water requirements and minimal waste production. 

Due to their large body size and fast growth rates — and without legs or wings to worry about — pythons are a highly efficient source of meat. The scientists published their findings Thursday (March 14) in the journal Scientific Reports. 

"These animals are extremely good converters of food and particularly protein," study co-author Patrick Aust, a zoologist and research associate at the University of Oxford in the U.K., told ABC News. "Literally, they are specialists [at] making the most of very little."

Python farming is well-established in Asia but is yet to take off in other regions, according to the study. With current livestock production systems struggling to meet sustainability standards and growing demand, however, it may be time to consider alternatives.

Related: Enormous Burmese python killed in Florida Everglades was about to lay 60 eggs

"Over the last two decades, snake farming has expanded," the authors wrote in the study. "Reptile meat is not unlike chicken: high in protein, low in saturated fats, and with widespread aesthetic and culinary appeal."

The researchers monitored the growth rates of newborn Burmese (Python bivittatus) and reticulated  (Malayopython reticulatus) pythons at two farms — one in Thailand's Uttaradit province and the other in Ho Chi Minh City, in Vietnam. Despite receiving food only once per week, both species grew rapidly and put on up to 1.6 ounces (46 grams) per day over a period of 12 months — by which time they can be slaughtered for meat, skins and other products. Female pythons grew larger than males, likely due to natural sex differences. 

The researchers fed the pythons a variety of diets, including thawed frozen chicken, wild-caught rodents, fishmeal, chicken pellets and waste products from pork production.

Roughly a quarter of the food ingested by the snakes was converted to meat, regardless of which diet they were fed, and 82% of the snakes' body mass was edible meat by the end of the experiment. For comparison, the meat harvested from cattle generally amounts to about 63% of a cow's weight.

"In terms of food and protein conversion ratios, pythons outperform all mainstream agricultural species studied to date," the researchers wrote in the study. "Production efficiencies for pythons were higher than those reported for poultry, pork, beef, salmon, and crickets."

Pythons also maintained their body mass during periods of fasting that lasted as long as 127 consecutive days thanks to their flexible metabolism. Adult Burmese and reticulated pythons can weigh more than 220 pounds (100 kilograms) and females can produce up to 100 eggs per year, meaning they are "well suited for commercial production," according to the study. 

The researchers highlighted the potential role of python farming in controlling rodent pests and upcycling waste products from other meat industries and agri-food supply chains, if the snakes are fed a diet rich in rodents and waste protein.

The only remaining hurdle to putting python meat on dinner plates is a limited understanding of how to keep thousands of these snakes in captivity, the authors wrote — that, and "the general fear humans have toward snakes."

Maintaining a balanced diet can be hard enough on Earth, but it's even more difficult in space — especially when you're talking about long-haul missions. Although space-based agriculture has made strides in recent years, growing fresh crops in space is no easy feat, and each bit of food or water stored in a spacecraft adds mass, thus weighing down the vessel during its journey out of orbit.

Scientists recently studied possible nutrient-dense meals fit for long-term space travel, such as potential Mars missions, that both satisfy astronauts' nutritional needs and taste better than existing alternatives. They tested 10 dishes to see which would be the optimal meal for male astronauts; they plan to specifically study meals for female astronauts in the future. The best meal would help space travelers get the calories and variety of nutrients they need during their odysseys and use crops that could be grown in space with minimal water.

Ultimately, the best space meal turned out to be a hearty kale salad, according to their study, published Dec. 13 in the journal ACS Food Science & Technology.

"These assessments are essential steps toward feasibility in long-term human space missions, for example, to Mars," the authors wrote.

Space travelers have different nutritional requirements than people on Earth do. That's because astronauts face unique stressors, including the vibration, noise, weightlessness, cosmic radiation and drastic temperature changes inherent to spaceflight. Research suggests that a male astronaut needs to consume around 2.6 pounds (1.2 kilograms) of food per day to maintain their body weight and energy levels. That diet should include more than double the carbohydrates and proteins than a typical person on Earth would require.

Related: NASA reveals first image of 'space tomatoes' that went missing on the ISS for 8 months, and they're gross

With this in mind, the team assessed a variety of nutrient-dense ingredients using a statistical model, which also measured the foods' capability of being grown in space or stored for a long time in a spacecraft. This model yielded 10 "space dishes"; four were vegetarian, and six were made with plants and meat.

Compared with plants, meat options typically provide a higher concentration of certain key nutrients, such as protein and vitamin B12. However, the storage of animal products "requires a large space for long-term space missions," making them tough ingredients to regularly include in an astronaut's diet, the study's authors wrote. (In addition, there aren't yet efficient methods for growing lab-grown meat, although the field is advancing.)

The team couldn't include baked goods like bread, because crumbs can float around in microgravity and damage equipment in the spacecraft.

Crops, on the other hand, could be grown during space travel. Considering all of these factors, the researchers' models determined that the optimal dish to meet astronauts' nutritional needs while being feasible for space travel is a vegetarian salad made with soybeans, poppy seeds, barley, kale, peanuts, sweet potato and sunflower seeds — but notably, no salad dressing.

"I think their choice was very well done," Kathleen Carter, a nutritional researcher at Central State University in Ohio who was not involved in the study, told Live Science. "I think that as we start extending our time in space, we're going to have to go to more plant-based. We're going to have to be able to grow our own resources."

Beyond nutritional value, the researchers studied another factor in the ideal astronaut meal: taste. They fed four volunteers the optimized space salad and recorded their feedback on its palatability. Overall, the results were positive, with one volunteer saying they "enjoyed the sweet taste of the potatoes and freshness crunch."

However, the researchers flagged some key limitations with this meal option.

While some plants, including Chinese cabbage and tomatoes, have been cultivated in space in recent decades, there still isn't a reliable and efficient cultivation system to maximize output in this environment, they noted in the study. Additionally, the optimized salad is still missing some of the vitamins and minerals an astronaut would need each day, though these could be provided through supplements, the authors wrote.

Future studies should also consider the cultural and individual dietary requirements of each astronaut, Carter said. Their space menu would need to accomodate any allergies, personal preferences or dietary restrictions, she added.

"Different cultures are going to want different types of foods," Carter said. "Making sure that food looks good, that it tastes good [and] that it's something that they really want to eat, in addition to being very nutrient dense, is going to be very important."

The researchers plan to use their models to design meals for female astronauts and to incorporate more crops into its algorithm, according to a statement.

Ever wonder why some people build muscle more easily than others or why freckles come out in the sun? Send us your questions about how the human body works to community@livescience.com with the subject line "Health Desk Q," and you may see your question answered on the website! 

Extinct California grizzly bears weren't the giant, blood-thirsty "hypercarnivores" humans made them out to be, new research has found.

It turns out that the once-abundant grizzly bears were mostly vegetarian and only occasionally indulged in livestock after European colonizers and American settlers began farming in California. Contrary to popular belief at the time, these grizzlies also didn't grow to monstrous proportions and rarely, if ever, tipped the scales at the oft-cited number of 2,000 pounds (900 kilograms).

The last reliable sighting of a California grizzly bear (Ursus arctos californicus) dates to 1924, and the subspecies of brown bear likely went extinct soon after. Historical sources consistently paint California grizzlies as murderous beasts — but these records are more accurate representations of prevailing attitudes toward wildlife at the time than they are of the bears themselves, according to a study published Wednesday (Jan. 10) in the journal Proceedings of the Royal Society B. 

"By the time the California grizzly went extinct, it had been featured in a vast archive of documents and images," which suggested the bears attacked people and decimated livestock, researchers wrote in the study. "While these things were true in some ways, it was certainly not the whole story," lead author Alexis Mychajliw, an assistant professor of biology and environmental studies at Middlebury College in Vermont, told Live Science in an email.

Farms mushroomed across the state during the Spanish Missions and Mexican Rancho period, between 1769 and 1848, driving grizzlies into shrinking pockets of habitat. The Gold Rush of 1849, followed by California's admission as a U.S. state in 1850, sparked waves of immigration that put further pressure on bears.

Related: Half-asleep bears are wandering around Siberia because it's too hot to hibernate

For the study, the researchers measured the abundance of stable versions, or isotopes, of nitrogen and carbon in California grizzly pelts and bones. Isotopes vary depending on the food source and are incorporated into an animal's tissue via its diet, meaning they can reveal what the creatures ate.

The results indicated that grizzly bears were largely veggie both before and after the first Europeans arrived in the state in 1542, which is consistent with the diet of modern brown bears.

But California grizzlies more than doubled their meat consumption after the first settlers arrived. Meat from livestock and wild terrestrial animals shot up from 9% of their diet before 1542 to 26% after Europeans set foot in California, according to the study. "The bears likely increased meat consumption due to landscape changes coupled with the arrival of a new source of protein — livestock," Mychajliw said. 

This dietary shift was inflated in contemporary accounts, which encouraged widespread persecution of California grizzly bears and eventually led to their extinction, according to the study.

Newspapers also wildly exaggerated the size of California grizzlies. When the researchers measured skulls and teeth from natural history collections, they found the extinct bears weren't any larger than grizzly bears (Ursus arctos horribilis) that live in North America today and the average one probably weighed around 440 pounds (200 kg). 

Historical overestimates could be due to hunters targeting the biggest bears. "The bears reported in newspaper clippings were often killed as trophies, as part of publicity stunts, or even sold for meat," the researchers wrote in the study. "Therefore, there were both monetary and reputational incentives to both capture the largest animals possible and to exaggerate the size and aggressiveness of captured animals."

The researchers highlighted the sad story of Monarch, a California grizzly bear captured north of Pasadena in 1889 as part of a publishing stunt. Convinced that grizzlies were voracious meat-eaters, zookeepers fed Monarch a rich diet of raw beef, apples and biscuits, which caused the bear to become obese and develop osteoarthritis. "When Monarch died he weighed 1,127 lbs (511.2 kg), more than twice the size of the average California grizzly in our sample," the researchers wrote.

A 4,000-year-old stone-lined tomb discovered during construction work in Norway may provide new clues about the first farmers who settled the region, archaeologists say.

Since April, researchers from the University Museum of Bergen have been excavating at the site of a new hotel in Selje, on the North Sea coast of southwestern Norway. So far, they have found traces of prehistoric dwellings and trash heaps full of animal bones, along with a stone tool called a blade sickle and tiny shell beads. But the most unique find is a large stone-lined tomb that held the skeletons of at least five people.

The burial, which archaeologists call a cist tomb, has been carbon dated to between 2140 and 2000 B.C., or the end of the Neolithic period. Measuring about 10 feet by 5 feet (3 meters by 1.5 m) and nearly 3 feet (1 m) tall, the tomb has two chambers with evidence of burials, including the remains of an elderly man with arthritis, a 2-year-old toddler and a young woman. Additional clustered bones suggest two other individuals' remains had been moved aside to bury new people.

Related: Stunning reconstruction reveals 'lonely boy' with deformed skull who died in cave in Norway 8,300 years ago

While humans invented agriculture around 12,000 years ago in the Middle East, the technique was slow to reach Norway, where people spent millennia living a more nomadic hunting and fishing lifestyle. Two big areas of interest in Norwegian archaeology are how the idea of agriculture took hold and who the earliest farmers were. The Late Neolithic date of the burial along with the presence of a blade sickle, which may have been used to harvest grain, provides strong evidence that Selje was settled by some of the first farmers in western Norway.

"The Selje cist, with its amount of bones, gives [us] a unique opportunity to look into the first groups of individuals who became farmers, as it is "the first of its kind on the west coast of Norway," Yvonne Dahl, a member of the University of Bergen archaeology team, told Live Science in an email.

During the Late Neolithic period, people in southwestern Norway typically buried their dead in rock shelters. But in the eastern part of Norway, where people were already practicing agriculture, cist graves like the one at Selje are much more common. Archaeologists have long assumed that the stone cist funeral tradition originated on the Jutland peninsula of Denmark before farming communities brought it to Sweden and Norway.

Planned DNA testing of the Selje skeletons may be able to confirm whether these people migrated to the west with farming knowledge gained from the east, or whether they are a local group of people who chose a farming life. The future tests should reveal whether, as expected, the people in the tomb are biologically related to one another.

Even though Selje is located on the coast, where the sea in winter makes traveling nearly impossible, "the site is clearly a meeting point for people," Dahl said. "Widespread exchange of both people, ideas, and goods must have been the case during those many thousands of years."

The development of farming by Homo sapiens may be the most fundamental advance of our species. It forever changed the nomadic hunter-gatherer lifestyles that all humans had followed until that time, and the farming practices established by our ancient ancestors still shape agriculture around the world today, feeding billions of people.

Farming also led to villages and then to specialized labor, and then to the advancements of arts and technologies.

But when did farming start? And why?

Related: Are humans at the top of the food chain?

Fertile Crescent

Some of the earliest evidence for farming comes from the Fertile Crescent, a region roughly covering where Iraq, Syria and Israel are today.

Although it's relatively dry now, the region was once well-watered by two major rivers, and some of the first traces of farming were found in Tell Abu Hureyra in northern Syria, which about 11,700 years ago was a village on the banks of the Euphrates River.

Scientists have found signs rye was cultivated there at that time, and that it was deliberately ground into flour with large stones.

Anthropologist and archaeologist Melinda Zeder, a curator emeritus at the National Museum of Natural History, told Live Science that farming seems to have developed in stages: people first cultivated plants in addition to hunting and gathering, then increased their reliance on farm plants, and then settled in nearby villages to dedicate themselves to farming.

"In the Near East, we have about another 1,000 years before we get to what you would call agriculture — when people devote most of their productive labor to growing domestic plants and animals," she said.

Animals everywhere

Following the development of crop farming, domestic animals like sheep, goats and pigs soon became a feature of settled farming life.

Zeder said that goats and sheep were domesticated in the Fertile Crescent about 10,500 years ago. Not too far away, in Anatolia (modern-day Turkey), animal domestication occurred in three major phases about 8,400 years ago, according to a 2022 study in the journal PNAS: first, people in settlements captured wild lambs and kids seasonally and raised them for slaughter; second, residents did limited breeding with these animals while continuing to capture wild young; and third, large-scale herding with reproducing captive animals took place, with adult animals being harvested for the settlement.

Like the domesticated varieties of wild plants, these animals were more suited to farming than wilder animals like gazelles, which were also abundant in the region at the time.

"It was basically the same process as for plants," Zeder said. "These were the resources encountered in these environments that were responsive to farming."

Before farming

Hugo Oliveira, a geneticist at the University of Algarve in Portugal, told Live Science that humans harvested edible plants at certain times of the year long before they developed true farming.

One example is a 10,000-year-old campsite in Germany where people gathered every fall to harvest hazelnuts — thousands of years before farming was introduced into Europe from Anatolia. 

Researchers once theorized that farming started in the Fertile Crescent and spread from there to neighboring regions. But that isn't now thought to be the case, Oliveira said.

Instead, experts now think that farming was developed independently in different places at different times — in western Asia about 11,700 years ago, in eastern Asia up to 9,000 years ago, and in the Americas up to 10,000 years ago.

In every case, farming seems to have started with two key plants — one a cereal, such as wheat or maize, and the other a legume or bean, such as chickpeas or soybeans.

"The cereal gives you carbohydrates, and the legume gives you protein," Oliveira said.

Zeder said it wasn't clear just why farming started when it did, and not in an earlier epoch.

But it seemed to have arisen in the early Holocene — the current time period that started about 12,000 years ago, following the last ice age — through a confluence of factors, including the greater density of human populations at that time and the suitability of plants and animals for farming.

"It’s not a single factor," Zeder said; "it’s density, it's what's available — it's culture."

Scientists have successfully grown watermelons in an unlikely place: Antarctica.

The agricultural feat was part of an experiment at Vostok Station, a year-round Russian research station located at the Pole of Cold, so named because it's classified as the coldest place on Earth, where recorded temperatures once reached a frigid minus 128.6 degrees Fahrenheit (minus 89.2 degrees Celsius).

Watermelons arose in what is now Sudan more than 4,300 years ago and show up in the region's ancient artwork, including at an Egyptian tomb in Saqqara. In other words, the berry evolved far away from the frigid environment of Antarctica. 

To make Vostok Station's greenhouse more hospitable to watermelons, researchers from the Russian Antarctic Expedition of the Arctic and Antarctic Research Institute (AARI), alongside colleagues from the Agrophysical Research Institute and the Institute of Biomedical Problems of the Russian Academy of Sciences, created an oasis where they could increase the air temperature and humidity to conditions that were favorable to the juicy fruit.

Related: Oldest plant genome on record came from a Stone Age watermelon that grew in the Sahara

The team purposely selected two varieties of early-ripening watermelons not only for their delicious taste but also for their ability to adapt to the low atmospheric pressure and lack of oxygen inside the greenhouse. They planted the seeds in a thin layer of soil substitute and used special lighting that mimicked sunlight. Because there were no insects to pollinate the plants, the researchers were tasked with pollinating everything by hand, according a translated statement from AARI.

Exactly 103 days after planting the seeds, the researchers were greeted by eight "ripe and sweet fruits" growing across six different plants. The melons grew to be up to about 2 pounds (1 kilogram) each with diameters of up to 5 inches (13 centimeters), according to a translated statement from the Russian Geographical Society.

Not only was the experiment successful in proving that, under the right conditions, watermelons can be grown in the coldest spot on the planet, but it also provided an exciting snack to the scientists living in Antarctica's harsh conditions.

"Naturally, all polar explorers were glad to remember the taste of summer," Andrei Teplyakov, lead geophysicist of the AARI, told the Russian Geographical Society. "Even the observation of seedlings, growth and the appearance of fruits … [elicited] positive emotions."

This isn't the first time that produce has been grown at Vostok Station. In 2020, researchers successfully grew a variety of plants, including dill, basil, parsley, arugula and cabbage, according to the statement. 

And in 2021, Korean scientists grew watermelons at King Sejong Station in West Antarctica, which had a lowest recorded temperature of minus 78.1 F (minus 25.6 C), according to The Korean Bizwire. 

Next up on the menu, the scientists plan to farm a variety of fruit, including blackberries, blueberries and strawberries.

When deprived of water or snipped with scissors, plants emit a flurry of staccato "screams" that are too high-frequency for humans to hear, a study suggests. When lowered into a range that human ears can detect, these stress-induced pops sound like someone furiously tap dancing across a field of bubble wrap.

Although humans cannot hear these ultrasonic pops without technological assistance, various mammals, insects and even other plants may be able to detect these noises in the wild and respond to them, researchers reported Thursday (March 30) in the journal Cell. (The same researchers first shared their popping-plant discovery in 2019 on the preprint database bioRxiv, but the work has now been peer-reviewed.) 

In the future, humans could harness recording devices and artificial intelligence (AI) to monitor crops for these signs of dehydration or disease, the scientists suggest. 

Past research revealed that drought-stressed plants undergo a process called cavitation — where air bubbles form and collapse within the plant's vasculature tissue — which makes a popping sound that can be detected by recording devices attached to the plant. But it wasn't clear if such popping sounds could be heard at a distance, the authors wrote in Cell. 

Related: Otherworldly 'fairy lantern' plant, presumed extinct, emerges from forest floor in Japan

So the team set up microphones near healthy and stressed tomato (Solanum lycopersicum) and tobacco (Nicotiana tabacum) plants, both in a soundproofed box and in a greenhouse setting. The stressed plants were either dehydrated or had their stems snipped. The team also recorded pots with only soil in them, to check that soil, alone, didn't make any sounds. (They found it didn't.)

On average, healthy plants let out less than one pop per hour, but the stressed plants emitted about 11 to 35, depending on the plant species and stressor. Drought-stressed tomato plants were noisiest, with some plants emitting more than 40 pops per hour. 

The team fed these recordings into a machine-learning algorithm — an AI system used to identify patterns in data — and found that the trained algorithm had about a 70% success rate in distinguishing the sounds made by different plants exposed to different stressors. They trained another AI system to differentiate between drought-stressed and healthy tomatoes in a greenhouse with more than 80% accuracy. Another model could tell what stage of dehydration a plant was in with about 80% accuracy.   

In additional experiments, the team successfully recorded sounds from diseased tomato plants infected with tobacco mosaic virus, and captured the cries of a slew of other stressed plants, such as wheat (Triticum aestivum), corn (Zea mays) and pincushion cactuses (Mammillaria spinosissima). 

Although the researchers gathered these recordings by setting microphones about 4 inches (10 centimeters) away from the plants, they suggest that these ultrasonic sounds could potentially be heard by mammals and insects with great hearing from 9.8 to 16.4 feet (3 to 5 meters) away. 

"These findings can alter the way we think about the plant kingdom, which has been considered to be almost silent until now," the study authors wrote. 

The dairy cows wobbled unsteadily on their hooves, their tongues lolled about and the membranes of their eyes reddened. What triggered these odd symptoms? A diet of industrial hemp, researchers say. 

The cannabis-derived product didn't give cows the munchies — in fact, the cows decreased their overall food intake. In turn, they produced less milk, but the milk they did yield contained detectable levels of both delta-9-tetrahydrocannabinol (THC), the primary high-inducing compound in marijuana, and cannabidiol (CBD), which exerts some effects on the body but isn't psychoactive.   

Hemp is not yet an acceptable animal feed additive in the U.S. or Europe, in part due to concerns that the plants' active compounds will find their way into milk, senior author Robert Pieper, temporary co-head of the Safety in the Food Chain department at the German Federal Institute for Risk Assessment, told Live Science in an email. But as the hemp and CBD industries have grown, stakeholders and regulators have theoretically considered using hemp as animal feed, citing its cheapness and nutritional value, Science reported. However, there's not yet enough research to approve the plant for such use.

In a new study, published Monday (Nov. 14) in the journal Nature Food, Pieper and his colleagues found that cannabinoids can slip into the milk of hemp-fed cows, but the risk this could pose to consumers remains unclear. 

Related: Marijuana's history: How one plant spread through the world  

To evaluate the effects of hemp on dairy cows and their milk, researchers fed 10 lactating dairy cows feed containing hemp with different concentrations of cannabinoids, meaning cannabis-derived compounds with drug-like effects. Hemp and marijuana come from the same plant species — Cannabis sativa — but by definition, hemp contains no more than 0.3% THC, while marijuana carries higher concentrations, according to the U.S. Food and Drug Administration (FDA). 

In the first week of the trial, researchers swapped some of the cows' corn-based feed for hemp feed made from whole C. sativa plants, which contained low doses of cannabinoids. Then, for the next six days, they fed the cows a high-cannabinoid hemp feed made from flowers, leaves and seeds of the plants. 

The whole-plant feed had no effect on the cows' health or behavior. But within hours of switching to the flower feed, the bovines' breathing and heart rates fell unusually low. These are "rare symptoms in cows that only occur in the course of serious illnesses or can be pharmacologically induced," the researchers noted. 

The cows drooled, yawned and produced more nasal secretions than usual, and their eyes reddened. They also exhibited "pronounced tongue play." Some cows who ate larger amounts of the flower feed developed an unsteady gait and adopted abnormal postures when they stood still.

Two days after the diet switch, the cows stopped eating as much, and their milk yields declined. "We currently do not have a mechanistic explanation" as to why this occurred, Pieper told Live Science. The flower feed happened to contain more fat than the whole-plant feed, so that could have affected the cows' appetites — but the cannabinoids themselves also may have played a role, the researchers wrote.

The observed changes in the cows resolved within two days of them switching back to their normal diet. THC is the most likely culprit behind the changes, but other cannabinoids and chemicals in the hemp may have contributed to the cows' symptoms.

THC, CBD and other cannabinoids could be detected in the cows' milk at the end of the whole-plant trial and throughout the flower feed trial. Eight days after the latter trial ended, detectable THC and CBD still lingered in the animals' milk. 

The amount of THC detected during the flower feed trial could have some effect on human health, the study authors said. However, at this point, it's not clear if such THC-tainted dairy would get you high. Much more research will be needed before regulators can consider approving hemp as animal feed. 

Scientists have sequenced the oldest plant genome on record, and it comes from watermelon seeds chomped on by Stone Age sheep herders in the Sahara, a new study finds.

The 6,000-year-old watermelon seeds resurfaced in the 1990s during an archaeological dig of the cave site, known as Uan Muhuggiag, located along a swath of the Sahara that is now Libya. Due to the cave's dry, salty air, the seeds, which may have fallen to the ground during a meal, were well preserved, enabling scientists from the Royal Botanic Gardens, Kew, in the United Kingdom, to sequence their DNA, according to a study published July 30 in the journal Molecular Biology and Evolution.

Examination of the genome also showed that the seeds were those of a wild watermelon, one of Africa's oldest crops, and probably contained a "sickeningly bitter pulp." The discovery is important because it offers information about the domestication of the watermelon (Citrullus lanatus), which translates "to eat something sweet," that we enjoy today. It also offers insight into ancient people's diets and lifestyles, according to Smithsonian Magazine.

Related: Where did watermelons come from?

As part of the study, researchers also sequenced the genomes of dozens of watermelon species that are part of Kew Garden's extensive collections. The scientists discovered that the herders either intentionally collected or cultivated this bitter-fleshed watermelon, a finding that's consistent with teeth marks found on some of the oldest seeds collected in Sudan, according to the study. 

In a separate study, researchers identified the genetic mutations that gave ancient watermelon its bitter compounds, along with today’s recognizable bright-red flesh. However, it's unknown at what point in history that watermelon began resembling the fruit found in modern-day grocery stores.

Which begs the question, why would anyone want to eat the seeds from such a bitter fruit?

"The seed is high in edible fats, and it's storable and transportable," Dorian Fuller, an archaeologist and botanist at University College London, who was not involved in the new study, told Smithsonian Magazine. "We often think of watermelon seeds or pumpkin seeds as snacks, but there's no reason why in some cases they might be cultivated in part primarily for the seed."

Skeletal and mummified ancient remains from the Atacama Desert in what is now Chile show evidence of a surge of extreme violence tied to the rise of farming, a new study finds.

The team analyzed the remains of 194 people who lived between 1000 B.C. and A.D. 600 in the Atacama Desert, and found that while violence was more prevalent at the beginning of the transition to farming, it persisted even after farming villages had been around for hundreds of years. Moreover, the violence targeted men and women alike.

For instance, one woman appears to have been tortured; the skin on her face was stretched so much that her "mouth" was pulled high above its natural position. This was likely an "intentional act, occurring at the time of death when the skin was still fresh and causing deep agony," the researchers wrote in the study, published in the September issue of the Journal of Anthropological Archaeology. 

It's likely that farming — which led to permanent settlements, population spikes, territorial claims, new health problems and social inequity — completely changed how communities interacted with each other, triggering "social tensions, conflict and violence," the researchers wrote in the study. 

Related: Photos: Hundreds of mummies found in Peru

Before farming took off, the ancient people along the coast of the Atacama Desert spent about 9,000 years hunting, fishing and gathering. But around 3,000 years ago, the desert's inhabitants began raising crops and animals. While larger settlements took root in some Andean regions around this time, such as in Caral-Supe on the central coast and Chavín in the central sierra, the villages in the hyperarid Atacama remained small, likely because there wasn't enough fertile land and water to fuel more growth.

"Habitable land in that area is really marginal," said James Watson, the associate director and a curator of bioarchaeology at Arizona State Museum and a professor of anthropology at the University of Arizona, who wasn't involved with the study. "You've got this narrow valley that you can farm in and you've got this very narrow coastline that you can live on and split the coastal resources." 

On top of competing for limited resources, it's possible that the ancient people of the Atacama Desert engaged in cycles of violence, like the Hatfields and McCoys did, Watson added.

To learn more about the violence from this era, the study researchers examined the remains of ancient people previously discovered in six cemeteries in the Atacama's Azapa Valley.

"Although this valley was small, it was one of the richest and most fertile in northern Chile," the researchers noted in the study.

Chilling traumas

Of the 194 adult remains studied, 21% (40 individuals) had traumas that likely came from violence. Of the males, 26% (27 out of 105) had trauma compared with 15% (13 of 89) of the women, a difference that is not statistically significant, meaning that men and women were just as likely to suffer from traumatic injuries, the researchers found.

The majority (51%) of those injured had head trauma, whereas 34% had injuries just on their bodies and 15% had both head and body trauma. Men were significantly more likely to have head traumas than women were, the researchers found. 

However, not all traumas immediately led to death. In 20 cases (50%), the traumas showed signs of healing, especially among younger people and adults ages 20 to 45 years old. That said, one woman had both a healed and an unhealed trauma, showing that she was attacked more than once. But more of the men (75%) had unhealed traumas than the women (25%), indicating that more men died close to the time of injury.

Perhaps the males' trauma came from intense brawls or fights that involved weapons, such as spear throwers, slings, maces, sticks and knives, the researchers said. It's possible that the women were injured due to domestic violence, they wrote in the study.

There were all kinds of injuries, the team found. One man had a projectile stone point embedded in his left lung. Several people had mutilated remains, including the adult woman with the stretched facial skin. In another case, a man had fractured leg bones and fractured toes on his left foot, "which may indicate that the toes were intentionally severed (the right toes were undamaged)," the researchers wrote in the study.

Related: 25 grisly archaeological discoveries

Who was doing the violence?

Of the nearly 200 ancient individuals, the team did a chemical analysis on 69 of them to see if they were local to the area. This analysis looked at the ratio of strontium isotopes (variations of the element) in the deceased individuals' remains. When a person eats and drinks, the strontium isotopes, which are unique to each region, end up in the person's bones and teeth. By comparing the strontium isotopic ratios in people with those in the environment, researchers can determine where ancient people grew up.

Of the 69 people, 26 were native to the Atacama Desert, whereas 42 had results showing that they ate foods beyond the local area, including marine animals. "As such, conflict and violence likely occurred between groups of horticulturalists who were colonizing the Azapa Valley and fishermen living on the adjacent coast," the researchers wrote in the study. The woman with the mutilated face was the only foreigner, and likely came from what is now southern Peru, according to her isotopic ratios and distinctive tattoos.

Violence in the Atacama existed before farming, of course. Perhaps this violence among farmers was a result of "strong competition among local groups to secure and maintain access to new productive land and spring water for irrigation," the researchers wrote in the study.

Despite this, violence decreased as time went on. The early period (600 B.C. to A.D. 1) had double the frequency of trauma than did the late period (A.D. 1 to 600), the team found. Perhaps the "emergence of social practices that regulated conflicts" tied to property rights helped to quell the violence, they wrote.

It's also possible that the particular pattern of La Niña and El Niño climate cycles at the time contributed to fierce competition in the Atacama Desert. The climate trends at the time likely made marine resources scarce, which added pressure on farmers to produce food for the growing population, previous research suggests.

On top of the turbulent social transitions and competitions that came with farming, emerging leaders may have also made power grabs to enhance their prestige and wealth, the researchers said. All of this led to "potentially lethal trauma" that rocked the region. 

Originally published on Live Science.

Three men in Ohio died this week after entering a manure pit and passing out from the fumes, according to news reports. 

The men, who were brothers, had entered the manure pit to fix a pump, according to local news outlet KDKA. They were knocked unconscious by the fumes and became trapped in the pit, where first responders found them on Tuesday (Aug. 10), KDKA reported. The men were rescued and taken to local hospitals. All three men died at the hospital that same day, according to Insider.

Manure pits, which are used to store animal waste for use as fertilizer, produce toxic gases that can be deadly. Decomposing manure produces hydrogen sulfide, methane, ammonia and carbon dioxide, all of which can be hazardous to humans and animals at high concentrations, according to the National Agricultural Safety Database (NASD).

Related: What is tear gas?

The most dangerous of these gases is hydrogen sulfide. At low levels, the gas gives off an odor of rotten eggs, and causes eye and throat irritation, according to NASD. At moderate levels, exposure causes headache, nausea and dizziness. As concentrations of the gas increase, it paralyzes nerve cells inside the nose, and causes a loss of smell, NASD says. This means a person can't rely on their nose to detect dangerously high levels of hydrogen sulfide.

When the manure in the pit is agitated or pumped for use, levels of hydrogen sulfide can quickly rise from 5 parts per million (ppm) to more than 500 ppm, a level that can lead to unconsciousness. Breathing hydrogen sulfide at levels above 600 ppm can cause death in just one or two breaths, according to NASD.

Exposure to the ammonia in manure pits can cause eye and throat irritation, wheezing and shortness of breath. 

In addition, both methane and carbon dioxide are dangerous because they can displace oxygen inside an enclosed space, leading to asphyxiation.

People who enter manure pits should take necessary safety precautions. Such precautions include testing gas levels with a meter before entering, or wearing a self-contained breathing apparatus (SCBA) and a safety harness. It's also important for people who attempt to rescue those trapped in a manure pit to wear protective equipment, according to NASD.

"Unless the rescuer is wearing SCBA protective equipment ... there is a strong likelihood that the rescuer will also succumb to the toxic gases or lack of oxygen. There have been numerous instances where several farmers have been killed while attempting to remove someone from a pit or facility," according to the NASD.

"Always treat a [manure] pit as if it is a death trap," the website says.

Originally published on Live Science.  

The iconic green and red watermelon is a sweet, refreshing summer staple. But it wasn't always so sugary or vibrantly colored. So what did watermelons originally taste and look like, and from where did they originate?

The thirst-quenching fruit isn't from the Fertile Crescent of ancient Mesopotamia, as so many other domesticated crops are, research shows. Susanne Renner, a botanist at Ludwig Maximilian University of Munich in Germany, and her colleagues carried out comprehensive genetic sequencing of the domesticated watermelon (Citrullus lanatus) — the kind you might find on supermarket shelves — along with six wild watermelon species. 

"We found the modern genomes of the domesticated watermelon are more closely related to the Sudanese wild type than any other that we analyzed," she told Live Science. The Sudanese wild watermelon has some notable differences to the domesticated version. "The flesh is white and not very sweet, and it's mainly used as animal feed," Renner said. 

Nevertheless, the genetic similarity between the two species led the researchers to conclude that the Sudanese fruit is probably a precursor to the red and sweet domesticated watermelon, according to the June 2021 study published in the journal the Proceedings of the National Academy of Sciences.

Related: Are carrots orange because of a Dutch revolutionary?

It's likely that ancient farmers cultivated non-bitter variants of the wild watermelon and consequently increased its sweetness over many generations through the domestication process. The red color is probably also thanks to artificial selection, in which farmers likely favored and selectively bred red fruit. When this happened and which civilization is responsible for it is slightly less clear, but Renner attempted to answer this question. She thinks the geographical location of the close wild type relative in Sudan is probably not a coincidence. 

We already knew that the ancient Egyptian king Tutankhamun was buried with watermelon seeds 3,300 years ago, but that isn't sufficient proof of a domesticated, sweet watermelon. "The seeds may have been used as savory snacks from a wild watermelon,"  Renner said. 

But then, she found an image of a watermelon-like fruit on an ancient Egyptian tomb painting, thought to be more than 4,300 years old. "The image was originally published back in 1912, but nobody had interpreted it as a watermelon before," Renner said. In a separate tomb, "another image shows the watermelon cut up on a tray alongside other sweet fruits, such as grapes." This realization, coupled with Renner's genetic findings, begin to paint a picture of ancient Egyptians enjoying domesticated and sweet watermelons. That, in turn, suggests that the watermelon was most likely domesticated around that time either in Egypt or within trading distance of the ancient empire. 

"The ancient Nubians who lived in modern-day Sudan are often overlooked in favor of the Egyptians," Renner said. "It could have been the ancient Numbians who domesticated it and traded it with the ancient Egyptians or it could have been the Egyptians, but what my research suggests is that it was somewhere in this region that the watermelon was first domesticated, and the ancient Egyptians were eating them." 

Historically speaking, that's a very significant finding, said Hanno Schaefer, a professor of plant biodiversity at the Technical University of Munich. "It's becoming clearer that we've massively neglected the North African region. We've focused too much on the Fertile Crescent where grains and pulses [edible legume seeds] seem to have originated, but we need to invest more resources into studying the agriculture of North Africa and add those findings to the archaeological evidence," Schaefer told Live Science.

Studying the wild relatives of domesticated crops has an application beyond historical curiosity; it could prove helpful for modern-day breeders and farmers. "There are many traits of wild populations that would be useful in watermelon breeding — they're less susceptible to mold, viruses and insects than domesticated species," Renner said. Knowing more about wild watermelon DNA could help breeders take those beneficial gene variants and implant them into the modern crop without compromising the watermelon's sweet taste and red hue, which has taken so long to acquire through selective breeding. 

This could potentially enable watermelon farming to weather the future challenges that climate change will bring, such as drought and higher temperatures, Schaefer said. "I'm sure the industry will be interested in studies tackling the genetics of watermelon."

Originally published on Live Science.

Editor's note: This research was originally published in 2019 to the preprint database bioRxiv and was then published in the peer-reviewed journal Cell on March 30, 2023.  

In times of intense stress, people sometimes let out their angst with a squeal ⁠— and a new study suggests that plants might do the same.  

Unlike human screams, however, plant sounds are too high-frequency for us to hear them, according to the research, which was posted Dec. 2 on the bioRxiv database. But when researchers from Tel Aviv University in Israel placed microphones near stressed tomato and tobacco plants, the instruments picked up the crops' ultrasonic squeals from about 4 inches (10 centimeters) away. The noises fell within a range of 20 to 100 kilohertz, a volume that could feasibly "be detected by some organisms from up to several meters away," the authors noted. (The paper has not been peer reviewed yet.)

Animals and plants might listen and react to the silent screams of plants, and perhaps humans could too, with the right tools in hand, the authors added. The idea that "sounds that drought-stressed plants make could be used in precision agriculture seems feasible if it is not too costly to set up the recording in a field situation," Anne Visscher, a fellow in the Department of Comparative Plant and Fungal Biology at the Royal Botanic Gardens in the U.K., told New Scientist.

Like animals, plants respond to stress in a variety of ways; studies suggest that plants may release smelly chemical compounds or change their color and shape in response to drought and bites from hungry herbivores. Animals seem to recognize and respond to these botanical stress signals, and even other plants appear to pick up on the airborne scents wafting from their tense neighbors. Some previous research had suggested that plants react to sound, too, but questions remained about whether plants themselves emit detectable noises.  

Related: The Worst Droughts in U.S. History

In previous studies, researchers affixed recording devices directly to plants to listen for secret sounds inside their stems. In plants stressed by drought, air bubbles formed, popped and triggered vibrations within the tissue that normally carries water up the plants' stems. The process, known as cavitation, was picked up by the attached recording devices, but the Tel Aviv researchers wanted to know if any plants sounds could travel through the air.      

So the team set up microphones near stressed-out tomato and tobacco plants placed in either a soundproof box or an open greenhouse space. The researchers subjected one set of crops to drought conditions and another to physical damage (a snipped stem). A third untouched group served as a point of comparison. 

The recordings revealed that the different plant species made distinct sounds at varying rates, depending on their stressor. Drought-stressed tomato plants emitted about 35 ultrasonic squeals per hour, on average, while those with cut stems made about 25. Drought-stressed tobacco plants let out about 11 screams per hour, and cut crops made about 15 sounds in the same time. In comparison, the average number of sounds emitted by untouched plants fell below one per hour. 

Given the variation in noises among the groups, the researchers wondered if they could identify each plant based solely on its signature screams. Using machine learning — a type of artificial intelligence algorithm — the team picked out distinct features in each set of sounds and successfully sorted their plants into three categories: "dry, cut or intact." Someday, farmers could use a similar technology to listen for drought-stressed crops in their fields, the authors suggested.

Related: Plant Photos: Amazing Botanical Shots by Karl Blossfeldt

In this study, the authors did not test whether plants exposed to disease, excess levels of salt or unfavorable temperatures also emit sound, so it remains unknown whether all stressed plants squeal. However, the researchers did record similar sounds in other cut or drought-stressed plants, including spiny pincushion cacti, and henbit deadnettle weeds. Insects, such as moths, may listen for sounds emitted by stressed plants to assess their condition before laying eggs on their leaves, the authors suggested.

Until the scientists observe how and whether moths react to plant noises, this conclusion remains speculative, the authors added — in fact, one outside expert said the idea may be a "little too speculative." 

Edward Farmer, a professor of plant molecular biology at the University of Lausanne in Switzerland, told New Scientist that insects are known to favor certain plants for a variety of reasons and that he doubts excessive noise is one of those reasons. Furthermore, the new study failed to account for sounds that drying soil may make on its own, as well as other confounding noises that the researchers' microphones may have picked up, Farmer added. 

• Simple Plant Science Experiments for Kids 
• What's That Noise? 11 Strange and Mysterious Sounds on Earth & Beyond 
• 5 Ways Your Cells Deal With Stress 

Originally published on Live Science. 

Bad news for banana lovers: A fungus that's particularly adept at killing the fruit has finally reached Latin America — a major supplier of the world's bananas — as scientists long feared it would.

Recently, officials in Colombia declared a national emergency after confirming the presence of this deadly fungus, known as Fusarium oxysporum Tropical Race 4 (TR4), in the country, according to the Colombian Agricultural Institute (ICA). 

This is the first time the fungus has been detected in Latin America. However, the fungus isn't new — for decades, it has been devastating banana plantations in Asia, Australia and East Africa, Live Science previously reported.

Although this fungus isn't harmful to humans, it is a "serious threat" to banana production, according to the United Nations. The fungus attacks the plant's roots and blocks its vascular system — the network used to transport water and nutrients — and ultimately kills the plant. Once the fungus finds its way into soil, it can't be treated with fungicides, and it's very difficult to remove.

What's more, the fungus attacks the most commonly exported banana, the Cavendish banana. "For Western countries, the vast majority of the bananas we eat are from the same Cavendish subgroup," Nicolas Roux, a senior scientist at Bioversity International in France, told Live Science in a June interview.

Cavendish bananas reproduce asexually, meaning that the plants are essentially clones of their parents. This means banana crops lack genetic diversity, and infections can spread quickly.

"What we're having is an almost apocalyptic scenario where we'll probably lose Cavendish [banana]" Sarah Gurr, Exeter University’s chair in food security, told Wired.

Officials reported that the TR4 fungus was found in a 175-hectare area in the La Guajira region of northern Colombia. The country has quarantined and destroyed affected areas in an effort to fight the fungus.

A number of ideas have been proposed to help save the Cavendish banana, including genetically engineering plants that are resistant to TR4.

•  9 Disgusting Things That the FDA Allows in Your Food 
•  11 Ways Processed Food Is Different from Real Food 
•  27 Devastating Infectious Diseases 

 Originally published on Live Science.

Thousands of years ago, fallout from volcanic activity may have sounded a death knell for a centuries-old Egyptian dynasty, according to a new study.

In Ptolemaic Egypt (305 B.C. to 30 B.C.), the region's prosperity was linked to the flood cycle of the Nile River, with regular flooding sustaining local agriculture. When floods failed, so did crops, and social unrest shook the region.

The new study proposes a link between historic volcanic activity and disruption of the African monsoon rainfall during the summer. A drier monsoon season could have reduced Nile flooding, leading to fewer crops and more food shortages and, ultimately, initiating a societal unraveling that led to the Ptolemaic dynasty's eventual collapse, the study authors wrote. [7 Amazing Archaeological Discoveries from Egypt]

When volcanoes erupt, they spew sulfur-rich gases in plumes that can extend into the stratosphere. These gases then oxidize and form particles called sulfate aerosols that can dramatically impact weather patterns such as monsoons, the study authors reported.

"These aerosols are really effective at reflecting incoming sunlight back to space," study co-author Francis Ludlow, a researcher with the Yale Climate and Energy Institute, told Live Science in an email. 

"Hence, less energy reaches the earth's surface, so we have cooling, and where we have cooling, we also have less evaporation and less potential for rainfall," he said.

Aerosols produced by a volcanic eruption in Iceland, for instance, could thereby sap the heat driving the African monsoon, thus leading to less rain and reduced Nile flooding, Ludlow explained.

A dry season

Piecing together the events in ancient Egypt required delving into the geologic record for evidence of global volcanic activity and comparing that activity to fluctuations in annual Nile flooding, recorded over centuries with structures called nilometers.

"It was already known that the Nile was dependent on the strength of the African monsoon each summer, and that volcanism could alter the monsoons," Ludlow said. The nilometers confirmed that during years when there were volcanic eruptions, the average Nile response was lower flood heights, the researchers found. Next, they needed to see if this finding corresponded to social repercussions.

The scientists compared their data to extensive records from the Ptolemaic dynasty describing episodes of unrest — which were previously unexplained — to see whether these incidents overlapped with volcanism and reduced flooding, Ludlow said.

Archives showed that, in the decade prior to the fall of the Ptolemaic dynasty — which ended with Cleopatra's death in 30 B.C. — Egypt's prosperity had weakened notably, with repeated Nile flooding failure, famine, plague, inflation, corruption, land abandonment and migration taking a heavy toll, Ludlow told Live Science in an email.

Moreover, samples taken from ice cores provided data about volcanic eruptions that aligned with notable social unraveling, the study authors wrote.

For example, a massive volcanic eruption in the Northern Hemisphere in 44 B.C. — the same decade noted in Egyptian records as a period of declining fortunes — was the biggest eruption in 2,500 years, "with 87 percent of the aerosols remaining in the Northern Hemisphere," Ludlow said.

Undermining a dynasty

Because Egyptian agriculture depended almost entirely on summer flooding, interruptions in the floods could devastate crops, thus leading to famines and an increase in social tensions as people grew hungry and desperate. If other social and economic stresses were already at play — elevated taxes or disease outbreaks, for example — this could be enough to tip unrest into a full-blown revolt, Ludlow explained.

Warnings for the present are also written in these historical records, Ludlow added.

Though volcanic activity in recent centuries hasn't rivaled the cataclysmic upheavals of past millennia, that could change "at any time," he said. Explosive eruptions could have a devastating impact on agricultural regions that are presently dependent on monsoons, which would directly impact about 70 percent of the global population, Ludlow said.

"For the Nile, in particular — with tensions already high regarding the sharing of water from the Blue Nile between Ethiopia, Sudan and Egypt — the possibility of diminished supplies following the next big eruption needs to be included in any water-sharing agreements," Ludlow said.

The findings were published online today (Oct. 17) in the journal Nature.

Original article on Live Science.

In the United States alone, hundreds of thousands of poultry farms produced nearly 9 billion chickens for consumption in 2016, according to a report published in April by the U.S. Department of Agriculture (USDA). And all those chickens add up to big profits — a value of about $26 billion, the USDA reported. But the staggering popularity of chicken has come at an enormous cost — to chickens and to people.

The story of the demand for chicken is also a story of antibiotics, which spurred the growth of the chicken industry by literally fueling the growth of chickens, making broilers put on weight more quickly and with less feed. At the same time, greater numbers of chickens raised together in close quarters increased the risk of communicable diseases, encouraging the liberal use of preventative antibiotics to stave off the possibility of epidemics, according to science writer and journalist Maryn McKenna.

Over time, this contributed to an alarming rise in antibiotic-resistant bacteria, leading experts and officials to re-evaluate the way chickens were raised, and to formulate ways to counteract threats from drug-resistant superbugs. [Top 7 Germs in Food That Make You Sick]

McKenna weaves together the intertwined story of industrial chicken farming and antibiotics in her new book, "Big Chicken: The Incredible Story of How Antibiotics Created Modern Agriculture and Changed the Way the World Eats" (National Geographic, 2017). McKenna recently spoke to Live Science about how chickens became such an overwhelmingly popular source of cheap protein; how the demand for chicken, in turn, transformed the use of antibiotics in livestock; and the repercussions that had for human health.

This Q&A has been edited lightly for length and clarity.

Live Science: What was it about chickens that led you down the path to writing this book?

Maryn McKenna: I was looking first at the issue of antibiotics in agriculture, which came from having written a book on antibiotic resistance ["Superbug: The Fatal Menace of MRSA" (Free Press, 2011)]. And in the process of that work, I came across this statistic: In the U.S., we sell four times as many antibiotics for use in animals as we do in people. Having just been listening to people be very emphatic in the medical realm that we have to use antibiotics conservatively, the fact that their caution and alarm could exist in the same time and space as literally tons of antibiotics [were] being given to animals — essentially with no oversight — was startling to me.

As I dug more deeply into it, I realized that this story of antibiotic resistance and use in agriculture was bracketed by the story of how we raise chickens. Chickens were the first animals to get growth-promoter antibiotics experimentally, and chickens are probably going to be the first sector of the protein economy in the United States to exit routine antibiotic use. And it seemed to me that all the things we critique about poultry production — and, in fact, about industrial-scale livestock production — can all be traced back to the use of antibiotics.

Without antibiotics being used, we wouldn't have been able to produce animals so rapidly. We wouldn't have had the impetus to crowd them in barns and feed lots; antibiotics allowed them to be protected from diseases [that might have resulted] from that crowding. Antibiotics created a supply of reliable, inexpensive protein; then demand for it had to be stimulated by things like chicken nuggets and further processed chicken.

And so the more I looked, the more I realized that chickens really told the story of industrial-scale, modern, high-throughput livestock production better than anything else I could find.

Live Science: What were the red flags indicating that antibiotics used in chickens could have consequences for human health, and how did researchers connect the dots to convince policymakers that antibiotics promoting growth or being used for disease prevention in farm animals were making people sick?

McKenna:At the start of the story, nobody thinks that using antibiotics in animals is going to have any downside. To give them credit, the researchers in the late 1940s and early 1950s looked into what the use of antibiotics would do to the animals that were getting them, and concluded that if resistance occurred, then the growth promotion effect or the preventative effect would stop working — and they would know that it wasn't working because animals would cease gaining weight or they would start getting sick. They didn't think to look beyond the animal to see if there was going to be a human effect.

The very first signal that something was going wrong with antibiotics use in agriculture — which I love, because it's just so bizarre — is that in the early 1960s, people complained that children were developing penicillin allergies from drinking milk. And that turns out to be because so much penicillin is going into dairy cattle, that some milk in the U.S. and the U.K. could have been sold as a drug, because it had so much penicillin in it. Then, cheese makers start complaining that they can't make cheese anymore, because there's so much penicillin in the milk that when they put the culturing bacteria in, it kills them, and so the milk doesn't solidify into cheese.

There start to be epidemics of antibiotic-resistant foodborne illness— things like Salmonella and Campylobacter [bacteria] — and that's never been seen before. Big outbreaks that are not tied to a specific geographic area are new, and that they are antibiotic-resistant is very new.

And so a couple of epidemiologists in the U.K. and then in the U.S. do some really yeoman work, trying to track back illnesses from the sick people through the supply chain of what the people ate, back to the processors and then back to farms. That detective work takes a long time, but every time, they ended up back at a farm using antibiotics in its animals, and that happens over and over again.

In the late 1960s, it happened often enough that the British government empanels a commission to examine this issue of farm antibiotic use, and in 1969, they come out with a report that recommends the first-ever government action to stop this use of antibiotics [in all farm animals], which the U.K. does in 1971. 

And then attention turns to the U.S., where there's a seminal experiment in 1976. Dr. Stuart Levy [a researcher at Tufts University specializing in antibiotics use and resistance] sets up an experimental farm on a family's property on the outskirts of Boston, and installs brand-new batches of chickens — widely segregated and unable to mix. He hires a member of the family, and she starts feeding antibiotic-laced feed to some of the chickens, and then watches to see if antibiotic-resistant bacteria are going to show up in those birds, in the other birds that have no contact with the first batch of birds, and in the farm family.

And in each case, that happens.

That's the first controlled demonstration that antibiotics given to farm animals produce antibiotic-resistant bacteria in the guts of the animals that receive them, that those bacteria can move through the environment and enter other animals and reproduce there, and that they can also contact humans.

On that basis, in 1977, the FDA tries to control antibiotics use in animals in the U.S. in the way that the U.K. did, and is prevented by political interference and enters this stalemate that persists until the Obama administration comes along. In that time, more and more, and larger and larger outbreaks happen, and the molecular tools for tracing them get more precise. By the time the Obama administration rolls around in 2010 and decides to change what could not be changed in 1977, the evidence is really incontrovertible that this has been causing negative human health effects.

Live Science: Have we reached a critical tipping point in the evolutionary arms race against drug-resistant bacteria, as some bacteria are already showing resistance to the "last resort" antibiotics in the human arsenal?

McKenna: We are at a point of significant peril, because bacteria are becoming so multiple-drug resistant, and are resistant to most serious "big gun" antibiotics that we have. And agriculture bears some responsibility for that. Not solely; it's important to say there is misuse and overuse of antibiotics in medicine as well. But if we were to stop using these antibiotics, there are indications we could send antibiotic resistance back down the evolutionary pathway.

There are societies that stopped using antibiotics in agriculture, and also slowed down their antibiotics use in medicine — Scandinavian countries and the Netherlands. When they took away the evolutionary pressure on bacteria to keep developing defenses, bacteria gave up some of those defenses, because they no longer needed them. Many mutations that protect bacteria against the action of particular antibiotics are costly to bacteria in an evolutionary sense; they make the bacteria otherwise less fit to survive in whatever niche they are occupying. If bacteria can give those up, they will. If antibiotics pressure goes away, then they no longer need that mutation.

In national surveys in Sweden, Norway, Denmark and the Netherlands, where they do excellent jobs of tracking occurrences of drug-resistant bacteria in humans and animals, you can see that after they gave up or prevented use of certain antibiotics, that the incidence of resistant bacteria is declining. It declines first in animals. And that's very clear; there's very robust evidence for that. And then it starts to decline in humans, too.

That doesn't work for everything. Some research not very long ago showed that bacteria in chickens in the U.S. were hanging on to resistance to a drug that is no longer used in chickens, the lone drug that was removed from the market a while ago. That's probably because it's a mutation that doesn't have any fitness cost [meaning it doesn't impact the animal's survival]. But generally speaking, if you take the antibiotics away, the resistance goes away. So that's one way that we could back ourselves away from the precipice.

Live Science: In recent years, the study of the human microbiome has revealed microbes to be critical players in our body systems. Has that helped to raise awareness in the chicken industry — and in the general public — about the dangers of antibiotics, which can kill helpful bacteria as well as harmful ones?

McKenna: Absolutely. I think that when all this started, we didn't even have the word "microbiome" to indicate what was going on, though it was pretty clear that growth promotion, at least, is a perturbation of the gut microbiome — that's what causes its effects to happen.

There's a widespread understanding now that we live in a microbial world, and everything we do to affect it has unintended consequences. I think that also contributes to this new caution about how freely we dispense antibiotics, because we understand we're setting forth unpredictable ripple effects that are going to perturb this entire microbial conversation in ways that we didn't really understand before.

You can buy "Big Chicken" on Amazon.

Original article on Live Science.

A rare condition called elephantiasis, which tends to strike people in tropical parts of the world, was long thought to occur due to a parasitic infection. But a new study shows that the condition can have another cause: sharp crystals found in certain soils.

In elephantiasis, a person's limbs become discolored and swollen with fluid. They may swell to enormous sizes, resembling the limbs of an elephant. The most common cause of the condition is a mosquito-borne parasitic infection called lymphatic filariasis, in which microscopic worms invade the body's lymph nodes and vessels, causing the swelling.

But in 2014 and 2015, there were reports of two intense outbreaks of elephantiasis in western Uganda, an area that is not known to harbor these worms. [The 10 Most Diabolical and Disgusting Parasites]

Indeed, when the Uganda Ministry of Health investigated the outbreak, the agency identified another cause of elephantiasis: a disease called podoconiosis. And what was thought to be an outbreak of a parasitic disease was far from it; rather, the symptoms of podoconiosis slowly build up over decades, gradually developing into elephantiasis, the study said.

"People can be suffering from podoconiosis, a noninfectious disease, for decades before it becomes obvious that they are developing elephantiasis," lead study author Dr. Christine Kihembo, a senior field epidemiologist at the Uganda Ministry of Health, said in a statement. "Many of the people affected in western Uganda probably had been suffering silently without help for more than 30 years."

In September 2015, Kihembo and her team visited the region to try to determine why people there were getting the disease. Their findings were published published Monday (April 10) in the American Journal of Tropical Medicine and Hygiene.

In the study, the researchers looked at 52 people who had hard, asymmetrical swelling of both legs that lasted for at least one month, along with other relevant symptoms, such as itching or burning in their legs,  rigid toes and skin with a "mossy" appearance, the researchers wrote in the study.

They ran blood tests and ruled out the usual case of this swelling, the parasitic infection called lymphatic filariasis. In 40 of the 52 people with symptoms, the parasite infection was not found. And so the researchers concluded that these 40 people probably had the other cause of the swelling, podoconiosis.  

But what causes podoconiosis? To answer this question, the researchers looked to the soil.

Prolonged exposure to volcanic soil was thought to cause podoconiosis, the study said. When a person spends a lot of time walking barefoot on volcanic soil, mineral crystals penetrate the soles of his or her feet. These crystals make their way into the lymphatic system, and damage it. The lymphatic system, which includes the lymph nodes, is a network of tissues and organs that help rid the body of waste. When the system is damaged, a clear fluid called lymph, which contains white blood cells, can build up, causing the characteristic swelling of elephantiasis.

From interviews with the participants, the researchers learned that about half were farmers. Of these farmers, about two-thirds never wore shoes while farming and two-thirds never washed the soil off their feet during the day, the researchers found. In contrast, most of the people in the control group wore shoes while farming. However, not wearing shoes at home was also associated with developing the disease.

Farming while barefoot was strongly associated with developing the disease, the researchers wrote.

Indeed, the researchers recommended that in the future, the villagers be provided with shoes to help reduce their risk of developing the disabling disease.

Originally published on Live Science.

ATLANTA — Climate change is poised to affect the world's food supply in three key ways, experts say.

"There will be impacts on the quantity, quality and location of the food we produce," said Dr. Sam Myers, a medical doctor and senior research scientist studying environmental health at the Harvard T.H. Chan School of Public Health.

"We've never needed to increase food production more rapidly than we do today to keep up with global demand," Myers told Live Science.

But, "at the very same time, we're fundamentally transforming the biological underpinnings" of how we produce food, he said. [The Reality of Climate Change: 10 Myths Busted]

Researchers studying climate change are looking at how the biological and physical changes happening on Earth due to climate change will transform food production, Myers said at a talk today (Feb. 16), here at the Climate & Health Meeting, a gathering of experts from public health organizations, universities and advocacy groups that focused on the health impacts of climate change.

Food quantity

Ultimately, climate change will reduce the amount of food grown around the world, Myers told Live Science.

Initially, some experts thought that rising carbon dioxide levels might act as a fertilizer and increase food yield, Myers said. However, more recent research suggests that the net effects of climate change will mean a decrease in food yield, he said.

For example, studies have shown that the combination of increased levels of carbon dioxide in the atmosphere, rising temperatures and changes to precipitation may result in significantly lower yields for staple crops such as corn and wheat, particularly in tropical areas, where food production is normally high, Myers said.

Areas that experience increasing temperatures due to climate change will also likely see an increase in crop pests, Myers said. Currently, pests are responsible for 25 to 40 percent of all crop loss, he said, and as climate change continues, these pests will be able to expand their reach. [7 Insects You'll Be Eating in the Future]

Insects may move into areas where they weren't found previously and where plants haven't evolved defenses to ward them off, Myers said. It's also possible that certain predators of crop pests, such as birds, may shift the timing of their migrations because of climate change in ways that could prevent them from keeping pest populations in check, he added.

Location

The location of much of the world's agriculture will also change in ways that affect the global food supply, Myers said.

Agriculture in tropical regions will likely be the hardest hit by climate change, he said. And higher global temperatures will make it more difficult for farmers to work in the heat of the day, leading to less food production, he added. Indeed, existing research already shows that heat limits work at certain times of day depending on the season in certain tropical and subtropical areas, he said.

Other food sources, such as fish, will decrease in quantity, Myers said in his talk. And, as the ocean warms, fish move toward Earth's poles, he said.

The problem with food production decreasing near the equator, he noted, is that almost all of the human population growth that's predicted for the next 50 years will occur in the tropics, Myers said.

And although regions closer to the poles will experience warmer weather and longer growing seasons as a result of climate change, these changes won't be large enough to make up for the loss of food production in the tropics, Myers said.

Food quality

In addition to changes in the amounts and location of food production, research shows that when certain foods are grown at high levels of atmospheric carbon dioxide, they lose some of their nutritional value, Myers said.

Myers and his colleagues first published research on this phenomenon in 2014 in the journal Nature.

In that study, the researchers grew crops, including wheat and corn, under two conditions: elevated carbon dioxide levels, or normal carbon dioxide levels. The elevated carbon dioxide levels represented the concentration that is estimated to be in the atmosphere in 50 years, Myers said. They found that the crops grown under elevated carbon dioxide levels had lower levels of protein, zinc and iron, Myers said.

The decreases in the nutrients could worsen the public health problem of nutrient deficiencies, Myers added. Iron and zinc deficiencies are already huge health problems today. In the future, 200 million more people worldwide could develop a zinc deficiency, and the 1 billion people who already have a zinc deficiency could see their deficiency worsen due to these nutritional changes, Myers said. Research shows that there would be similar effects for iron and protein deficiencies as well, he said.

More research on crop nutrient levels is needed; for example, researchers still aren't sure why elevated levels of carbon dioxide cause crops to lose nutrients, Myers said. [Science You Can Eat: 10 Things You Didn't Know About Food]

The findings illustrate how the effects of climate change are still surprising, even to scientists, Myers said. "Never in a million years would we have" predicted that an effect of climate change would be crops losing their nutritional value, he said.

"There's no way we would've anticipated that," Myers said.

Originally published on Live Science.

Simulated "Martian gardens" are helping NASA scientists learn which plants astronauts might be able to grow on the Red Planet. 

A human round-trip journey to Mars may take as long as two and a half years, and one major challenge for these kinds of extended missions is determining how to pack enough food for those astronauts. As such, scientists are studying ways for astronauts to grow their own crops and extend their food supply, because seeds take up less room and have a longer shelf life on spacecraft than full-grown plants do. 

Simulated "Martian gardens," developed at NASA's Kennedy Space Center and the Florida Tech Buzz Aldrin Space Institute, are helping researchers overcome food production challenges associated with Mars' barren landscape. [Space Food Photos: What Astronauts Eat in Orbit]

Farming on Mars is much different from farming on Earth. Martian soil consists of crushed volcanic rock with no organic material, making it nearly impossible for plant life to survive, according to a statement from NASA.

"We are using advances in science to learn about increasing plant production to supplement astronauts' diets," Trent Smith, project manager for the Vegetable Production System (Veggie) experiment at NASA's Kennedy Space Center, said in the statement. The Veggie experiment has allowed astronauts to garden in space and conduct experiments on plant biology on the International Space Station. 

The soil being used in the "Martian garden" was collected from Hawaii and chosen because it simulates the kind of soil found on Mars. Using this Hawaiian soil, the researchers tested how much soil should be used, and which nutrients should be added to the soil, for the various crops to achieve optimal growth. 

For example, the researchers tested how lettuce grows in the Mars-like soil simulant. They compared their results to lettuce plants grown in the soil simulant with added nutrients, as well as lettuce planted in normal potting soil. This experiment revealed that the lettuce grown in the Mars-like soil simulant with no added nutrients tasted the same but had weaker roots and a slower germination rate (in other words, they took longer to grow), according to the NASA statement. 

In the future, the researchers plan to test how crops such as radishes, Swiss chard, kale, Chinese cabbage, snow peas, dwarf peppers and tomatoes fare in the Martian soil simulant. 

"Discoveries made in these Earth-based 'Martian gardens' will pave the way for future studies and technology development in terms of reliable, efficient food production a long way from the home planet," Ralph Fritsche, senior project manager for food production at Kennedy Space Center, said in the statement. "We're right at the cutting edge of this research."

Follow Samantha Mathewson @Sam_Ashley13. Follow us @Spacedotcom, Facebook and Google+. Original article on Space.com.

Sometimes called the "doomsday vault," the Svalbard Global Seed Vault is seen as humanity's last hope against extinction after a world crisis. Though its mission is to keep the world's seeds safe, its creation wasn't meant as a way to reseed the world after a world-scale catastrophe. 

The Svalbard Global Seed Vault was the brainchild of Cary Fowler, a scientist, conservationist and biodiversity advocate. Though there are more than 1,700 genebanks around the world that keep collections of seeds, they are all vulnerable to war, natural disasters, equipment malfunctions and other problems. In 2003, Fowler started to envision a backup storage facility where all of the world's seeds could be stored as safely as possible.

In 2008, Fowler's idea was realized and the Global Seed Vault was built, carved nearly 500 feet (152 meters) into the side of a mountain. In 2015, the Syrian war brought the first withdrawal from the seed vault. The seeds replaced those damaged in a gene bank (a facility that stores genetic material) near the war-torn Syrian city of Aleppo. In 2016, Fowler released a book on the vault called "Seeds on Ice: Svalbard and the Global Seed Vault."

Location

The Svalbard Global Seed Bank is located in Svalbard in a Norwegian archipelago (an area of ocean containing many islands) in the Arctic Ocean. Svalbard is found north of mainland Europe, halfway between continental Norway and the North Pole, according to the Norwegian Ministry of Agriculture and Food. 

"None of these reasons for locating the facility in Norway would have sufficed had it not been for the fact that Svalbard offers almost perfect conditions: it is remote and thus safer than other possible locations and it is naturally cold. We wanted to have a facility that would stay naturally frozen without the aid of mechanical freezing equipment. Inside the mountain in the permafrost, we get steady below-freezing temperatures. We mechanically lower the temperature further to about minus 18 C [0 F], but this is much easier to accomplish when you start at -5 C [23 F] rather than above freezing."

The site is also located in an area that is high up to prevent flooding; it is geologically stable and the area has low humidity. It is also the farthest north that scheduled airline flights go, making it very remote. If the electricity goes out or the refrigeration fails, the seeds will also still stay cold due to their location.

Preservation

In addition to keeping the seeds at 0 F, the seeds are sealed in three-ply foil packages and then sealed inside boxes. These boxes are placed on shelves inside the vault where temperature and moisture levels are closely monitored. This process helps keep the metabolic activity in the seeds low, keeping them viable for long periods of time.

The vault's purpose

Though the vault is thought of as a "doomsday vault" that will be the source of seeds for the world after a worldwide disaster, that isn't really true. 

"The seeds are not meant for distribution to farmers or gardeners," said Fowler. "Their value and utility lies in their being a genetic resource in plant breeding. So they are ultimately intended to serve plant breeders and other scientists who are involved in developing new crop varieties for farmers. Think of the seeds as a collection of traits, or even more broadly as a collection of options our crops will have in the future, options such as disease and pest resistance, drought and heat tolerance, better nutrition, etc." 

The vault, and other vaults around the world, can be a way of preserving historical species of plants, as well. According to National Geographic, an estimated 90 percent of historic fruit and vegetable varieties in the United States have disappeared. The seed vault can protect these seeds for future generations.

The Global Seed Vault is specifically meant, though, to be an aid to other banks.

"The seeds in the Seed Vault are duplicate copies of collections held in national and other seedbanks around the world," said Fowler. "If something happens to one of those facilities and if their seed samples are destroyed, then there is a backup copy in the Seed Vault. In the past the loss of a variety meant extinction for that variety and any unique trait it might have contained. Today, fires, floods, natural disaster, war, human error, accidents, funding cuts — none of these need cause the extinction of a crop variety. If that variety is in the Seed Vault, it's as safe as it can be."

Capacity

The Global Seed Vault can hold massive amounts of seeds. It is built to store a whopping 4.5 million varieties of crops, with each variety containing around 500 seeds. That equals a maximum of 2.5 billion seeds that can be stored in the Vault, according to Global Crop Diversity Trust, an international group that works in conjunction with the Norway government to manage the seeds in the vault. The vault currently holds more than 860,000 seed samples as of this writing. These seeds were donated by almost every country in the world, so there is a massive variety of seeds represented in the Global Seed Vault.

"Even though I have worked in this field for almost 40 years, I guess the biggest surprise was the breadth of diversity that came in from seedbanks around the world," said Fowler. "I expected a lot of rice and wheat (we have more than 150,000 distinct varieties of each). What I didn't expect to see were seeds of so many crops totally unfamiliar to me. When I print out a list of the crops represented in the Vault, it runs about 55 pages, single-spaced. Rice and wheat occupy two lines. I confess that I didn't know anything about 'cheesytoes,' or 'Asian pigeonwings' or 'zombie pea,' but we have all of these and much more."

Donations and seed retrieval 

The Global Seed Vault has a few rules about donations and seed retrieval. First, they only take donations that are part of the Multilateral System, which is part of an international treaty on food resources, or seeds that have originated in the country of the depositor. 

The Multilateral System is a provision of the International Treaty on Plant Genetic Resources for Food and Agriculture, which governs how plant genetics are shared. The treaty ensures that countries can freely share the genetic information of 64 crops that account for 80 percent of all human consumption through seed banks, according to the Food and Agriculture Organization of the United Nations. Those who use the information and find new information must agree to share the information or pay a percentage of money they receive because of their research into a common fund. 

The Global Seed Vault doesn't own or govern the seeds within it. Any seeds donated are still owned by those that donated. This means that only the people who donated can have access to those seeds or allow others to borrow them.  

Additional resources

• National Geographic: Pictures — "Doomsday" Seed Vault Safeguards Our Food Supply
• World Conservation Union: Explanatory Guide to the International Treaty on Plant Genetic Resources for Food and Agriculture
• Crop Trust: Interactive Visit to the Global Seed Vault

Marlene Cimons is a Washington, D.C. based freelance writer who specializes in science, health and the environment. Her work frequently appears in, among other outlets, The Washington Post, Microbe Magazine, and Climate Progress. She also writes for Climate Nexus, a nonprofit that aims to tell the climate story in innovative ways that raise awareness of, dispel misinformation about and showcase solutions to climate change and energy issues in the United States. She contributed this article to Live Science's Expert Voices: Op-Ed & Insights.

As prolonged drought and extreme temperatures have taken their terrible toll on food crops in recent years, nations have tended to focus on regional episodes, such as a single drought-afflicted state or region. Now, scientists have assessed the global scale of food crop disasters for the first time — and the news is not good.

In a new study, researchers from Canada and the United Kingdom estimate that cereal harvests — including rice, wheat and maize — decreased by an average of 9 to10 percent during droughts and heat waves between 1964 and 2007, with the worst effects seen in North America, Europe, and Australia and its neighboring islands. Furthermore, the impact has grown larger in recent years. With climate change likely to exacerbate extreme weather and make it more common in the future, the study is perhaps the most comprehensive examination yet of the historic impact of extreme weather on global crop production. 

Fading food supplies

The researchers' work builds on an accumulating body of research and reports that consistently warn of the devastating effects extreme weather is having on agriculture. And the effects will continue, with consequences including drastic food shortages, experts say. Studies from Bangladesh, Ethiopia and Niger have shown that children have increased wasting and stunting rates after a flood or drought, according to the United Nations World Food Programme. For example, children in Niger born during a drought are more than twice as likely to be malnourished between the ages of 1 and 2. Moreover, the U.N. food program estimates that hunger and child malnutrition could increase by as much as 20 percent by 2050 as a result of climate change. [Food Prices, Global Hunger to Skyrocket by 2030, Oxfam Warns]

Extreme weather causes crop production losses, but until now, scientists "did not know exactly how much global production was lost to extreme weather events and how they varied by different regions of the world," said Navin Ramankutty, a professor of global food security and sustainability at the Liu Institute for Global Issues at the University of British Columbia, and one of the study authors.

The researchers, whose work appears in a recent issue of the journal Nature, also include Corey Lesk, of The Earth Institute at Columbia University and the NASA Goddard Institute for Space Studies in Manhattan, and Pedram Rowhani, a lecturer in geography and international development at the University of Sussex.

Keeping food on the table

While shortages don't necessarily spell extinction for your morning bowl of cornflakes, cereal could end up costing you a lot more. More important, because cereal grains are a staple of the global diet, the situation could have a catastrophic impact on farmers and the world's hungry. 

"I think most Americans are relatively able to withstand food price shocks," said Lesk, first author of the study. "But the most vulnerable people, both in the United States and elsewhere, can be forced into dangerous situations by these disasters. I think it's important for Americans to keep these people in mind, especially because these disasters are likely to become more common in the future."

Those crises could mean lost income for American commercial farmers, as well as food shortages for poorer subsistence farmers, who rely on their crops to feed themselves and their families, Lesk said. 

Food insecurity still persists in the United States; an estimated 14 percent of American households (17.4 million), were food "insecure" in 2014, meaning they had difficulty at some point during the year providing enough food for their families due to a lack of resources, according to a recent report from the U.S. Department of Agriculture. 

The findings from the new research may help guide agricultural priorities in international disaster risk reduction, as well as adaptation efforts. "We can avoid a worsening food-security situation if we invest in adapting our crops to these extremes immediately, and especially if we step up and make solid commitments to avoid further climate change," Lesk said.

Harvesting the data

Lesk and his colleagues analyzed national agricultural-production data from the United Nations' Food and Agriculture Organization for 16 cereals in 177 countries. They also examined 2,800 international weather disasters from 1964 to 2007. 

They found that cereal harvests decreased due to both droughts and extreme heat, and production levels in North America, Europe and Australasia dropped by an average of 19.9 percent from droughts alone — roughly double the global average.

Moreover, the average impact of recent droughts — those between 1985 and 2007 — was a 13.7 percent loss, which is 7 percent greater than the 6.7 percent impact during droughts that occurred earlier, between 1964 and 1984. The reasons for this are not clear.

"We found that the average impact of drought disasters on crops has gotten worse," Lesk said. "But it is still debated whether droughts themselves have gotten more severe, so another explanation could be that crops have gotten more susceptible to drought over the decades. That could mean, speculatively, that we're already on the wrong path with regard to adapting our crops to a changing climate. 

"The thinking is that, if crop responses to drought have gotten bigger, but there is no clear signal that the droughts have gotten worse, then that supports the alternative explanation that crops themselves have gotten more sensitive," he added. "And if they have gotten more sensitive already, that bodes ill for future crop performance in a world of worse droughts."

Crop failure

The researchers found that production losses due to droughts were associated with a reduction in both harvested area and yields, whereas extreme heat mainly decreased yields.

Harvested area refers to the planted cropland area that is harvested in a given year. 

"It takes time, energy and money to harvest crops from a field, and if crops are severely enough damaged, then farmers may choose not to harvest at all," Lesk said. "You could call this a 'total crop failure,' and it shows up in the data as a drop in harvested area. Yield is the mass of grain harvest per unit area harvested — in other words, the productivity of the crops on an area basis. If a crop fails completely and is not harvested, then it doesn't end up in the yield calculations, so you have to consider both metrics to get a full picture."

The scientists concluded that droughts caused partial and total damage to crops, resulting in drops in both yield and harvested area. Heat waves, in contrast, only resulted in yield declines. "Droughts can cause more complete crop failures, possibly because they can last so long and damage crops so severely that farmers don't bother harvesting," Lesk said. "Another aspect is that longer droughts might discourage planting altogether, possibly because farmers have run out of water for irrigation or money for seeds." 

The scientists did not specifically analyze any price or trade effects, but they have "come up with a quick, rough estimate for the 9 to 10 percent in annual dollar terms," Lesk said. "About $10 billion worth of crops per year, globally, has been lost to drought and heat waves," Lesk said.

The researchers did not find any impacts from floods or extreme cold. Also, in one optimistic result, their analysis found that extreme weather events had no lasting impact on agricultural production in the years that followed the disasters. 

Nevertheless, the work provides another compelling argument "to start scaling up the myriad climate change mitigation strategies that already exist — green subsidies and investment, carbon taxes and markets, and especially ending fossil fuel subsidies," Lesk said. "Climate change poses a colossal economic risk to the world — tens to hundreds of trillions of dollars in damage, by some estimates. Spending now to avoid it is truly an excellent investment."

Follow all of the Expert Voices issues and debates — and become part of the discussion — on Facebook, Twitter and Google+. The views expressed are those of the author and do not necessarily reflect the views of the publisher. This version of the article was originally published on Live Science.

Some bacteria have finally breached the last wall of humans' antibiotic stronghold, according to a new study from China. In the study, researchers found a gene in one strain of Escherichia coli (E. coli) that protects these bacteria against one of the antibiotics considered to be a last resort.

Moreover, this gene is easily transferred among microbial species, raising the possibility of multiple epidemics that doctors would be unable to treat.

The results are "extremely worrying," study author Jian-Hua Liu, a professor at South China Agricultural University in Guangzhou, said in a statement. When bacteria become resistant to even the last-resort antibiotics and can share that resistance with other types of bacteria, that leaves the human population extremely vulnerable to a range of infections that would be unstoppable, he said. [6 Superbugs to Watch Out For]

In the study, the researchers found the gene, called mcr-1, in samples of E. coli that were taken from pigs, pork products and infected people. The gene protects the bacteria against an antibiotic called colistin.

Mcr-1 was most common in the samples taken from animals, suggesting that it originated in livestock, the researchers said. In China, colistin is widely administered to livestock.

Animals that are raised for people to eat are routinely given antibiotics to protect the livestock against infection, and to stimulate their growth. But the constant presence of antibiotics in the livestock diet helps drive the increasing numbers of antibiotic resistant bacteria today, researchers say.

'Old reliable' antibiotic

Colistin isn't a recent addition to the drug arsenal. It was discovered in 1947, and was used widely through the 1960s, but the drug had toxic effects on the kidneys and nervous system, said Dr. William Schaffner, an infectious disease specialist and professor of preventive medicine at Vanderbilt University Medical Center in Nashville, Tennessee.

Doctors mostly abandoned colistin after newer and safer antibiotics came along, said Schaffner, who was not involved in the new study.

But sitting on the shelf for decades is exactly what kept colistin viable in the battle against drug-resistant bacteria, Shaffner said. Because microbes had little exposure to colistin, they did not have much opportunity to evolve protection against it. As the list of effective antibiotics has shrunk, colistin has remained one of the last reliable lines of defense against bacterial infection.

That is, until now. In the new study, the researchers found the gene for colistin resistance in bacterial structures called plasmids, which are small circles of DNA that are easily passed from one bacterium to another, and even between different bacterial species.

Researchers have long known that the use of antibiotics, in both agriculture and in medicine, has encouraged bacteria to do what they've excelled at for more than 3 billion years: evolve and survive.

"Our ability to make new antibiotics will always be outpaced by the ability of bacteria to devise resistance mechanisms," said Dr. Amesh A. Adalja, an infectious disease specialist and senior associate at the University of Pittsburgh Medical Center's Center for Health Security. [7 Devastating Infectious Diseases]

"Facing an antibiotic winter"

Bacteria are very, very good at protecting themselves, said Adalja, who was not involved in the study. For billions of years, bacteria have been fine-tuning defenses against other microbes that could harm them. Since many antibiotics are derived from microorganisms, when doctors use these drugs against bacteria, "we're playing in their field," Adalja added, presenting them with an opponent that evolution has primed them to defeat.

The new drug-resistant bacteria have not been found outside of China, the investigators said. But the researchers warned there is a strong possibility this drug-resistance gene could spread, and they called for "very close internal monitoring and surveillance" of the gene, in both human and animal medicine, and for evaluating the continued use of colistin and related antibiotics.

"We are already facing an antibiotic winter that resembles the pre-antibiotic era," Schaffner warned. "We infectious-disease doctors are in the very uncomfortable position of having to try to treat an infection where the bacteria is resistant to so many antibiotics. In essence, we don't have any more bullets left in our gun," he said.

Right now, preventing bacterial infections with measures such as vaccinations and good hand hygiene are more vital then ever, Schaffner stressed. He noted that antibiotics are useful only against bacterial infections, and that taking antibiotics when they're not needed just gives bacteria another chance to beef up their drug-resistant defenses.

But the best hope for defeating infection-causing bacteria may require overhauling today's approach to fighting disease, to make people less dependent on treatments that bacteria are likely to defeat, Adalja told Live Science.

Although antibiotics may still be useful, doctors might be better served by diversifying their tactics, using more targeted therapies against bacteria, like "attack viruses" known as bacteriophages, or developing new preventative measures, he said.

"There's a whole host of approaches, these next-generation or novel therapies that move us beyond antibiotics," Adalja said.

The findings were published online Nov. 18 in the journal The Lancet Infectious Diseases.

Follow Mindy Weisberger on Twitter and Google+. Follow us @livescience, Facebook & Google+. Original article on LiveScience.

The ongoing civil war in Syria has led to the first-ever withdrawal from the Svalbard "doomsday" Global Seed Vault, a giant storage unit for plant seeds that's tucked into the side of a frigid mountain in Norway.

Established in 2008, the seed vault serves as a safe haven for the world's vast variety of edible plant seeds. In the event of a nuclear war or catastrophic natural disaster, the vault keeps "backup" seeds frozen and safe until they can be reclaimed.

So far, seeds have only gone into the vault for storage, not come out. But this week, researchers in the Middle East asked to withdraw seeds that they had previously deposited into the seed bank, according to the Global Crop Diversity Trust, the international organization that manages the doomsday vault in cooperation with the Norwegian government. The withdrawn seeds were needed to replace plant material stored in a gene bank (a facility that stores genetic material) near the war-torn city of Aleppo in Syria. [7 Perfect Survival Foods]

The reclaimed seeds included varieties of wheat, barley, grass pea and other important food crops that are maintained by the International Center for Agricultural Research in the Dry Areas (ICARDA), a nonprofit research organization that aims to improve the livelihoods of people in resource-poor areas across the Near East and North Africa. After the war damaged its facility in Syria, ICARDA moved its headquarters to the Lebanese capital of Beirut.

While it may sound like bad news that seeds have been removed from the so-called doomsday vault, the withdrawal actually serves as proof that such a vault is necessary, Brian Lainoff, a spokesman for the Crop Trust, told The WorldPost.

Constructed as a sort of last-ditch effort at protecting plants from extinction, the seed bank is meant to serve as a backup for gene banks like ICARDA, Lainoff said.

"If something were to happen to one of those collections around the world, they can always come back to the seed vault and retrieve what might have been lost," Lainoff told The WorldPost.

Seeds stored in the Svalbard vault, which is built right into a sandstone mountain and covered in a thick layer of permafrost, are kept at an icy minus 0.4 degrees Fahrenheit (minus 18 degrees Celsius). Should the power at the facility fail for any reason, the seeds will likely stay frozen thanks to the permafrost that covers the vault.

And there's very little chance that any ne'er-do-wells could make off with the world's most precious supply of seeds. The vault is secured by four sets of locked doors, according to the Crop Trust. There are also the Svalbard archipelago's most notorious security guards to consider. Located about 800 miles (1,300 kilometers) from the North Pole, the area surrounding the vault is extremely remote, secluded and home to a number of polar bears.

Right now, the vault holds just less than 865,000 seed samples from all over the world, but it's capable of holding many more. In total, the vault can handle about 2.5 billion seeds (or about 500 seeds each from about 4.5 million varieties of crops).

You can learn more about the Svalbard Global Seed Vault and take a virtual tour of the underground facility by visiting the Crop Trust website.

Follow Elizabeth Palermo @techEpalermo. Follow Live Science @livescience, Facebook & Google+. Original article on Live Science.

Although genetically modified organisms (GMOs) don't appear by themselves to have ill effects on human health, the herbicides used on these crops could be an overlooked health threat, some researchers say in a controversial new opinion piece.

People have been manipulating genes in plants for centuries, but arguing that this means GMOs are safe "misses the point that GM crops are now the agricultural products most heavily treated with herbicides, and that two of these herbicides may pose risks of cancer," Dr. Philip Landrigan, a professor of preventive medicine at Mount Sinai School of Medicine in New York, and Charles Benbrook, a crop and soil scientist at Washington State University, wrote in an opinion article published in the Aug. 20 issue of the New England Journal of Medicine (NEJM).

Most of the corn and soybeans grown in the United States are genetically engineered. This means that products made from these crops are also GM foods, everything from soda to tofu.

Many of today's GM crops have been engineered to be resistant to weed killers, and this has led to an overreliance on these chemicals, Landriganand Benbrooksaid. The authors argued that because some studies have linked cancer risk to the herbicides used on GM crops — in particular, a widely used herbicide called glyphosate (sold under the brand name Roundup) — the United States should reconsider creating labeling requirements for GM foods.

Labeling is essential for "assessing effects of chemical herbicides applied to GM crops," the two researchers wrote. 

However, other experts disagreed with the opinion and said that the majority of studies have failed to find a link between glyphosate and cancer, and that this herbicide is much safer than chemicals used on crops in the past. "The whole [NEJM] article is dubious," said Kent Bradford, a professor of plant science at the University of California, Davis. Bradford noted that one of the authors of the new article (Benbrook) has received funding from and served on the board of the Organic Center, a nonprofit organization that says it brings together "evidence-based science on the health and environmental benefits of organic food and farming."

Landrigan and Benbrook wrote that the emergence of weeds that are resistant to herbicides led farmers to increase their use of these chemicals on crops. And in 2014, the Environmental Protection Agency (EPA) approved the use of a new weed killer called Enlist Duo. This chemical contains glyphosate as well as an herbicide called 2,4-Dichlorophenoxyacetic acid (2,4-D), a component of Agent Orange used in the Vietnam War. (A different component of Agent Orange, called dioxin, has already been linked to cancer.) [7 Medical Myths Even Doctors Believe]

The EPA estimates that the approval of Enlist Duo will result in a 3- to 7-fold increase in the use of 2,4-D in the United States, according to the NEJM article.

Landrigan and Benbrook argue that this approval was based on flawed studies, which were commissioned by the manufacturer and did not examine whether the substance could have effects on people's hormones, or the regulation of human genes.

In addition, earlier this year, the International Agency for Research on Cancer classified glyphosate as a "probable human carcinogen" and 2,4-D as a "possible human carcinogen," the NEJM article says.

This decision on glyphosate was based mostly on research done in animals, with studies finding links between glyphosate and tumors in rodents. Some studies have also suggested that people who work with glyphosate may be at higher risk for non-Hodgkin lymphoma. The decision on 2,4-D was based mostly on studies done in lab dishes and in animals; this research found that 2,4-D could cause oxidative stress, which is thought to increase cancer risk by damaging DNA.

"These developments suggest that GM foods and the herbicides applied to them may pose hazards to human health that were not examined in previous assessments," Landrigana nd Benbrook said.

However, Bradford said that most review studies, including studies from the European Union and the U.S. EPA, have concluded that glyphosatedoes not pose a risk of cancer. "Glyphosate is well known to be a very nontoxic compound," Bradford said.

Bradford also noted that herbicides are used on all crops, not just those that are genetically modified. For example, 2,4-D is used on U.S. wheat crops, which are not genetically modified, he said.

What's more, studies from the U.S. Department of Agriculture have found that herbicides that were used in the past were up to 16 times more damaging to the environment than is glyphosate, Bradford said. "We should be happy that we were able to move to a much less environmentally impacting herbicide," he said.

Margaret Smith, a professor of plant breeding and genetics at Cornell University in New York state, said she agreed with the authors of the NEJM article that use of GM crops resistant to herbicides, and use of glyphosate, have gone up in recent years. "There's no question" that there's been an increase in these factors, Smith said.

But Smith also said that glyphosate has a relatively benign impact on the environment, and that its use replaced more environmentally hazardous products. In addition, the increased use of herbicides on GM crops has meant that farmers don't need to plow their fields as often as a means of killing weeds. This reduction in plowing has environmental benefits, because plowing increases soil erosion and runoff, Smith said.

However, the downside of herbicide use on GM crops is that when agriculturalists use the same pest management tactic for years, they start to see pests (such as weeds) that are resistant.

"As the use of Roundup has become broader and more common, we now see more evolution of weeds that are less susceptible to it," Smith said. "That's a very predictable thing."

The authors wrote that they believe that the EPA should delay the implementation of Enlist Duo until more independent studies on the herbicide are completed.

Follow Rachael Rettner @RachaelRettner. Follow Live Science @livescience, Facebook & Google+. Original article on Live Science.

All farmers on the ground know their land as well as their own wrinkled hands, but totaling up all the world's cropland is a difficult task. Yet the competition for land among developers, growers and other parties makes getting an accurate count of the world's arable acres especially important as the planet's population grows.

Two new maps released Friday (Jan. 16) considerably improve estimates of the amount of land farmed in the world — one map reveals the world's agricultural lands to a resolution of 1 kilometer, and the other  provides the first look at the sizes of the fields being used for agriculture, the researchers said. Earlier studies estimated that the world's cropland may cover an area between 1.22 billion and 1.71 billion hectares, a range that varies by more than 40 percent.

"The field-size map is really unique — no such global product currently exists," study co-author Linda See, a researcher at the International Institute for Applied Systems Analysis in Austria, said in a statement.

The researchers built the cropland database by combining information from several sources, such as satellite images, regional maps, video and geotagged photos, which were shared with them by groups around the world. Combining all that information would be an almost-impossible task for a handful of scientists to take on, so the team turned the project into a crowdsourced, online game. Volunteers logged into "Cropland Capture" on a computer or a phone and determined whether an image contained cropland or not. Participants were entered into weekly prize drawings. [Farming in America (Infographic)]

The new global cropland map shows the extent of land dedicated to farming in 2005, and the field-size map illustrates different approaches to farming. It turns out that medium and large fields dominate in North America, central South America, Europe and Australia, while small fields pepper the farming regions in Africa, India, Southeast Asia and China.

The researchers said they hope the global cropland map will become a reference map for climate modelers, as well as agencies that monitor and report on agricultural development worldwide. The field-size map is more a rough first step in looking at the world's fields, but offers a new way to monitor global agriculture, the scientists said. For instance, a growth in field sizes in a certain region could reflect a shift there toward development and mechanization.

"Current sources of information on cropland extent are not accurate enough for most applications," study lead author Steffen Fritz said in the statement. "The global cropland map is a low-cost solution to fill this need."

Both maps are free to download from the "Cropland Capture" game host website, called Geo-Wiki, with online registration. The researchers are now producing a new cropland map for 2010, and updating the field-size map, they said.

The maps were also published in the journal Global Changes Biology.

Follow Becky Oskin @beckyoskin. Follow LiveScience @livescience, Facebook & Google+. Originally published on Live Science.