Caves pockmark the world, extending deep into the bowels of Earth. Many caves are record holders, including one in Kentucky that's the longest known cave system, another in Vietnam that's the largest cave, and one in Mexico that holds the title for the longest underwater cave. But caves are known for being dark abysses, so which is the deepest cave on Earth? And which strange animals live at their deepest depths?

There's no clear winner, Live Science found. Instead, there are two caves that alternate as the record holders for the deepest cave on our planet: Veryovkina and Krubera-Voronya (also spelled Voronja), limestone caves in Abkhazia, an autonomous republic in the Republic of Georgia.

Both of these caves are more than 6,560 feet (2,000 meters, or 1.2 miles) deep, and they sit on the same remote mountain range, known as the Gagra Range. Explorers and scientists frequently update each cave's measurements.

According to a list of the world's deepest caves maintained by geologist Paul Burger, a regional hydrologist in Alaska for the National Park Service, Veryovkina is currently in the lead, with a depth of 7,257 feet (2,212 m, or 1.37 miles). Krubera is close behind, at 7,215 feet (2,199 m, or 1.37 miles).

"Both caves are frequently reported with vertical errors of plus/minus tens of feet so first and second place can vary depending on how those data are interpreted," Burger, who is also the author of the book "Cave Exploring: The Definitive Guide to Caving Technique, Safety, Gear, and Trip Leadership" (Myotis Publishing, 2022), told Live Science in an email.

The two caves are located in the Arabika Massif, a glacially eroded karst in the Caucasus. Karst is a type of landscape formed by soluble rocks like marble, gypsum and, in this case, limestone from the Late Jurassic and Early Cretaceous periods, or from about 163.5 million to 100.5 million years ago. Over time, the limestone lays down in layers, and then it gets compressed by tectonic forces and turns into vertical walls of rock, Hazel Barton, a microbiologist and geologist at the University of Alabama, told Live Science.

"If you can imagine all those layers, you've got a BLT sandwich," she said. If you turn that BLT vertically, "when the water goes in, it's always going to look for the easiest way down." The water travels through cracks, eventually hitting the water table. "It's basically a massive bathtub down there," Barton said. Once the water hits the water table, it becomes groundwater and circulates in subterranean streams and rivers.

The reason this region has so many deep caves has to do with mountain building, Barton said "The limestone beds have been tilted near vertically, so the easiest route for the water is just straight down. You also have a large plateau that can collect the water, which helps push it one way or another."

Life in the caves

These caves aren't cozy. They're extremely dark, wet and cold environments. Temperatures inside caves in this region average 35 to 37 degrees Fahrenheit (2 to 3 degrees Celsius) throughout the year, said Ana Sofia Reboleira, a subterranean ecologist at the University of Lisbon in Portugal.

These conditions are harsh, and any organisms living there must adapt in order to survive. The deeper you go into caves, the more limited the nutrients become there. Animals need to slow their metabolism so they can go long stretches without eating, which allows them to live longer, Reboleira said. Their features are also adapted to life underground; most animals living at such depths lack pigment and eyes. They also have long appendages, hair and antennae to help them move in the darkness and sense air vibrations inside the cave.

One of these deep-dwelling species is a type of wingless insect known as a springtail, which Reboleira and her colleagues discovered on a 2010 expedition to Krubera at about 6,500 feet (1,980 m, or 1.2 miles) below the surface. The hexapod, named Plutomurus ortobalaganensis, feeds on fungi and decomposing organic matter. Sixteen years later, it still holds the record for the deepest known land animal.

Subterranean microbes have also evolved mechanisms to survive deep underground. At extreme depths, these microbes rely on chemolithoautotrophy, a metabolic process that enables them to gain energy by oxidizing the bedrock and turning it into food, Barton explained.

By understanding these subterranean environments, scientists can learn more about what's happening underneath our feet. "Caves are windows to the vast dimension of the underworld," Reboleira said.

Caves are ultimately part of a system that is fundamental for all ecosystems on our planet. They provide water purification by filtering water their their many layers, play an important role in nutrient cycling, and sustain the carbon cycle by storing carbon in stone and hosting organisms that turn carbon dioxide into organic matter.

"Subterranean ecosystems are absolutely vital and strategic for ensuring life on Earth," Reboleira said.

How much do you know about our blue planet? Test your terran knowledge with our Earth quiz!

While exploring a cave in central Texas, scientists unearthed a long-lost ice-age ecosystem, including the remains of a giant tortoise and a lion-size armadillo relative, among a trove of fossils in an underground stream.

In a study published March 19 in the journal Quaternary Research, researchers say the cave may preserve the remains of animals that lived during a relatively warm period of the last ice age. If the findings are validated, the site would offer a rare look at an animal community that was missing from central Texas' fossil record.

"It blew my mind," lead author John Moretti, a vertebrate paleontologist in the University of Texas at Austin's Jackson School of Geosciences, told Live Science. "Just the abundance of fossils and the animals those fossils represent were really exciting."

Moretti and John Young, a local caver, were exploring Bender's Cave, near San Antonio, in 2023, when they came across the fossils. The cave is difficult to access and has a subterranean stream running through it, so it had largely been ignored by paleontologists. However, they suspected fossils were present, as amateur cavers had previously brought in their finds, Moretti said.

It was Moretti and Young who found the ice-age fossils simply lying in the mud.

"We have bags attached to our waists, and we're picking up fossils as we go," Moretti said. Over six trips between 2023 and 2024, Moretti and Young discovered fossils from 21 areas in the cave. Among the finds were a claw from a giant sloth (Megalonyx jeffersonii), mammoth teeth, and bones of camelids (Camelops), the long-legged ancient relatives of modern day llamas.

But what really intrigued them was the discovery of fossils of two ice-age beasts: a pampathere (Holmesina septentrionalis), a giant armadillo relative that lived during the middle to late Pleistocene (781,000 to 126,000 years ago) ; and an extinct genus of giant tortoise (Hesperotestudo).

The discovery of these two fossilized animals puzzled Moretti and Young because these ice-age giants were not known to have lived in this area. For more than a century, researchers have studied ice-age fossil sites in central Texas and built a picture of the region during that time as a dry grassland dominated by grazing animals. According to Moretti, this climate would not have been suitable for the tortoise or the pampathere.

Moretti and Young suggested that the animals' remains washed into the cave system from the surface through sinkholes during floods and then settled on the streambed. If this is the case, the animals may have lived during a warmer interglacial period, roughly 100,000 years ago, when temperatures rose and animals that favored milder conditions moved into the region, the researchers proposed.

Moretti said they have not been able to accurately date the bones because the collagen proteins often used as the biomarker in fossils were completely eroded by the mineral-rich water. This water also contaminated many of the fossils, as the bones absorbed carbon and other minerals after being deposited. This means a test may measure this contamination rather than the fossils' true ages.

To overcome this challenge, the team is now trying to date the calcite crusts that formed on the bones after they entered the cave. Although these results won't provide exact dates for the fossils, they can set a minimum age for when they were deposited. With these dates, the researchers hope to narrow down whether the cave fossils represent a warmer interglacial chapter of Texas' history.

"We still don't know everything about the natural world," Moretti said. "There's still a lot to discover out there."

Think you know all about the ice age? Test your smarts with our mammoth quiz!

Two Neanderthals present at the same cave site 10 millennia apart were distant relatives, a tiny 110,000-year-old bone fragment from the Altai Mountains in Siberia reveals. The fragment has also produced the fourth full genome of a Neanderthal to date, shedding light on how small and isolated Neanderthals were long before they disappeared around 40,000 years ago.

Researchers found the bone fragment in Denisova Cave, which both Neanderthals and Denisovans lived in off and on for nearly 300,000 years. In a study published Monday (March 23) in the journal PNAS, the researchers compared the genome of the 110,000-year-old Neanderthal male (called D17) with three other complete Neanderthal genomes to better understand Neanderthals' population structure.

The researchers compared the genome of D17 with the genome of a female Neanderthal (called D5) dated to 120,000 years ago from the same cave. They found that, while D5 was not a direct ancestor of D17, the two Neanderthals belonged to closely related lineages connected by a common ancestor. This distant biological relationship suggests Neanderthals had a long-term presence in the Altai region, the researchers said.

"But it is likely that Denisova Cave was part of a broader landscape used repeatedly by these Neanderthal populations over time, rather than a site occupied by a single, continuous group," study first author Diyendo Massilani, a genetics professor at the Yale School of Medicine, told Live Science in an email.

The study results also revealed that Neanderthals in the Altai region lived in very small and highly isolated populations of 50 or fewer people, as shown by stronger genetic markers of inbreeding. Specifically, researchers found that the individuals they analyzed had large sections of identical DNA, an indication that their parents were very closely related — as close as first cousins, for example.

The new research complements previous studies that showed Neanderthals lived in smaller and more isolated groups than our own species did. A 2022 study indicated that one Altai Neanderthal community numbered around 20 individuals, while another study provided evidence of a group being isolated for roughly 50,000 years. Many researchers have pointed to inbreeding and isolation as causes for Neanderthals' disappearance around 40,000 years ago. But the latest results suggest that Neanderthals also survived for long periods under extreme conditions of isolation and small population size.

Massiliani and colleagues also discovered that Altai Neanderthals were very different from later European Neanderthals. In their genetic analysis, the researchers found that Altai Neanderthal D17 was more closely related to D5 than either of them was to Neanderthals in Europe or to later populations in the Altai region. This suggests that Neanderthal populations from eastern and western Eurasia became genetically different from one another in a relatively short time frame and within a fairly small geographic area.

"Even though the individuals from which we have genomes were separated for only about 50,000 years on average, they reached levels of difference similar to what we see today between some of the most distinct human populations, like people from Central Africa and Papua New Guinea that separated about 300,000 years ago," Massilani said.

Likely because they were small and isolated, Neanderthal populations became genetically distinct from one another much more quickly, Massilani said. This may have been because in small, isolated groups, a process called genetic drift can cause random genetic changes to become more common over time.

"We already knew that Neanderthals were not a single, homogeneous population spread across Eurasia, but a patchwork of groups shaped by complex demographic processes, including divergence, migration, local extinctions and replacements," he said. "What is striking in our results is just how differentiated these populations could become."

The high amount of genetic separation and differences between groups may have limited Neanderthals' ability to adapt to environmental changes, Massilani said.

The study provides new details about how Neanderthal populations were structured, one expert said.

"To have two sequenced Neanderthals in such a close geographic place does bring new and more fine-grained insight" into their population, Léo Planche, a population geneticist at Paris-Saclay University's Interdisciplinary Laboratory for Digital Sciences who was not involved in the study, told Live Science in an email. "We start to have enough Neanderthal genomes to actually have some claim about their population structure. Populations are groups of individuals, so the more data the better."

Editor's note: This article was updated on March 27, 2026 to note that the vast majority of Neanderthals went extinct 40,000 years ago, not 34,000 years ago as was previously stated.

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

The oldest known sewn clothing in the world may be pieces of animal hide that Indigenous people stitched together with plant and animal cords and then left in an Oregon cave around 12,000 years ago, during the last ice age, a new study finds.

Although its exact use is unknown, the sewn hide is "quite possibly a fragment of clothing or footwear," which would represent the only known item of clothing recovered from the Pleistocene to date, the researchers wrote in the study, which was published Feb. 4 in the journal Science Advances.

An amateur archaeologist discovered the sewn hides in 1958, but the new study is the first to date the artifacts. In their paper, the team determined that 55 pieces of crafted animal and plant materials previously unearthed in two Oregon caves — including sewn hide, cords and twine — stemmed from the Younger Dryas, a period of sudden cooling that occurred from about 12,900 to 11,700 years ago.

The discovery provides clear evidence that Indigenous people in North America shielded themselves from the worst of the cold by using complex technology made from perishable materials. Sewing pieces of hide together allowed for tight-fitting clothing, which would have provided more warmth than simple, loose-fitting draped hide clothes.

"We already knew they did, we just had to assume and guess what they were like," study lead author Richard Rosencrance, a doctoral researcher in anthropology at the University of Nevada, Reno, told Live Science in an email. "They were accomplished and serious sewists during the Ice Age."

Clothes, along with other technologies required to keep people warm, were essential for permanent residence in northern latitudes, including areas of North America. But exactly when humans began to wear clothes is unknown, and the perishable nature of the materials means they are rarely found.

To date, there are only four sites — all in Oregon and Nevada — where non-bone animal and plant technology from the Late Pleistocene has been discovered in the Western Hemisphere. (The Late Pleistocene spanned 126,000 to 11,700 years ago and includes the last ice age.)

Archaeologists previously discovered two of the largest collections of Late Pleistocene perishable tools in the world in Cougar Mountain Cave and the Paisley Caves in Oregon, according to the new study. These artifacts included 37 fiber cords, baskets and knots; 15 wooden implements; and three sewn hides.

Rosencrance and his team used radiocarbon dating to determine the ages of these artifacts and confirmed that all of them date to the Younger Dryas. The cords were braided using three strands and were made using sagebrush, dogbane, juniper and bitterbrush fibers. Because the cords varied from 0.13 to 1 inch (0.33 to 2.5 centimeters) wide, they were probably used for a range of purposes, the researchers wrote in the study.

The three pieces of animal hide had been processed and dehaired, with cord made from a combination of plant fiber and animal hair sewn into the sides. The sewn hide dates to between 12,676 and 11,956 years ago, and an analysis of the chemical makeup of the animal hides revealed they came from North American elk (Cervus canadensis). (The oldest known shoes in the world are also from a cave in Oregon, and they date to about 10,400 years ago.)

The authors of the new study also examined 14 eyed and three eyeless bone needles that had previously been discovered at Cougar Mountain Cave and the Paisley Caves, as well as the nearby Connley Caves and Tule Lake Rockshelter. In addition, they looked at four potential ornamental items uncovered in the Connley Caves, including a porcupine tooth with a hole drilled into the top and lines scratched onto the surface.

"The abundance of bone needles and the presence of adornment items and very fine-eyed needles suggest that clothing was more than a utilitarian survival strategy but also an avenue of expression and identity," the authors wrote. "This evidence pushes beyond conventional assumptions to confirm that Pleistocene peoples in the Americas used clothing as both survival technology and social practice."

Eyed bone needles disappeared from the archaeological record in Oregon after around 11,700 years ago, Rosencrance said, which suggests that tight-fitting clothing became less important as the climate warmed.

Editor's Note: This story was updated on March 5 at 9:29 a.m. ET to correct the date range of the sewn hide. The radiocarbon dates were 12,600 to 11,880 before present (BP), calibrated to 1950, meaning the hide is 12,676 to 11,956 years old.

The last two decades have seen a revolution in scientists' ability to reconstruct the past. This has been made possible through technological advances in the way DNA is extracted from ancient bones and analyzed.

These advances have revealed that Neanderthals and modern humans interbred — something that wasn't previously thought to have happened. It has allowed researchers to disentangle the various migrations that shaped modern people. It has also allowed teams to sequence the genomes of extinct animals, such as the mammoth, and extinct agents of disease, such as defunct strains of plague.

While much of this work has been carried out by analyzing the physical remains of humans or animals, there is another way to obtain ancient DNA from the environment. Researchers can now extract and sequence DNA (determine the order of "letters" in the molecule) directly from cave sediments rather than relying on bones. This is transforming the field, known as paleogenetics.

Caves can preserve tens of thousands of years of genetic history, providing ideal archives for studying long-term human–ecosystem interactions. The deposits beneath our feet become biological time capsules.

It is something we are exploring here at the Geogenomic Archaeology Campus Tübingen (GACT) in Germany. Analyzing DNA from cave sediments allows us to reconstruct who lived in ice age Europe, how ecosystems changed and what role humans played. For example, did modern humans and Neanderthals overlap in the same caves? It's also possible to obtain genetic material from faeces left in caves. At the moment we are analyzing DNA from the droppings of a cave hyena that lived in Europe around 40,000 years ago.

The oldest sediment DNA discovered so far comes from Greenland and is 2 million years old.

Paleogenetics has come a long way since the first genome of an extinct animal, the quagga, a close relative of modern zebras, was sequenced in 1984. Over the past two decades, next-generation genetic sequencing machines, laboratory robotics and bioinformatics (the ability to analyze large, complex biological datasets) have turned ancient DNA from a fragile curiosity into a high-throughput scientific tool.

Today, sequencing machines can decode up to a hundred million times more DNA than their early predecessors. Where the first human genome took over a decade to complete, modern laboratories can now sequence hundreds of full human genomes in a single day.

In 2022, the Nobel prize in physiology or medicine was awarded to Svante Pääbo, a leading light in this field. It highlighted the global significance of this research. Ancient DNA now regularly makes headlines, from attempts to recreate mammoth-like elephants, to tracing hundreds of thousands of years of human presence in parts of the world. Crucially, advances in robotics and computing have allowed us to recover DNA from sediments as well as bones.

GACT is a growing research network based in Tübingen, Germany, where three institutions collaborate across disciplines to establish new methods for finding DNA in sediments. Archaeologists, geoscientists, bioinformaticians, microbiologists and ancient-DNA specialists combine their expertise to uncover insights that no single field could achieve alone —- a collaboration in which the whole genuinely becomes greater than the sum of its parts.

The network extends well beyond Germany. International partners enable fieldwork in archaeological cave sites and natural caves all over the world. This summer, for example, the team investigated cave sites in Serbia, collecting several hundred sediment samples for ancient DNA and related ecological analyses. Future work is planned in South Africa and the western United States to test the limits of ancient DNA preservation in sediments from different environments and time periods.

A needle in a haystack

Recovering DNA from sediments sounds simple: take a scoop, extract, sequence. In reality, it is far more complex. The molecules are scarce, degraded and fragmented, and mixed with modern contamination from cave visitors and wildlife. Detecting authentic ice age molecules relies on subtle chemical damage patterns to the DNA itself, ultra-clean laboratories, robotic extraction, and specialized bioinformatics. Every positive identification is a small triumph, revealing patterns invisible to conventional archaeology.

Much of GACT's work takes place in the caves of the Swabian Jura within Unesco World Heritage sites such as Hohle Fels, home to the world's oldest musical instruments and figurative art. Neanderthals and Homo sapiens left behind stone artifacts, bones, ivory and sediments that accumulated over tens of millennia. Caves are natural DNA archives, where stable conditions preserve fragile biomolecules, enabling researchers to build up a genetic history of ice age Europe.

One of the most exciting aspects of sediment DNA research is its ability to detect species long gone, even when no bones or artifacts remain. A particular focus lies on humans: who lived in the cave, and when? How modern humans and Neanderthals use the caves and, as mentioned, were they there at the same times? Did cave bears and humans compete for shelter and resources? And what might the microbes that lived alongside them reveal about the impact humans had on past ecosystems?

Sediment DNA also traces life outside the cave. Predators dragged prey into sheltered chambers, humans left waste behind. By following changes in human, animal and microbial DNA over time, researchers can examine ancient extinctions and ecosystem shifts, offering insights relevant to today's biodiversity crisis.

The work is ambitious: using sedimentary DNA to reconstruct ice age ecosystems and to understand the ecological consequences of human presence. Only two years into GACT, every dataset generates new questions. Every cave layer adds another twist to the story.

With hundreds of samples now being processed, major discoveries lie ahead. Researchers expect soon to detect the first cave bear genomes, the earliest human traces, and complex microbial communities that once thrived in darkness. Will the sediments reveal all their secrets? Time will tell — but the prospects are exhilarating.

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

Sistema Ox Bel Ha, meaning "three paths of water" in the local Mayan language, is a gigantic submerged labyrinth that runs for at least 326 miles (524 kilometers) underground, according to the Investigation Center of the Aquifer System of Quintana Roo (CINDAQ). This makes it the longest submerged system and the second-longest cave system in the world, after the 426-mile-long (686 km) Mammoth Caves in Kentucky.

The Yucatán Peninsula is home to several massive cave systems because it has a thin layer of top soil covering limestone, which is soluble, enabling rain water to quickly pass through into caverns below the surface, according to a 2020 study. This is also the reason why the region has few rivers or streams.

The caverns form through a process called karstification, in which rain water dissolves calcium carbonate from the limestone. In the case of Ox Bel Ha, this process is supercharged as the fresh water meets salt water that's entered the system from the ocean.

The fresh and salt water form distinct layers and meet at a point in the cave water called the halocline. This line varies in Ox Bel Ha, varying from 33 feet (10 meters) near the coast, where there is more salt water, to 66 feet (20 m) deep further inland. CINDAQ estimated that 27% of the system is salt water and 73% fresh water. This fresh water feeds the vast Maya aquifer, which is the only source of drinking water in the region.

The karstification process can cause cavern roofs to collapse, creating an exposed pool or sinkhole, known as a cenote. Ox Bel Ha has at least 160 cenotes, and they are important water sources for animals and ecosystems, according to CINDAQ. The organization has recently recorded a number of species around the cenotes, such as cougars (Puma concolor), jaguars (Panthera onca) and various deer and other animals.

The system also supports a range of creatures below the surface. In 2018, scientists discovered that the subterranean system supports its ecosystem with methane. Methane forms below the jungle floor and then migrates down into the caves, where microbes and bacteria consume it. These in turn become food for cave-dwelling crustaceans as well as several species of fish, including an eyeless albino cave fish.

Ox Bel Ha runs near the historical Maya town of Tulum. The ancient Maya believed that cenotes were gateways to Xibalba, the Maya underworld, and these pools, along with those of the nearby Sistema Sac Actun, have yielded a number of important archaeological finds.

Most notably, researchers found the remains of a 25- to 30-year-old woman, named Eve of Naharon, whose remains may date to 13,700 years ago — potentially making these the oldest human remains found in the Americas. However, a 2021 review noted that this date has not been replicated or verified. Evidence suggests the woman was deliberately placed on the cave floor, which wasn't flooded at that point, although this also isn't clear, a 2020 study noted.

Ox Bel Ha's system is under threat from construction and developments, including the Maya Train and Tulum International Airport, and it already runs under a number of urban areas, CINDAQ said. This makes studying and mapping the vast underwater system critically important, CINDAQ added.

Discover more incredible places, where we highlight the fantastic history and science behind some of the most dramatic landscapes on Earth

Scientists analyzing 1,300-year-old human feces from the Cave of the Dead Children in Mexico have discovered that people often dealt with nasty intestinal infections more than a millennium ago.

"Working with these ancient samples was like opening a biological time capsule, with each one revealing insight into human health and daily life," study lead author Drew Capone, an assistant professor of environmental health at Indiana University, said in a statement.

Capone and colleagues used molecular analysis techniques to study 10 ancient desiccated feces samples — also called paleofeces — found in a cave in Mexico's Rio Zape Valley just north of the city of Durango in northwestern Mexico, that dated from A.D. 725 to 920. The researchers published their findings Wednesday (Oct. 22) in the journal PLOS One.

In the late 1950s, archaeologists excavated the Cave of the Dead Children and recovered human and non-human paleofeces, plant remains and animal and human bones from a large trash heap. The cave was used by people from the prehistoric Loma San Gabriel culture, who practiced small-scale agriculture, produced unique ceramics, lived in small villages and occasionally practiced child sacrifice. Archaeologists named the cave after the skeletons of children found there.

Previous studies of paleofeces from the cave revealed the presence of hookworm, whipworm and pinworm eggs, suggesting the people who deposited their feces in the cave were infected by a variety of parasites.

In the new study, the scientists used cutting-edge molecular techniques to detect additional microbes in paleofeces from 10 "distinct defecation events" with the aim of expanding their understanding of the burden of disease among the Loma people. "There is a lot of potential in the application of modern molecular methods to inform studies of the past," study co-author Joe Brown, a professor of environmental sciences at the University of North Carolina at Chapel Hill, said in the statement.

The researchers extracted DNA from the 10 paleofeces samples and then used polymerase chain reaction (PCR) to amplify the DNA of the microbes in the feces. Every sample had at least one pathogen or gut microbe in it, and the two most common were the intestinal parasite Blastocystis, which can cause gastrointestinal issues, and multiple strains of the bacterium E. coli, which were found in 70% of the samples. Also identified were pinworms as well as Shigella and Giardia, which cause intestinal illnesses.

The high number of microbes discovered in the paleofeces "suggests poor sanitation among the Loma San Gabriel culture from 600-800 CE resulted in exposures to fecal wastes in the environment," the researchers wrote in the study. People likely ingested the microbes via feces-contaminated drinking water, soil or food, the team added.

While these pathogen-associated genes persisted in the paleofeces for up to 1,300 years, there may have been even more pathogens in the samples that have since decayed and are no longer detectable, the researchers noted in the study.

Still, the new analysis revealed the DNA of pathogens that were not previously found in paleofeces, including Blastocystis and Shigella.

"The application of these methods to other ancient samples offers the potential to expand our understanding of how ancient peoples lived and the pathogens that may have impacted their health," the researchers wrote.

Australia's First Nations history stretches back many tens of thousands of years, rich in depth and diversity.

Archaeological research has revealed much about this deep past, but it has rarely captured the gestures of the ancestors — their movements, postures and physical motions. Material traces like tools and hearths tend to survive; fleeting movements usually do not.

Newly published research in the journal Australian Archaeology has revealed something different: traces of hand movements preserved in soft rock deep within GunaiKurnai Country.

In a limestone cave in the foothills of the Victorian alps, a team of researchers led by the GunaiKurnai Land and Waters Aboriginal Corporation in partnership with Monash University and international archaeologists from Spain, France and New Zealand studied finger impressions dragged into the walls and ceilings. They reveal the hand movements of ancestors from thousands of years ago.

The glittering Waribruk

The cave, referred to by GunaiKurnai Elders as Waribruk, contains a pitch-black chamber beyond the reach of natural light. To enter and mark these walls, the ancestors would have needed artificial light: firesticks or small fires.

The cave's deeper interior walls became soft over millions of years as underground waters penetrated the limestone, slowly weathering and dissolving the rock into cavernous tunnels.

The remaining wall surfaces and ceilings became spongy and malleable, much like the texture of playdough.

Over time, cave-dwelling bacteria living on the soft, moist rock produced luminescent microcrystals, so that today, the walls and ceiling glitter when exposed to light.

It is on these glittering surfaces that the finger grooves are found.

We don't know exactly when they were made, but people would have needed artificial light to reach this part of the cave. They would have either carried firesticks or lit fires on the ground.

Archaeological excavations below and near the panels failed to uncover evidence of fires on the ground, but we did find millimeter-long fragments of charcoal and tiny patches of ash, likely dropped embers from firesticks.

These were found buried in the cave floor under and near the decorated walls. They date between 8,400 and 1,800 years ago, about 420 to 90 generations past.

This, then, is the best estimate for how long ago the old ancestors moved through the dark tunnels of the cave, firelight in hand, to create the finger impressions on the walls.

Rare ancestral gestures

What they made when they dragged their fingers along the soft rock surfaces deep in the cave is remarkable, revealing rare evidence of ancestral gestures: fleeting bodily movements captured in soft cave surfaces.

On one panel, 96 sets of grooves were recorded. The first marks run horizontally, made by multiple fingers, sometimes both hands side by side. Later, vertical and diagonal grooves were added, intersecting the earlier ones.

Among them are two parallel sets of narrow impressions, only 3 to 5 millimeters [0.1 to 0.2 inches] wide for each finger. They are each set a short distance apart, indicating they were made by a small child. However, they're so high up, the child must have been lifted by an adult.

Deeper in the cave, a low ceiling panel bears 262 grooves above a narrow clay bench sloping steeply toward a creek bed. The grooves indicate people moved along the ledge, crawling, sitting, or balancing to reach the ceiling.

Farther along, 193 grooves trace a path above the creek bed. Fingers were pressed into the soft ceiling, gradually releasing 1.6 meters [5.3 feet] farther along as the people walked forward.

All impressions point the same way, suggesting arms and hands raised overhead, capturing a deliberate, embodied gesture as the ancestors moved deeper into the cave.

A place only few could enter

Altogether there are 950 sets of finger grooves deep within Waribruk. Their meaning remained unclear for years, but a close analysis of where the marks appear, and where they don't, offers key insights.

The grooves are always located in areas where calcite microcrystals coat the cave walls or ceiling, sometimes just extending past the glitter's edges. They never appear in areas of the cave where the soft walls are without glitter.

Crucially, they occur far from any archaeological evidence of domestic life: no hearths, no food remains, no tools.

This absence matters. GunaiKurnai oral traditions hold that such caves weren't used for ordinary living. They were only frequented by special individuals, mulla-mullung — medicine men and women who wielded powerful knowledge.

Mulla-mullung healed and cursed through ritual, using crystals and powdered minerals as part of their practice.

In the late 1800s, GunaiKurnai knowledge-holders told the pioneer ethnographer Alfred Howitt about the powers of these crystals, and of the caves. The role of mulla-mullung, they explained, was usually passed on from parent to child, and when a mulla-mullung lost their crystals, they lost their powers.

The finger grooves at Waribruk matches these traditions. They are not casual decorations. They are deliberate gestures, linked to crystal-coated surfaces, made in places only a few could enter.

The grooves reflect movement, touch, and sources of power for special individuals in the community: an embodied record of people interacting with the sacred.

What survives is not just ancient "rock art." These are the gestures of ancestors, mulla-mullung it now seems, who ventured into the deepest darkness of the cave to access the power of the glittering surfaces.

Through these finger trails, we glimpse not only a physical act, but a cultural practice grounded in knowledge, memory and spirituality. A momentary movement, preserved in stone, connecting us to lives lived long ago — and breathing the cave to life through the actions of the ancestors and culture.

Acknowledgements: The authors are just three of the 13 authors of the journal article, including Olivia Rivero Vilá and Diego Garate Maidagan, who undertook the photography to create the digital 3D models of the panels to record and measure the size of the finger grooves.

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

A cave in Israel once thought to be linked to Jesus may in fact be the burial place of another person from his time: Salome, the sister of the Judaean king Herod the Great, a new study finds.

The idea is based on the ornaments and architecture of the site, which archaeologists say indicate that a member of the Herodian royal family may have been buried there in the first century B.C.; Judaea at that time was a client kingdom of the Roman Empire.

But the study's authors say it is possible that a different person named Salome may be buried there.

"It's not that I think it must be the tomb of Salome the sister of Herod," Vladik Lifshits, an archaeologist at the Israel Antiquities Authority (IAA), told Live Science. "I'm suggesting that this is one of the possibilities."

Lifshits is a co-author with IAA archaeologist Nir-Shimshon Paran of the study in the latest issue of the IAA journal 'Atiqot that suggests the "Cave of Salome" may have been the burial place of a Judaean royal.

The cave, about 30 miles (48 kilometers) southwest of Jerusalem, was famous in Byzantine times as a site of Christian pilgrimage, because a woman named Salome (a common name at the time) was said to have been a "midwife of Jesus."

Related: 1,900-year-old papyrus 'best-documented Roman court case from Judaea apart from the trial of Jesus'

Monumental architecture

The identification of the tomb with someone called Salome seems to have come from the discovery there of an ossuary — a casket for bones — labeled with that name. Jerusalem was conquered from the Byzantines by the Islamic Caliphate in the seventh century, but Christian pilgrims seem to have visited the cave until the ninth century. Exactly who is buried in the tomb is not known, however.

Looters rediscovered the cave about 40 years ago, and it was excavated by archaeologists in 1984; the IAA has now included it on the Judean Kings Trail, a 60-mile-long (100 km) route linking several archaeological sites in central Israel.

Artifacts excavated from the cave include hundreds of clay oil lamps from the eighth and ninth centuries, which archaeologists think were sold to Christian pilgrims so they would have light while exploring the dark cave.

Many of the original ornaments have now been stripped away, but Lifshits noted the monumental architecture — including a large courtyard at the entrance — indicated that a member of the royal family may have been buried there. The authors also discovered the remains of several luxurious villas nearby, which indicates the site once belonged to a very wealthy family.

Herodian royals

Herod I, also known as Herod the Great, was a native of the Holy Land's southern Idumean region who rose to power through his family's influence with the Romans and ruled Judaea from about 37 to about 4 B.C.

He appears in the Christian Bible as the jealous king who ordered the execution of all male infants in Bethlehem — an act known as the "Slaughter of the Innocents," which Jesus' family escaped (but most historians don't think this happened).

Despite Herod's savage reputation, he was considered a relatively good king in general.

For example, he was a prolific builder who restored the decrepit Second Temple on the Temple Mount, and the massive rock walls he had built are still standing today as the Wailing Wall in Jerusalem.

One member of the Herodian royal family named Salome was Herod's sister, a key figure in his court; and reports from the time say she colluded with him in the executions of other family members.

But Herod's granddaughter was also named Salome; according to the Christian Bible, she ordered the execution of John the Baptist, a Jewish preacher and associate of Jesus, and demanded that his head be brought to her on a platter.

The elder Salome died in about A.D. 10; historians think the younger Salome died in the 50s or 60s A.D.

Archaeologist Boaz Zissu of Israel's Bar-Ilan University who was not involved in the study, said the idea that the person buried in the Cave of Salome may have been Herod's sister was interesting but not conclusive.

"The authors correctly identify the original phase as a monumental tomb belonging to local elites of the Herodian period," he told Live Science in an email. But establishing that the tomb was for the Herodian Salome would demand "more rigorous evidential support," he said.

What do you know about Jesus Christ, the man? Test your knowledge of biblical archaeology

While investigating a cave high in the mountains of Mexico, a spelunker thought she had found a pile of trash from a modern-day litterbug. But upon closer inspection, she discovered that the "trash" was actually a cache of artifacts that may have been used in fertility rituals more than 500 years ago.

"I looked in, and it seemed like the cave continued. You had to hold your breath and dive a little to get through," speleologist Katiya Pavlova said in a translated statement. "That's when we discovered the two rings around the stalagmites."

The cave, called Tlayócoc, is in the Mexican state of Guerrero and about 7,800 feet (2,380 meters) above sea level. Meaning "Cave of Badgers" in the Indigenous Nahuatl language, Tlayócoc is known locally as a source of water and bat guano. In September 2023, Pavlova and local guide Adrián Beltrán Dimas ventured into the cave — possibly the first time anyone has entered it in about five centuries.

Roughly 500 feet (150 m) into the cave, the ceiling dipped down. The pair of explorers had to navigate the flooded cave with a gap of just 6 inches (15 centimeters) between the water and the cave ceiling. "Adrián was scared, but the water was deep enough, and I went through first to show him it wasn't that difficult," Pavlova said.

While taking a break to look around, Pavlova and Beltrán were shocked to discover 14 artifacts.

"It was very exciting and incredible!" Pavlova said. "We were lucky here."

Related: 2,500-year-old burials of 3 people discovered in a cave in Mexico

Among the artifacts were four shell bracelets, a giant decorated snail shell (genus Strombus), two complete stone disks and six disk fragments, and a piece of carbonized wood. Pavlova and Beltrán immediately contacted Mexico's National Institute of Anthropology and History (INAH), which sent archaeologists to recover the artifacts in March.

Given the arrangement of the bracelets — which had been looped over small, rounded stalagmites with "phallic connotations" — the archaeologists speculated that fertility rituals were likely performed in Tlayócoc cave, they said in the statement.

"For pre-Hispanic cultures, caves were sacred places associated with the underworld and considered the womb of the Earth," INAH archaeologist Miguel Pérez Negrete said in the statement.

Three of the bracelets have incised decorations. An S-shaped symbol known as "xonecuilli" is associated with the planet Venus and the measurement of time, while the profile of a human-like figure may represent the creator god Quetzalcoatl.

Pérez dated the artifacts to the Postclassic period of Mesoamerican history, between A.D. 950 and 1521, and suggested that they were made by members of the little-known Tlacotepehua culture that inhabited the region.

"It's very likely that, because they were found in a close environment where humidity is fairly stable, the objects were able to survive for so many centuries," Pérez said.

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

Archaeologists in Israel have discovered five burials in a cave belonging to an enigmatic human lineage that suggest this group shared aspects of its lifestyle, technology and burial customs with modern humans and Neanderthals, who also lived in the region up to 130,000 years ago, a new study reports.

The finding reveals that Neanderthals, modern humans and related human lineages coexisted in what is now Israel for about 50,000 years. However, it's unknown which group influenced the other and in what direction.

In the new research, scientists investigated caves in the Levant — the eastern Mediterranean region that today includes Israel, the Palestinian territories, Jordan, Lebanon and Syria. Researchers have long thought the Levant was a key gateway for our species, Homo sapiens, and other branches of the human family tree that migrated out of Africa.

Prior work suggested that during the mid-Middle Paleolithic (80,000 to 130,000 years ago), the southern Levant was home to at least three different groups of Homo: modern humans, Neanderthals and a third lineage resembling both modern humans and Neanderthals that was unearthed at the prehistoric site of Nesher Ramla in central Israel. Although these groups were physically different from one another, researchers weren't sure how similar they were in terms of lifestyle.

Artifacts found at Nesher Ramla suggested that the site had been a temporary hunting and butchering camp, so the researchers looked nearby for the main base of operations. "Such sites are usually found in caves," study lead author Yossi Zaidner, a Paleolithic archaeologist at the Hebrew University of Jerusalem, told Live Science.

Zaidner and his colleagues focused on Tinshemet Cave about 6 miles (10 kilometers) away from Nesher Ramla. Scientists first discovered the cave in 1940, and new excavations there unearthed five burials belonging to Homo — the first such burials from the mid-Middle Paleolithic found in this region in more than 50 years. It's currently unknown if these burials belong to early modern humans, human-Neanderthal hybrids, the mysterious other lineage or another group entirely.

Related: Neanderthals and early Homo sapiens buried their dead differently, study suggests

The researchers also uncovered stone artifacts made with the Levallois technique, meaning they are humped on one side, flat on the other and had sharpened edges. In addition, the human remains were buried in fetal positions, often with the red mineral pigment ocher, which prior research suggested was linked with funerary practices and symbolic thought. The scientists also discovered bones of large game such as aurochs (Bos primigenius, an extinct cowlike species), horses, deer and gazelles.

"The discoveries at Tinshemet Cave are probably going to be the most important finds in the region from the last 50 years," Chris Stringer, a paleoanthropologist at the Natural History Museum in London who was not involved in the new study, told Live Science.

Multiple humans at multiple caves

These findings at Tinshemet Cave were very similar to discoveries made in two other caves in Israel — Skhul Cave and Qafzeh Cave — that also date to the mid-Middle Paleolithic. However, the skeletal remains in each cave were significantly anatomically distinct from those of the other caves.

The researchers suggest that different groups of Homo not only coexisted in the mid-Middle Paleolithic in the Levant, but shared a number of key practices, exchanging innovations such as burial rites and the symbolic use of ocher for about 50,000 years. It remains uncertain in which direction these practices were exchanged — say, if modern humans adopted Neanderthal hunting strategies, or if Neanderthals embraced modern human burial rites, or if they came up with new practices together.

"Neanderthals' and Homo sapiens' interactions were not just sporadic encounters, but they had very substantial contacts which led to adoption of behaviors," Zaidner said.

The fact that groups of Homo from this time and place often share anatomical features of both modern humans and Neanderthals suggest "these are actually hybrids that are using the same culture," Zaidner said.

However, Stringer does not see a mixing of lifestyles. Instead, he suggested the burials and artifacts at the Tinshemet, Skhul and Qafzeh caves are linked only with H. sapiens, and that different behaviors discovered at later Levant sites such as the Kebara, Amud and Dederiyeh caves are linked with Neanderthals.

"That said, there is growing evidence that these populations overlapped in the region about 100,000 years ago more than has been supposed, and given what happened in Europe 50,000 years later, there was clearly potential for contact and both cultural and genetic exchanges," Stringer said. "I've tended to play down the possibility that the Skhul and Qafzeh samples show signs of hybridization with Neanderthals, but they do show a lot of morphological variation, and some of it could indeed be an indication of interbreeding with Neanderthal neighbors."

The scientists now plan to study the remains at Tinshemet Cave in greater detail to see if they are hybrids of modern humans and Neanderthals, Zaidner said.

"I eagerly await detailed descriptions of the morphology of the Tinshemet fossils," Stringer said. If interbreeding between modern humans and Neanderthals did happen in the Levant, "and I agree it seems increasingly likely, then somewhere there must be actual first-generation Neanderthal-sapiens hybrids waiting to be discovered or recognized," Stringer added.

The researchers detailed their findings online Tuesday (March 11) in the journal Nature Human Behavior.

Researchers have discovered a never-before-seen golden cave fish in southwestern China that's still evolving to survive underground.

The scaleless fish is a previously unknown species of golden-line fish (Sinocyclocheilus), which are only found in and around Chinese caves. The discovery therefore offers scientists a window into the evolution of these unusual cave-dwelling creatures.

Some golden-line fish have lost their scales and eyes as part of adaptations to cave life — there's no point having eyes if it's too dark to see anything. The newfound species, which the researchers named "Xingren golden-lined fish" (S. xingrenensis) after the city close to where it was found, has large eyes but no scales, suggesting it is still evolving to suit its conditions, according to the study, published Feb. 24 in the journal Zoosystematics and Evolution.

Previous research suggested that golden-line fish moved into caves when China was drying up — so there was less water outside — towards the end of the Miocene epoch (23 million to 5.3 million years ago) and in the Pliocene epoch (5.3 million to 2.6 million years ago). By examining the evolutionary history of golden-line fish, the study authors found that Xingren and others like it probably lost their scales during the Pleistocene (2.6 million years to 11,700 years ago), similar to when some members of the group supposedly started losing their eyes.

"This further suggests that most cave fishes may not have lived in cave ecosystems for more than a few million years," the researchers wrote in the study. "Thus, together with the eyes and scales, we hypothesize that the new species may be undergoing a gradual evolutionary process towards caves."

Related: Do fish get thirsty?

Sinocyclocheilus is the most diverse group of cave fish in the world with 80 recognized species — the Xingren golden-line fish makes 81. Researchers found this latest addition to the group while collecting golden-line fish in southwestern Guizhou province between 2012 and 2020, according to the study.

Golden-line fish are strikingly varied in appearance. The newfound species differs from known golden-line fish thanks to a unique combination of features, including having a scaleless body with irregular black markings. Xingrens also lack a horn-like structure present on some golden-line fish, notably S. longicornus, a unicorn-like blind fish discovered in 2023.

Researchers still have much to learn about Xingrens, but their eyes offer some clues about how this species lives. The researchers suggested that Xingrens' lives are linked to photoperiods, which are the lengths of daylight periods an organism receives within 24 hours. After all, Xingren eyes are significantly larger than the blind fish found in total darkness deep in caves, and can therefore still detect light.

"This is related to the habitat, where the new species can be connected to surface streams through cave windows, and their life rhythms may be closely related to photoperiods," the study authors wrote.

Caves are natural shelters. Throughout our history, humans have made extensive use of them as spaces to create art, inter the dead and butcher animals for food and clothing. In this countdown, Live Science takes a look at seven incredible caves that people used over the ages, leaving behind evidence of their crafts, dead and leftovers. Some of the caves were used by our now-extinct relatives, including the Neanderthals, Denisovans and Homo erectus.

Lascaux cave

Lascaux cave in southwestern France contains about 680 painted frescoes and 1,500 engravings that were created around 21,000 years ago, according to the French Ministry of Culture. Much of the artwork shows animals, including depictions of horses, bison, deer, bears and aurochs (Bos primigenius) — a species of now-extinct bovine. The artwork also features geometric elements, including dots, lines and pentagonal shapes. One of the paintings may show a human figure with a bird-like head, possibly someone wearing a mask. At the time the art was created, people were living as hunters and gatherers, and it's possible that rituals of some form took place in the cave.

Chauvet cave

Chauvet cave in southeastern France has drawings and engravings that date to around 32,000 years ago, according to the Metropolitan Museum of Art in New York City. The cave's interior includes images of horses, bears, lions, rhinoceroses, deer, panthers, bison, owls and mammoths. The remains of human handprints have also been found inside Chauvet. Many of the drawings were created using either red or black ochres. There is one enigmatic image that shows the lower half of a woman's body alongside what appears to be a bison.

Zhoukoudian caves

Located near Beijing, China, the Zhoukoudian caves contain remains of our ancestor H. erectus — sometimes called "Peking man." Many of the fossils were lost during World War II, but excavations have been carried out at the site in recent times with a team carrying out a re-excavation of the cave in 2012. Scientists have found the remains of stone tools that were used for scraping and softening animal hides. These hides were probably used as clothing. It's still debated when Peking man used the caves, but it may have been at different times between roughly 200,000 and 800,000 years ago. Homo sapiens also made use of the caves around 18,000 to 11,000 B.C., UNESCO reports. Remains of their burials have been found within the caves.

Cave of Swimmers

The "Cave of Swimmers" is located in southwestern Egypt in an area that is now arid and has relatively little plant and animal life. The cave gets its name from rock art that depicts people who appear to be swimming. Other art in the cave shows people who appear to be running, walking or engaged in other activities. There are also images of human handprints and an engraved antelope's hoofprint, according to the British Museum. The artwork's age is a matter of debate, but it may have been created between 6,000 and 9,000 years ago — a time when the environment in the region was much wetter.

Denisova cave

Denisova cave is located in Siberia, Russia. A hermit named Denis lived there in the 1700s, which is how it became known as the "cave of Denis" in Russian. The cave's archaeological remains indicate that at least three hominins — H. sapiens, Neanderthals and Denisovans — likely occupied the site at different points in time. Stone tools found in deep layers indicate the cave's earliest residents lived there around 300,000 years ago, the University of Oxford reported.

Other finds include hominin bones and teeth, as well as the bone of a 13-year-old girl who was a Denisovan-Neanderthal hybrid. Archaeologists have also unearthed pendants made of animal teeth that date back between roughly 43,000 and 49,000 years ago that were likely made by H. sapiens. The remains of stone tools that were likely used for butchering animals have also been discovered.

Atapuerca caves

The caves of the Sierra de Atapuerca in Spain were used by people from nearly 1 million years ago to modern times, according to UNESCO. Neanderthals and Homo sapiens both used the caves, and Homo antecessor, Homo heidelbergensis and H. erectus may also have used them. The remains of tools and animal bones indicate that people were butchering bison in the caves about 400,000 years ago. Rock art, both painted and engraved, has been discovered in the caves and includes depictions of animals, people and geometric motifs.

Cave of Altamira

The cave of Altamira in Spain was used by humans roughly 36,000 to 13,000 years ago, according to the Bradshaw Foundation. The cave is about 885 feet (270 meters) long and contains a vast amount of rock art. (A replica of the rock art is seen above). Perhaps the most remarkable example is a ceiling with colorful paintings depicting 25 bison that are up to 5.6 feet (1.7 m) in length, alongside two horses and a deer. To create this ceiling artwork, prehistoric artists engraved and outlined the figures and then colored them in with paint made from ochre, the foundation notes.

A granite boulder carved more than 35,000 years ago deep in a cave in Israel may be the oldest evidence of ritual practices in the Holy Land, a new study suggests.

The grooves carved into the boulder look strikingly similar to the pattern of a tortoise shell. While it's unknown what this design means, it's possible that this was an ancient symbol of unification, according to study co-author Israel Hershkovitz, a physical anthropologist at Tel Aviv University.

In that case, it may be that the sections of the shell, known as "scutes," may have represented distinctive groups of people who had been integrated into the ancient society, Hershkovitz told Live Science.

The ritual boulder was discovered deep within Manot Cave, in the Galilee region of northern Israel, where Hershkovitz has led excavations since 2010.

The cave was discovered by construction workers in 2008 and the archaeological work initially involved areas near the cave's entrance where prehistoric people lived, carrying out activities such as shaping stone tools, butchering animals and eating, Hershkovitz said. But the team didn't discover the ritual boulder deep in the cave until 2013, he said.

"It was quite a surprise, because we were concentrating close to the entrance, where there was more light and people were living," he said. But "it was so dark and deep there, we rarely visited that part."

Related: Evidence of Assyrians' conquest of Holy Land discovered in Jerusalem

Turtle rock

According to the study, the chamber containing the carved boulder was separated from the living areas behind a gallery of large stalagmites and stalactites.

The granite boulder weighs more than 60 pounds (28 kilograms) and is a little less than a foot (30 centimeters) across. It was discovered in a niche in the back wall of the chamber and was the only artifact found nearby.

The rock's upper surface is carved with deep grooves; the authors noted that the carving was made at roughly the same time as some of the oldest known cave paintings in France.

Although there may be some earlier evidence of ritual practices by modern humans, such as the 40,000-year-old "lion man" stone figurine from a cave in Germany, the study noted that the boulder in the Manot Cave is the earliest evidence of ritual practices in the eastern Mediterranean region.

Ancient cave

Examinations of the ritual boulder suggest the grooves were deliberately carved with flint tools, while analysis of the calcite crusts in some of the grooves date it to between 35,000 and 37,000 years ago, according to the study, published Dec. 9 in the journal PNAS.

The dating places the carved boulder within the Early Upper Paleolithic period, from about 33,000 to 48,000 years ago, when Homo sapiens hunter-gatherers were adding new stone tool technologies to much older ones.

According to the study, particles of wood ash found in the outer layers of the stalactites and stalagmites within the boulder chamber indicate that it was illuminated by fire, possibly during ritual gatherings. Acoustic tests also revealed that the chamber was "well-suited for communal gatherings," by facilitating conversations, speeches and hearing, the researchers found.

"Our data from Manot Cave testified to the existence of some initial forms of collective ritual practices already in the Early Upper Paleolithic," the authors wrote. "The existence of a ritual compound at Manot Cave is not surprising … [It was] a successful adaptive strategy to cope with the large demographic and economic challenges human society faced in the Upper Paleolithic."

The Marble Caves are natural rock formations with curved walls covered in swirling mineral patterns. They sit on the shores of General Carrera Lake, a glacial lake in southern Chile. The lake floods the caverns with turquoise waters, which fill the caves with blue light and give them an ethereal appearance.

The Marble Caves are so smooth, they look like they've been hollowed out with an ice cream scoop. But the caves formed due to the slow action of lake water, which dissolved minerals in the rocks until the walls crumbled. Researchers think this occurred over the past 10,000 to 15,000 years, after glaciers retreated from the region and exposed its stone to weathering.

Related: Cave of Crystals: The deadly cavern in Mexico dubbed 'the Sistine Chapel of crystals'

"After the glaciers retreated, the lake was created, and that was when the process of sculpting the [caves] began," Francisco Hervé Allamand, a professor of geology at Andrés Bello National University in Chile and an honorary fellow of the Geological Society of America, told the BBC in 2019.

The stone in the caves was originally limestone, a sedimentary rock made of calcium carbonate. But it transformed into marble, which is a metamorphic rock, under high heat and pressure before the caverns opened, Hervé Allamand said. Limestones are some of the most soluble rocks in the world, he said, meaning they are extremely susceptible to erosion from water.

The original limestone formed closer to the equator than Chile sits today and drifted southward millions of years ago as tectonic plates shifted around Earth, Hervé Allamand said. This grinding journey jumbled up Earth's crust and buried rocks so deep that they became exposed to blistering temperatures of 570 to 750 degrees Fahrenheit (300 to 400 degrees Celsius). Together with the pressure from plate movement, this heat recrystallized the limestone into whitish-gray marble and created ripples of brown and yellow rock where impurities were trapped in the limestone.

"When a rock undergoes metamorphosis, new minerals are formed," Hervé Allamand said, referring to brown and yellow veins within the marble.

Reflections off the water in the Marble Caves give rise to stunning images that shift depending on the light and water levels. The water owes its brilliant azure color to glacial silt, which is also known as "rock flour." This fine stone powder absorbs the shortest wavelengths of light — the purples and indigos — and reflects mainly light-blue and green light back to the surface, giving the water a turquoise tint. (Water absorbs longer wavelengths of light that give rise to red, orange and yellow.)

The turquoise water may look like a tropical sea, but its glacial origin means it's freezing.

The Marble Caves are accessible only by water, and they are best explored with kayaks, which enable visitors to wind in and out of the curved walls, according to the travel website Swoop Patagonia.

Discover more incredible places, where we highlight the fantastic history and science behind some of the most dramatic landscapes on Earth.

Hang Son Doong is the world's largest known cave, with enough space in some of its passages to fly a Boeing 747 airplane through them. The limestone cavern sits beneath a lush jungle in Vietnam's Phong Nha-Ke Bang National Park and hosts primeval forests that thrive thanks to giant "skylights" in the rock.

Hang Son Doong cave — the name means "Mountain River" — is young compared with other limestone caves. It formed 2 to 3 million years ago inside the biggest limestone massif in Asia, a colossal block of rock more than 400 million years old that was born from the compressed shells and skeletons of ancient sea animals. Two rivers — the Rao Thuong and the Khe Ry — coursed through cracks in the limestone and eroded the rock, forming a giant tunnel in the massif that only recently came to be known as Son Doong.

Related: China's 'heavenly pits': The giant sinkholes that have ancient forests growing within

Ho Khanh, a resident of Vietnam, discovered the cave by chance in 1990 while hunting in the jungle. "He felt a blast of wind and heard the rush of a river inside," Howard Limbert, a British cave explorer and technical director at Oxalis Adventure, a company that operates tours of Son Doong, told CNN. "But after he left, he couldn't find it again, because it's surrounded by foliage."

Years later, Khanh managed to retrace his steps. In 2009, he led a caving team from the British Cave Research Association that included Limbert to the cave's entrance. "We realized right away that it was major," Limbert said.

The team surveyed Son Doong and found it was the largest natural cave ever recorded. Their measurements indicated a total cave volume of 1.35 billion cubic feet (38.5 million cubic meters), which is spacious enough to fit nearly 15 Great Pyramids of Giza.

But researchers recently discovered the cave is even bigger than that. A diving expedition in 2019 revealed that Son Doong is connected to another cave called Hang Thung through an underwater tunnel. This link adds 57 million cubic feet (1.6 million cubic meters) to the cave's volume, or two-thirds of a Great Pyramid.

"It would be like someone found a lump on top of Mount Everest, making it another 1,000 meters [3,280 feet] higher," Limbert said. "Any cave in the world will be able to fit comfortably inside Son Doong when it's connected — it's just outrageous in size."

Son Doong is home to one of the world's tallest stalagmite, a monster pillar dubbed the "Hand of Dog" measuring 260 feet (80 m) high. The cave is divided into three sections — the entrance, the fossil passages and the muddy Passchendaele Passage (named after the World War I Battle of Passchendaele, which soldiers fought in mud-filled trenches) — that each boast spectacular formations.

As their names suggest, the fossil passages are filled with the remains of sea creatures that once inhabited an ancient sea in what is now central Vietnam. The Passchendaele Passage is home to a 300-foot (90 m) wall of calcite known as the Great Wall of Vietnam, which cave explorers only managed to scale on their second visit to the cave in 2010.

Finally, at the heart of Son Doong, the limestone ceiling collapsed long ago to form two sinkholes that allow beams of light to shine into the cave. And under these "skylights," two jungles have thrived for thousands of years.

Name: Cave of Swimmers

What it is: A series of rock paintings depicting a group of people swimming

Where it is from: Egypt's Western Desert

When it was made: Between 6,000 and 9,000 years ago

Related: Jade burial suit: 2,000-year-old 'immortality' armor worn by Chinese royalty

What it tells us about the past: Thousands of years ago, the Sahara Desert was not the dry, sandy landscape we know it as today — it was a lush, green oasis. In fact, the sandstone-rich Gilf Kebir plateau, which stretches from southwestern Egypt into southeastern Libya and is where the rock art resides, offers further evidence that this swath of land was once accessible to bodies of water and not always a barren desert.

In 1926, the remote area was mapped by European cartographer László Almásy who stumbled upon two "side-by-side shallow caves" adorned with hundreds of rock paintings of animals and humans, including handprints that would have been created by someone "blowing pigment onto the rock face over splayed fingers," according to The British Museum. 

But one set of drawings stood out to researchers: a pair of humans with their arms and legs splayed out as if they were swimming. Many researchers think the paintings offer a glimpse of what daily life would have looked like before the region became a desert. However, some think the depictions are more metaphorical.

The artwork reached pop culture status when it was featured in author Michael Ondaatje's book "The English Patient" (McClelland & Stewart Inc., 1992) and, later, in the 1996 film of the same name, according to the Bradshaw Foundation.

Archaeologists investigating caves in Malaysia ahead of their flooding for a hydroelectric reservoir have discovered more than a dozen prehistoric burials they think are up to 16,000 years old.

The caves, in the remote Nenggiri Valley about 135 miles (215 kilometers) north of Kuala Lumpur, will be underwater if the reservoir fills as planned in mid-2027, creating a 20-square-mile (53 square km) lake to feed a 300-megawatt hydroelectric power station.

Zuliskandar Ramli, an archaeologist at the National University of Malaysia, told Live Science that most of the skeletons seemed to be from the pre-Neolithic culture of the region.

Some scholars suggest this was a branch of the hunter-gatherer Hoabinhian culture, who made distinctive stone tools found in other parts of Southeast Asia, from southwest China to Indonesia. Scientists also think the Hoabinhian peoples used many wild plants — including pepper, broad beans and betel nut — that are domesticated in the region today.

Ramli, who led the excavations at the Nenggiri Valley, said his team had found a total of 16 individuals buried in 13 limestone caves at four sites.

Related: Look into the eyes of a Stone Age woman in this incredibly lifelike facial reconstruction

Cave finds

Fifteen of the skeletons were buried in a crouched or "fully flexed" position, which indicates a pre-Neolithic burial in this region, Ramli said. But the other skeleton had been buried in an extended position, and dating of the sedimentary layers in the cave, including radiocarbon dating, suggested it originated in the Neolithic period about 6,000 years ago.

As well as the 16 skeletons, the archaeologists recovered more than 71,000 prehistoric artifacts from the caves.

Many are worked fragments of stone tools, but the excavators also found thousands of pieces of pottery, as well as stone ornaments.

Malaysia's government-owned Bernama news agency reported that the archaeological work at the Nenggiri Valley sites began in March 2022 and concluded in October 2023. One of the most important finds was a complete human skeleton in a cave called Gua Keledung Kecil that is estimated to date between 14,000 and 16,000 years old.

"This is the most complete and oldest skeleton in a fully flexed position found in the country," Ramli told Live Science.

Grave goods

Many of the artifacts were grave goods that had been deliberately buried in the caves with the dead, Ramli said. In the pre-Neolithic graves, they commonly included stone tools; hematite minerals, or red ochre; and crystals.

In the grave from the Neolithic period, however, the burial goods included a stone bracelet, polished stone tools and pieces of pottery, he said.

The Nenggiri hydroelectric project is expected to cost $5 billion Malaysian Ringgit, or more than $1 billion USD.

As well as providing electricity to Malaysia's power grid and water for irrigation projects, the dam's construction is expected to provide 2,000 jobs to the Indigenous Orang Asli and other local people, Bernama reported.

But critics say the dam will negatively impact Orang Asli villages along the Nenggiri river and submerge ancestral lands and forests.

A submerged, human-constructed limestone bridge found inside a cave on a Spanish island is much older than previously thought, pushing back the record of when humans inhabited the location, a new study finds.

Researchers discovered the limestone bridge in 2000 during a scuba-diving expedition inside the flooded cave in Mallorca, a Mediterranean island located off the eastern shore of Spain's mainland. At the time, researchers determined that the 25-foot-long (7.6 meters) bridge, which consists of large limestone blocks stacked on top of each other, was built around 4,400 years ago, according to a study published Friday (Aug. 30) in the journal Communications Earth & Environment.

"This dating was based on pottery fragments that were found inside the cave," lead author Bogdan Onac, a professor of geology at the University of South Florida, told Live Science. "But now we know that this [date] was wrong."

In addition to the broken artifacts, the cave was littered with bones from a now-extinct goat-antelope known as Myotragus balearicus, according to a statement from the university.

However, when people occupied the cave still remained unclear.

Related: Ancient humans used cave in Spain as burial spot for 4 millennia, 7,000 bones reveal

Even though Mallorca is a large island, it was one of the last to be inhabited in the Mediterranean. In contrast, Cyprus and Crete are considered to be the earliest islands in the area and were occupied at least 9,000 years ago, according to a study in the journal Science. 

To determine the true date of the bridge's construction, researchers studied a "distinct light-colored band" — akin to a "bathtub ring" — running along the bridge's upper portion, according to the study. The shift in coloration shows changes in sea level, as well as the development of calcite encrustations that formed on the bridge when the water rose.

Upon analyzing the mineral deposits, which are also known as speleothems, researchers determined that the bridge was constructed approximately 6,000 years ago, pushing back the timeline of human presence on the island by 1,600 years.

"This testifies that the sea level sat there for a couple hundred years, allowing the mark to happen," Onac said. "The time when the bridge was constructed also shows that people were utilizing this cave much earlier than previously thought, closing the gap between eastern and western Mediterranean settlements."

The researchers said further research is necessary to determine why Mallorca was settled later than other islands in the region, but it could be because the island lacked resources needed for survival, such as farmable land.

Turkey's "fairy chimneys" are natural yet surreal-looking spires up to 130 feet (40 meters) tall that were carved out of soft volcanic rock by the elements over millions of years. Thousands of these spindly chimneys are peppered across the Love Valley in Göreme National Park, forming a rocky wonderland that human civilizations have taken refuge in for nearly 4,000 years.

Volcanic activity that began roughly 14 million years ago laid the foundation for the jagged landscape we see today. A series of eruptions showered what is now Central Anatolia with ash, which solidified into thick layers of tuff — a type of light, porous rock. Subsequent explosions then coated the tuff with lava that hardened into a tough, basalt crust. The chimneys, technically called "hoodoos," formed over the eons as wind and water went to work on the rocks, wearing down the tuff and leaving behind only pillars. The basalt eroded more slowly, which is why many of the chimneys are capped with mushroom-like basalt tops to this day.

Related: Cave of Crystals: The deadly cavern in Mexico dubbed 'the Sistine Chapel of crystals' 

Nature did the heavy lifting, but humans also helped to shape the fairy chimneys. The landscape is honeycombed with caves and tunnels dating as far back as the Hittites, who inhabited the area between 1800 and 1200 B.C., according to National Geographic. Central Anatolia later straddled the boundaries of rival empires — including the Greek, Persian, Byzantine and Roman empires — and frequent turmoil drove the region's residents to dig out hiding places among and beneath the spires. Christians fleeing persecution in ancient Rome even carved churches and monasteries out of the soft stone, expanding cave and tunnel networks into sprawling underground cities.

The density of living quarters hidden among the fairy chimneys is so vast it is "one of the world's most striking and largest cave-dwelling complexes," according to UNESCO. The agency inscribed Göreme National Park and the rock sites at Cappadocia on its list of World Heritage Sites in 1985.

The fairy chimneys have also been dubbed "the world's most unusual high-rise neighborhood" by National Geographic.

Discover more incredible places, where we highlight the fantastic history and science behind some of the most dramatic landscapes on Earth.

Cave art of a lion with a luscious mane drawn deep in a Puerto Rican cave about 500 years ago might have been created by an enslaved African, new research suggests.

"We have an image that looks like a lion — but in Puerto Rico, we don't have lions," project researcher Angel Acosta-Colón, an adjunct professor of geophysics at the University of Puerto Rico at Arecibo and an expert on the island's caves, said in a statement.

Instead, the drawing may have been made by someone who'd seen one in Africa before they were enslaved and taken to the island by the Spanish.

The idea was controversial, Acosta-Colón said. "But the age of the art is around [A.D.] 1500," he said. "We have data to corroborate what, I think, is one of the first [examples of] slave art in caves in Puerto Rico."

Acosta-Colón and Reniel Rodríguez Ramos, an archaeologist at the University of Puerto Rico at Utuado, have radiocarbon-dated some of the drawings in Puerto's Rico's caves to more than 2,000 years ago, according to unpublished research presented Oct. 18 at the Geological Society of America's annual conference in Pittsburgh.

Related: Warty pig is oldest animal cave art on record

Their discovery refutes a colonialist claim that people had lived on Puerto Rico for only a few hundred years before 1493, when the Italian navigator Christopher Columbus claimed the Caribbean island for his patrons in Spain.

Ancient evidence

Determining the age of rock art is difficult. Substances like the mineral ochre often used to inscribe them can't be reliably dated, and some of the drawings are superimposed on others. Oftentimes, the age of cave art in Puerto Rico is estimated by linking it to nearby artifacts that have datable organic material, Acosta-Colón said.

To acquire more accurate dates, Acosta-Colón and Rodríguez took samples of 61 pigments used to make drawings in 11 caves on La Isla Grande, Puerto Rico's main island. The sampling destroys a tiny part of the drawing — between 1 and 2 milligrams (35 millionths to 7 millionths of an ounce) of the pigment — so the researchers were careful to sample only cave art that was commonly seen.

Many of the pigments turned out to be made of a black organic material, and radiocarbon dating revealed that the cave drawings were made in three phases: the earliest, of abstract and geometric shapes, dated to between 700 and 400 B.C.; the second phase, with simple shapes of human bodies, dated to between A.D. 200 and 400; and the third phase, with more detailed portrayals of humans and animals, started between 700 and 800.

The discovery of the earliest phase was key. "That is very important to us," Acosta-Colón said. "This proves that we were here [thousands] of years before the European invasion."

Meanwhile, the last phase continued through the period of European colonization after about 1500 and included pictures of horses, ships and other animals, such as the lion.

This feline was likely painted by someone who had actually seen a lion, possibly an enslaved person from Africa who had been brought to the island by the Spanish, Acosta-Colón said.

The cave drawings illustrate the history of the Puerto Rican people, Acosta-Colón said. "Normally we get the European history version of Puerto Rico, but this is direct evidence that the story in Puerto Rico didn't start with the European invasion; it started much, much earlier in history," he said.

He thinks further research could push back the record of human history on the island to around 7,000 years ago. Recent research found some of the human remains from Puerto Rico were up to 3,800 years old.

Alice Samson, an archaeologist at the University of Leicester in the United Kingdom, wasn't involved in the research but has studied cave art on Puerto Rico's Mona Island. "This really important work … sheds light on thousands of years of human interaction with caves throughout precolonial and historic eras," she told Live Science in an email.

Jago Cooper, a professor of art and archaeology at the University of East Anglia in the U.K., wasn't involved in the research but worked alongside Samson on Mona Island.

"Such advances will help untap the huge cultural reservoir of knowledge preserved in the spectacular cave-scapes across the Caribbean," he told Live Science in an email.

Editor's note: Updated at 5:25 p.m. EDT to fix the conversion from milligrams to ounces.

Many cultures around the world choose to honor deceased loved ones through burial. The ceremonies that accompany this ritual are steeped in history and tradition and can vary from culture to culture. But when was the first human burial?

There's no definitive answer because not all burial sites are preserved, let alone discovered and studied. But the earliest evidence so far points to the Middle Paleolithic (around 300,000 to 30,000 years ago).

"By at least 120,000 years ago we have what we believe are deliberately buried human bodies," Mary Stiner, a professor of anthropology at the University of Arizona, told Live Science.

Stiner doesn't rule out the potential for older burials to exist but said the most convincing early examples for modern humans (Homo sapiens) burying their dead come from the Middle Paleolithic. Some controversial research has suggested that extinct human relatives buried their dead around 300,000 years ago in what is now South Africa, but this is disputed in the scientific community.

Related: What's the earliest evidence of humans in the Americas?

The earliest known anatomically modern human burials from 120,000 years ago are in caves such as Qafzeh Cave in what is now Israel. There's also evidence of Neanderthal burials in the same caves dating to 115,000 years ago, according to The Australian Museum. Stiner noted that people used caves a lot during the Middle Paleolithic — living, eating and socializing in them.

Researchers like Stiner are confident that these early cave burials were a deliberate human act — not an act of nature like a cave collapse — because the bones are positioned in death postures such as the fetal position, together with human objects, and in some cases it's evident that older deposits of sediment were disturbed for a burial to take place.

"Someone has actually dug a hole and then infilled it with a jumble of cultural material," Stiner said. "We also find that these kinds of phenomena occur in clusters quite often in caves, so people were thinking, 'Okay, we're going to do this again with another body.'"

The origins of burial are not fully understood, but ancient humans would have had plenty of reasons to dispose of their dead both inside and outside of caves. Humans and many other animals have an "inherent aversion" to decay, Trish Biers, curator of the Duckworth Laboratory in the Centre for Human Evolutionary Studies at the University of Cambridge, told Live Science.

"When you have death and decay, you know that something's wrong, and it's actually a really unpleasant process" to witness, Biers said.

Humans would have needed a way to deal with corpses as they decomposed, started to smell and exposed the living to flies, pathogens and scavengers. Initially, burials or other forms of body disposal may have dealt only with these practical aspects of death, becoming more sophisticated later on.

The move toward increasingly complex burials wasn't necessarily linear. A study published in "The Oxford Handbook of the Archaeology of Death and Burial" (Oxford University Press, 2013) found that elaborate burials in Eurasia came and went in the Upper Paleolithic (45,000 to 10,000 years ago), and burials were mostly pretty plain, containing objects used in daily life.

The authors of the Eurasian study also wrote that it was difficult to draw firm conclusions about the nature and meaning behind Upper Paleolithic burials because relatively few have been found. Furthermore, ancient burials varied by region.

According to Biers, the way people buried their dead would have depended on a range of factors, including the environment and what materials people had available. Cremation burials didn't occur until much later, with the oldest one on record, known as Mungo Lady, dating to about 40,000 years ago in Australia.

"That's one of the things I love most about teaching on death and researching death practices is that they're so highly variable," she said.

Archaeological discoveries across the Americas have shaped our understanding of when and how humans first reached the so-called New World. The story told by artifacts unearthed from sites all the way from Alaska to Chile is hotly debated.

According to the Clovis First theory, people crossed from Siberia into North America just over 13,000 years ago via the Bering Land Bridge — a mass of land that emerged when the last ice age lowered sea levels — and spread across the Americas.

But in recent decades, archaeologists have unearthed much earlier evidence of people across North and South America, pushing back the date for this milestone in human history and casting doubt on how the first Americans got there.

From giant sloth bones carved into pendants to underwater caches of mastodon bones, here are 13 of the oldest archaeological sites in the Americas.

1. Clovis, New Mexico

Close to a ravine called Blackwater Draw in eastern New Mexico sits an archaeological site, discovered in 1929, that has shaped our understanding of how the Americas were peopled.

The site was called Clovis due to its proximity to a town of that name and, throughout the 1930s, yielded stone artifacts, hearths and bones belonging to extinct animals — including mammoths — showing evidence of butchery dating to 13,000 years ago.

Spearpoints discovered in Clovis have come to define a group of people who were long believed to be the first humans to arrive in the Americas, as well as their culture. These distinctive spearpoints were chipped from stone into finger-long projectiles that are now known as "Clovis points" and were found associated with animal bones.

Ancient archaeological sites across the Americas are defined in relation to Clovis, with "pre-Clovis" sites referring to evidence that humans came from Asia far earlier than 13,000 years ago.

2. Swan Point, Alaska

Swan Point is located in east-central Alaska and is the oldest known archaeological site in the state, as well as the only site in Alaska showing evidence of humans hunting mammoths. Excavations have uncovered evidence of human occupation — such as hearths, tools and animal bones — dating to more than 14,000 years ago.

Based on what has been recovered from the hilltop site, archaeologists think early occupants may have camped there and survived by hunting game in the surrounding wetlands, now known as the Shaw Creek Flats.

Tools discovered at Swan Point include projectile points made of stone and antlers, fragments of an adze for chopping wood or bone, scrapers for skinning and an awl to pierce animal hides. These objects, together with a mammoth tusk, suggest the site may have been a mammoth ivory workshop at some point in prehistory.

3. Cooper's Ferry, Idaho

Cooper's Ferry is a prehistoric settlement at the confluence of Rock Creek and the lower Salmon River in western Idaho. Between 2009 and 2018, archaeologists unearthed 189 artifacts that indicate the site was occupied by humans between 16,000 and 15,000 years ago — including a hearth pit, animal bones, chunks of charcoal, stone tools and flakes of rock shaved off during the toolmaking process.

The site also contained dozens of spearpoints and blades carved out of stone, as well as tooth fragments from an extinct species of horse. The spearpoints are pinkie-sized and unfluted (meaning it's not grooved or ridged), which is typical of a weapon-making tradition known as the western stemmed point tradition, which is distinct from the Clovis point tradition.

4. Paisley Caves, Oregon

The Paisley Caves are a network of eight caves and rock shelters in the Summer Lake Basin, in south-central Oregon. They were carved out by the waters of an ancient lake — Lake Chewaucan — which has since dried up.

Archaeologists first excavated the caves in the late 1930s, revealing fragments of obsidian and bone tools, animal bones, wooden artifacts and baskets.

More recent studies of the caves have also found and analyzed human coprolites, or fossilized feces, which enabled archaeologists to pinpoint human occupation to 14,500 years ago. The age of the fossilized poop, along with the discovery of a serrated bone tool, suggests that pre-Clovis humans occupied the caves. The desiccated poop also made it possible to reconstruct these early occupants' diet, which partly consisted of grasses, large birds and now-extinct giant bison.

5. Page-Ladson, Florida

Page-Ladson is an underwater archaeological site located at the bottom of a 30-foot-deep (9 meters) sinkhole in the Aucilla River, in northern Florida. A former Navy SEAL accidentally discovered the site while scuba diving in the early 1980s, when he spotted bones belonging to an extinct species of proboscidean.

Since then, archaeologists have uncovered stone tools and the remains of other extinct animals — including prehistoric camels, bison and mastodon — that date to 14,550 years ago. A mastodon tusk unearthed at the site bears cut marks that were probably made by humans, although it is unknown whether they butchered the animal or scavenged its remains.

6. Monte Verde II, Chile

Monte Verde II is one of four excavated areas in the Monte Verde archaeological complex, located near Puerto Montt, in the Los Lagos region of southern Chile. A study published earlier this year dates artifacts and structures unearthed at Monte Verde II to 14,550 years ago.

The site contains the ruins of a 60-foot-long (18 m) wood frame that may have supported a tent-like structure, as well as wooden artifacts, stone tools, hearths, food remains and animal bones — including those of half a dozen mastodon. Inside the wood frame, archaeologists discovered hundreds of microscopic flecks of hide tissue embedded in the ground, suggesting the floor was covered with animal skins.

7. White Sands, New Mexico

White Sands National Park,located in southern New Mexico, is the world's largest gypsum dunefield. It contains some of the earliest "unequivocal evidence" of people in the Americas in the form of 23,000-to-21,000-year-old footprints.

These footprints are still visible thanks to a megadrought that lowered the water levels of an ancient and now dried-up lake called Lake Otero, exposing swampy ground that preserved tracks left by humans and animals. The archaeological site contains 61 human tracks, mostly from teenagers and children.

8. Meadowcroft rock shelters, Pennsylvania

The Meadowcroft rock shelters are a National Historic Landmark, located in southwestern Pennsylvania, that contain evidence of human occupation dating to 16,000 years ago.

The site was first discovered in 1955 by a farmer, who found a flint knife, flint flakes and burnt bones in a groundhog hole. Archaeologists didn't excavate Meadowcroft until the 1970s, when they uncovered a wide array of human artifacts, including stone tools, spearpoints and wooden instruments.

Meadowcroft sits atop a yellow sandstone mountain and features a massive rock overhang carved out by the flowing waters of nearby Cross Creek. While being close to this vital source of fresh water, the site would have also kept its early occupants safe from flooding.

9. Debra L. Friedkin Site 

Located about 40 miles (64 kilometers) northwest of Austin, Texas, the Debra L. Friedkin archaeological site held weapons and tools possibly dating to 15,500 years ago.

Archaeologists have unearthed 100,000 artifacts from the site, which sits just north of Buttermilk Creek. These items include blades, scrapers and a circular core from which stone utensils were struck. They also found thousands of chert pieces — scraps and flakes created during tool production — that are at least 13,500 years old.

Some claims about the site are controversial, notably regarding the discovery of 11 spearpoints that archaeologists have estimated could be 15,500 years old. Some experts have raised doubts about the methods used in a 2018 study, which employed optically stimulated luminescence instead of radiocarbon-dating techniques.

10. Bluefish Caves, Canada

The Bluefish Caves are a network of three small cavities overlooking the Bluefish River in Canada's northern Yukon Territory. The site was first discovered during an air survey in 1975, and a 10-year-long excavation project began in 1977.

Archaeologists discovered a small number of tools and 36,000 mammal bones — including from mammoths and extinct horses — some of which bear cut marks and have since been dated to 24,000 years ago. Some experts remain skeptical of those results, as well as of those from a 2021 study that dated several long-debated flakes and fragments of mammoth bone to 28,000 years ago. 

11. Cueva del Chiquihuite, Mexico

The Cueva del Chiquihuite, or Chiquihuite Cave, is situated in the desert mountains of north-central Mexico and contains evidence suggesting there were people in North America as early as 31,500 years ago.

A 2020 study describes thousands of stone fragments, tools and weapons that were found in the cave but were made of a type of limestone sourced elsewhere. Archaeologists also unearthed bits of charcoal dating as far back as 32,000 years ago, but they are unable to tell whether these were made by humans or in natural events.

Experts question the results linked to Chiquihuite Cave, with some arguing that the stone artifacts could have been created by natural processes. The cave also lacks evidence typically associated with human occupation, such as hearths and animal bones with cut marks. Traces of human DNA were found inside the cave, but experts suspect this could be contamination from modern humans.

12. Santa Elina Rock Shelter 

Located in the Mato Grosso state in central Brazil, the Santa Elina rock shelter has exposed unusual evidence of early humans: three pendants made from giant sloth bone.

The discovery places people in South America between 25,000 and 27,000 years ago, while earlier studies describing hundreds of stone artifacts and 1,000 examples of rock art indicated humans were there over 20,000 years ago.

The pendants are made of sloth osteoderms — bony deposits that form the protective armor over the skin of animals such as armadillos — and feature tiny, smooth holes likely drilled and polished by humans. While some experts argue that these holes could not have been created by natural processes, others maintain that the evidence isn't strong enough to prove that humans occupied the site so early.

13. Pedra Furada

Pedra Furada — a large rock shelter located in Serra da Capivara National Park, in Brazil' Piauí state — is one of the most controversial archaeological sites in the Americas.

Excavations in the 1970s and 1980s uncovered stone artifacts and hearths that suggested the site was occupied by humans 32,000 years ago and even as far back as 50,000 years ago.

But a 2022 study found that capuchin monkeys living in the national park are capable of creating objects out of stone that closely resemble those found at Pedra Furada. This finding — combined with the lack of any other trace of human presence, such as hearths or food remains — suggests the site was not populated by humans until much later.

Ancient human skulls, oil lamps and parts of weapons hidden in a cave near Jerusalem are signs the site was used in the Roman era for attempts to speak to the dead — a practice known as necromancy, or "death magic" — according to a new study.

Based on the styles of the artifacts, the researchers think the morbid rituals were carried out at the Te'omim cave, about 20 miles (30 kilometers) west of Jerusalem, between the second and fourth centuries A.D.

According to Boaz Zissu, an archaeologist at Bar-Ilan University in Israel, most of the Jewish people who lived in the region had been eradicated or driven away by the ruling Roman Empire after the Jewish rebellion known as Bar Kokhba revolt, between A.D. 132 and 136. 

The Romans then repopulated the region with people from other parts of their empire — likely from Syria, Anatolia and Egypt, Zissu said.

Related: Biblical scroll found in 'Cave of Horror' in Israel

"A new pagan population arrived in what had formerly been Judea, but was now Syria Palaestina," Zissu told Live Science. "They brought with them new ideas, new customs, and apparently the idea of necromancy."

Zissu is an author, with archaeologist Eitan Klein of the Israel Antiquities Authority, of a new study published July 4 in the journal published in the Harvard Theological Review. It describes the items discovered in the cave: more than 120 oil lamps, ax and spear blades, and three human craniums. 

Speaking with the dead

The vast Te'Omim cave has been visited by people since prehistoric times, and Jewish rebels used it as a hideout from the Romans during the Bar Kokhba revolt.

During the excavations, the researchers discovered three hoards of gold and silver coins from that time. A seam of rare calcite alabaster rock deep within the cave had also been quarried at some point, perhaps to create valuable artworks.

The styles of the oil lamps and some hidden coins suggest the cave became a place for necromancy when new arrivals to the area brought their traditional rituals with them, he said.

Necromancy was considered evil and often banned within the Roman Empire. Still, many ancient cities were near secret "oracle" sites where people believed they could speak to the dead. The cave became one such place.

"There they found perfect conditions," Zissu said. "it's a bit remote, but not so far from the main road; it's deep, but not very deep; and it has a deep shaft at the end that they regarded as a connection to the underworld." 

Ancient rituals

The lamps, human craniums and parts of weapons are lodged in crevices within the huge cave, often so far back that the researchers needed long poles with hooks on the end to retrieve them. Ancient people likely placed them there with poles, Zissu said. 

The crevices are too deep for the oil lamps to have cast much light, and researchers first thought they were artifacts of Chthonic worship — rituals associated with underworld spirits. 

But the craniums, also secreted in the crevices, suggested the real purpose was to try to speak to the dead, who were supposed to be able to foretell the future, Zissu said.

Bones from individuals were sometimes used in an attempt to make contact with that person after their death, and the flickering of flames could be interpreted as their messages from the underworld, the study authors wrote.

"This cave provides important evidence attesting both the diversity of religious practice in the Roman period, and the stark contrast between the religious use of caves by Roman-period polytheists and the earliest Christian cave-churches in the Holy Land," archaeologist Ken Dark of King's College London, who was not involved in the study, told Live Science.

Homo sapiens arrived in Southeast Asia as early as 86,000 years ago, a human shin bone fragment found deep within a cave in Laos reveals.

The finding comes from the cave of Tam Pà Ling, or Cave of the Monkeys, which sits at around 3,840 feet (1,170 meters) above sea level on a mountain in northern Laos. Human bone fragments previously found in the cave were 70,000 years old, making them some of the earliest evidence of humans in this area of the world. This discovery prompted archaeologists to dig deeper. 

The team did just that, finding two new bones, they reported in a study published Tuesday (June 13) in the journal Nature Communications. The bones — fragments of the front of a skull and a shin bone — were likely washed into the Tam Pà Ling cave during a monsoon. Even though the bones were fractured and incomplete, the researchers were able to compare their dimensions and shape with other bones from early humans, finding that they most closely matched Homo sapiens rather than other archaic humans, such as Homo erectus, Neandertals or Denisovans.

The researchers used luminescence dating of nearby sediments and uranium-series dating of mammalian teeth from the same layers to produce an age range for the human remains. Luminescence dating is a technique that measures the last time crystalline materials, such as stones, were exposed to sunlight or heat, while U-series dating is a radiometric technique that, similar to carbon-14 dating, measures the decay of uranium over time into thorium, radium and lead. The skull, they estimated, was up to 73,000 years old, and the shin bone dates back as far as 86,000 years ago.

Related: Some of the 1st ice age humans who ventured into Americas came from China, DNA study suggests

This early date is a remarkable finding, particularly because researchers have long debated the timing of Homo sapiens' arrival in Asia. 

"Little to no anthropological research was done in Laos since the second world war," study lead author Fabrice Demeter, a paleoanthropologist at the University of Copenhagen, told Live Science in an email. Debates about human colonization of Southeast Asia have taken place for decades as researchers have attempted to understand how and when humans crossed straits and seas to eventually end up in Australia. Tam Pà Ling is therefore "a prime place to ask some of these questions about migration, since mainland southeast Asia really sits at the crossroads of East Asia and island SE Asia/Australia." 

While the genetic and stone tool evidence amassed to date strongly supports a single, rapid dispersal of Homo sapiens from Africa some time after 60,000 years ago, studies such as this one are producing evidence for earlier migrations, many of which may have been dead ends.

Michael B.C. Rivera, a biological anthropologist at the University of Hong Kong who was not involved in the study, told Live Science in an email that "perhaps this was a group that dispersed to Southeast Asia and died out before they were able to contribute genes to today's human gene pool. I find the narratives of these 'failed' populations interesting to add, so that we aren't just looking at the 'successful' ones that 'made it'."

No stone tools or other clues about these humans' lifestyles have been found in Tam Pà Ling. But archaeologists working on the prehistory of Asia have long suspected that, even before 65,000 years ago, ancient humans were capable of reaching islands and making sea crossings to populate seemingly remote parts of the world, Rivera pointed out. 

"The claim that H. sapiens made it to this region pre-60,000 years ago is not new," Rivera said, "but it is good to have further confirmation in our attempts to fill in gaps in the archaeological record."

Moray eels that lurk in gloomy, underwater caves appear to be adjusting to the darkness by growing skin over their eyes.

The newly described bean-eyed snake moray (Uropterygius cyamommatus) is the first moray eel species known to inhabit anchialine caves — caves carved into volcanic or limestone rock that are connected to the ocean and whose water levels fluctuate with the tides. During expeditions to Christmas Island, Australia, and Panglao Island in the Philippines, scientists found two specimens that had no visible left eyes, suggesting that the eels may be adapting to their gloomy environment by going blind, one eye at a time.

"Only two specimens from Christmas Island have reduced left eyes and we are not able to know if it is natural or if they just damaged their eyes after being born," said Wen-Chien Huang, a doctoral student of marine biotechnology at the National Sun Yat-sen University in Taiwan and the lead author of a study published March 29 in the journal Raffles Bulletin of Zoology. "But the proportions of their eyes is the smallest that we have ever seen in moray eels, so we speculate it might be the result of adaptation to the aphotic or low-light environment," Huang told Live Science in an email.

Cave explorers first trapped bean-eyed snake morays on Panglao Island in 2001, and several specimens are housed in the Lee Kong Chian Natural History Museum in Singapore, Huang said. But until now, nobody had recognized them as their own species. A 2014 study in the Raffles Bulletin of Zoology incorrectly listed a bean-eyed snake moray that researchers had caught on Christmas Island as Echidna unicolor, a fish known as the unicolor or pale moray.

The two species are both a uniform brown color, but as its name suggests, the bean-eyed snake moray has "tiny bean-shaped eyes" and a longer tail with more vertebrae than the pale moray, the researchers wrote in the new study. Whereas pale morays have been found in coral reefs in the Pacific and Indian oceans, bean-eyed snake morays have only been spotted in a handful of caves on Christmas and Panglao islands.

Related: Does evolution ever go backward? 

Researchers caught the most recent specimens more than 10 years ago with baited traps and pickled them in alcohol to preserve them. It's unclear why or when bean-eyed snake morays retreated into the gloomy cave depths, but the authors of the new study suspect it could be linked to their voracious appetites. "I think one of the reasons they went to inhabit caves is the food source, since there are abundant crustaceans inside the caves," Huang said. The scientists who caught them reported that the "greedy" eels hungrily devoured the bait they used to lure them.

For the new study, Huang and his colleagues analyzed nine specimens collected between 2001 and 2011. Two of them had "a reduced left eye embedded in skin," with no apparent change in the underlying bone structure. The researchers think they may have captured evolution in action and that, in the absence of light, skin encroaching on the eels' eyes could save them the high energetic cost associated with eyesight. 

It is not unusual for cave-dwelling fish to go entirely blind, and many of the nearly 300 fish species that live in caves have done so. A species closely related to the bean-eyed snake moray, the few-vertebrae moray (U. oligospondylus), has similarly reduced eyes and lurks in the shadows between wave-crashed boulders, where it relies on its sense of smell to detect prey.

Scientists are still unsure exactly why skin is growing over the eels' eyes and whether this potential adaptation to their cave habitat is spreading among the population. Due to the low number of preserved specimens, researchers haven't performed genetic and other molecular testing to answer these questions, Huang said. "These are issues that we are interested in, but can only be resolved when more fresh specimens are available."

At least 20,000 years ago, humans living in Europe created striking cave paintings of animals that they paired with curious signs: lines, dots and Y-shaped symbols. These marks, which are well known to researchers, might relate to the seasonal behavior of prey animals, making the signs the first known writing in the history of humankind, a new study claims.

Although Paleolithic cave art is better known for its graceful horses and ghostly handprints, there are thousands of nonfigurative or abstract marks that researchers have begun studying only in the past few decades. In a study published Jan. 5 in the Cambridge Archaeology Journal, a team of scholars suggests that these seemingly abstract dots and lines, when positioned near animal imagery, actually represent a sophisticated writing system that explains early humans' understanding of the mating and birthing seasons of important local species.

Other researchers, however, are not convinced by the study's interpretations of these human-made marks. 

Melanie Chang, a paleoanthropologist at Portland State University who was not involved in the study, told Live Science in an email that she agrees with the researchers' assessment that "Upper Palaeolithic people had the cognitive capacity to write and to keep records of time." However, she cautioned that the researchers' "hypotheses are not well-supported by their results, and they also do not address alternative interpretations of the marks they analyzed."

Related: Back to the Stone Age: 17 key milestones in Paleolithic life

What do the painted marks mean?

Early humans in Europe were hunter-gatherers who ate a lot of meat from species such as horses, deer and bison. When those animals came together seasonally in herds, they would have been vulnerable to slaughter by humans. "It follows that knowledge of the timing of migrations, mating and birthing would be a central concern to Upper Paleolithic behaviour," study first author Bennett Bacon, an independent researcher and furniture conservator based in London, and colleagues wrote in their study. 

Looking at the total number of marks — either dots or lines — found in sequences across hundreds of caves, the researchers discovered that none of the series contained more than 13 marks, consistent with the 13 lunar months in each year. "We hypothesize that sequences are conveying information about their associated animal taxa in units of months," they wrote, noting that spring, "with its obvious signals of the end of winter and corresponding faunal migrations to breeding grounds, would have provided an obvious, if regionally differing, point of origin for the lunar calendar."

The researchers' statistical analysis of more than 800 sequences of marks associated with animals supports their idea — they found strong correlations between the number of marks and the lunar months in which the specific animal is known to mate. 

Taking their hypothesis a step further, Bacon and colleagues focused on a Y-shaped sign that they think refers to a particular event in an animal's life cycle. Similar statistical analysis supports their conclusion that the placement of the Y-shaped sign within a series of marks signals an animal species' birthing season.

"The ability to assign abstract signs to phenomena in the world," they wote, "to record past events and predict future events, was a profound intellectual achievement." 

Writing or proto-writing?

But is this the earliest known writing? Bacon and colleagues demur, suggesting that "it is best described as a proto-writing system, an intermediary step between a simpler notation/convention and full-blown writing."

April Nowell, a Paleolithic archaeologist at the University of Victoria in Canada who was not involved in this study, told Live Science by email that "any study that explores non-figurative signs in more detail is welcome, but I think there are a number of assumptions being made here that have yet to be proven." Nowell questioned the Y sign, in particular. "The majority of animals considered in this study are quadrupeds, and humans normally squat giving birth," she said. "If this sign is supposed to be iconic of the birth process, it is not obvious to me."

Related: One of the oldest written sentences on record blasts hair and beard lice

Chang, the paleoanthropologist who is also an equestrian and horse owner, posed two alternative explanations for the Y sign. In some cases, it could represent the edge of the brachiocephalic muscle, a prominent landmark on a horse's neck. "In other cases," she said, "it is possible that what they recorded as Y's represent what modern horsepeople refer to as 'primitive markings' such as leg bars that are associated with wild-type horse colors, or they may represent hair patterns, or other anatomical features."

Study co-author Robert Kentridge, a professor in the Department of Psychology at Durham University in the U.K., told Live Science in an email that one of the strengths of their study is that they "have formally tested Ben [Bacon's] hypotheses about the meaning of the Y-sign's position in sequences of marks and the lengths of sequences of dots and lines and shown that these do convey meaning, indeed meaning that would be important in the lives of Palaeolithic hunters."

In summarizing their conclusions, Bacon and colleagues wrote that they have "proposed the existence of a notational system associated with an unambiguous animal subject relating to biologically significant events" and that this allows them "for the first time to understand a Palaeolithic notational system in its entirety."

A decade ago, however, Nowell and then-graduate student Genevieve von Petzinger co-created a database of dozens of signs and repeating motifs from more than 200 caves in southern France and Spain. Von Petzinger's thesis detailed patterns of cave wall symbols across time and space in order to better understand what these signs meant for ice age people. "There are at least 32 different recurring signs," Nowell explained. "The authors have chosen to study three of them in a very specific context." 

But the authors defended their decision to focus on the trio.

"It seemed sensible to focus first on the most common markings associated with figurative images," study co-author Paul Pettitt, a professor of archaeology at Durham University, told Live Science in an email. "Simple dots and lines are by far the most common. Of the more elaborate signs, the Y sign is the most common."

The researchers plan to expand on their work. "We are analyzing other signs," Bacon told Live Science in an email. "Rather than searching for the meaning of individual signs, what we are looking for is the linguistic and cognitive bases that underpin the 'writing' system."

Nowell agreed with the study authors that the symbols were likely not randomly chosen and that it is possible the lines and dots represent numbers. Even if the authors are correct, she noted, that leaves 90% of the signs without any known meaning. 

"There is still a lot about graphic communication in the Paleolithic that we do not understand," Nowell said.

Archaeologists in Israel have discovered an "exceptional" cave that ancient people sealed 3,300 years ago, hiding grave goods and possibly human burials within it, just yards from a beach south of Tel Aviv. 

Use of the cave dates to a time when the ancient Egyptians, led by Ramesses II (also spelled Ramses and Rameses) — who reigned from about 1279 B.C. to 1213 B.C. — ruled what is now Israel, the Israel Antiquities Authority (IAA) said in a statement. During the time of Ramesses II, Egypt controlled an empire that stretched from modern-day Sudan to Syria. 

Construction workers operating a mechanical digger in Palmahim Beach National Park discovered the cave when the machine unexpectedly penetrated the roof of the cave. Archaeologists with the IAA were then called to the scene. The team descended a ladder into the dark cave that "appeared to have frozen in time," with carefully laid-out ceramic and bronze goods — artifacts often associated with burial ceremonies, the statement said. Such goods were thought to have helped the deceased in the afterlife.

Related: Ancient 'ritual bath' and elite villa unearthed by Jerusalem's Western Wall

The archaeologists found dozens of pottery vessels, including deep and shallow bowls, some painted with red, as well as chalices (goblets with wide bases), cooking pots, storage jars, and lamps for lighting, the team said in the statement. 

Some of the cave's crafts weren't local. A few of the pottery vessels were manufactured in Syria, Lebanon and Cyprus, Eli Yannai, an archaeologist with the IAA, said in the statement. The team plans to analyze any organic remnants on the vessels to learn more about what may have been inside them. 

The cave also contained bronze arrowheads that, based on their orientation, were likely in a quiver that has since decomposed. 

"This is a once-in-a-lifetime discovery," Yannai said in the statement. "It is extremely rare to come across an 'Indiana Jones film set' — a cave floor laid out with vessels untouched for 3,300 years, since the Late Bronze Age, about the time of the powerful King Rameses II."

He added that because the cave was sealed, much of it was not looted. "The cave may furnish a complete picture of the Late Bronze Age funerary customs," he said.

It's not clear from the IAA statement if any human remains, or if any inscriptions or artifacts that could possibly identify the individual(s), were found in the cave. The IAA has resealed and guarded the cave since its discovery, but it appears that it was recently looted. An investigation is now underway to find out who the looters were, according to the statement. 

Meanwhile, archaeologists are gearing up to analyze the cave's unique preservation. "The news of the discovery of the cave spread like wildfire in the academic world, and we have already received requests from many scholars to take part in the planned archaeological excavation," Eli Eskosido, director-general of the IAA, and Raya Shurky, director of the Israel Nature and Parks Authority, said in the statement.

Originally published on Live Science.

Explorers abseiled, squeezed and crawled their way through Australia's deepest cave system on July 30, boldly going where no cavers had gone before and setting a new cave depth record. 

Cavers from the Southern Tasmanian Caverneers, a speleological organization based in Hobart, Australia, made it through the 1,316-foot-deep (401 meters) cave in Tasmania, an island south of mainland Australia. Stephen Fordyce, who first discovered the cave and organized the expedition, named the cave "Delta Variant" after the delta variant of COVID-19 to remind future cavers of current events, according to a statement released by Southern Tasmanian Caverneers.  

The team spent 14 hours underground, navigating a subterranean system that included a 535-foot-tall (163 m) waterfall. Exploring "the cave was exceptionally strenuous," caver Ben Armstrong, who was part of the exploration, said in the statement. "It was extremely vertical, requiring hundreds of metres to be ascended and descended on ropes."

The bottom of the Delta Variant cave links up with a previously explored system called the Niggly-Growling Swallet cave system. However, the Delta Variant cave entrance is about 13 feet (4 m) higher up on the surface than the previously highest known entrance that connects to that system, so the team's new cave route set a record for the highest entrance to the lowest point, according to the statement. 

While the explorers established a new record for Australia, the deepest known cave in the world is still Veryovkina Cave in Abkhazia, an autonomous republic in northwestern Georgia in the Caucasus, with a depth of 7,257 feet (2,212 m), according to Guinness World Records. 

Related: Cavers discover snakes and waterfalls inside Yemen's infamous 'Well of Hell' in world-first descent

The explorers in Tasmania used lasers and dye-tracing techniques in the cave system to learn the Delta Variant cave's position and how it connects to the Niggly-Growling Swallet system. They explored the cave in stages over a period of 6 months, fixing ropes as they went. 

"It’s been like climbing a mountain in reverse," Southern Tasmanian Caverneers team member Karina Anders said in the statement. "Each trip we have taken as much rope as we can carry, then descended down while exploring side passages, then we go back up. The next trip we bring more rope and go a bit further." 

On the day the team completed their passage, they navigated down their existing ropes to the lowest explored point, and then secured one more rope to descend 115 feet (35 m) down a final shaft that connected Delta Variant cave to the Niggly-Growling Swallet system. After celebrating in party hats, the team returned to the surface via the Niggly-Growling Swallet system, exiting mere feet from the Delta Variant cave entrance.  

"Cavers have been so close for decades!" team member Brendan Moore said in the statement. "However, it is up a short, steep cliff, which no one had ever thought to climb. The actual entrance is hidden by thick scrub and fallen logs. It just shows you what the Tasmanian bush can hide."

Originally published on Live Science.

Leather shoes, clay pipes, a mysterious inscription written in candle soot — these are just a few of the artifacts a group of cavers recently discovered in a centuries-old cobalt mine in Cheshire, England.

The mine, located near Manchester in a village called Alderley Edge, was once a source of cobalt, an element mined for the brilliant blue pigment imbued on pottery and glass. Cobalt mining was a lucrative trade for England in the 19th century. But imports from other countries became cheaper than English cobalt, so this particular mine, owned by Sir John Thomas Stanley in the early 1800s, was abandoned around 1810. 

Members of the Derbyshire Caving Club have been exploring the Alderley Edge mine since the 1970s, leasing access from National Trust, a U.K.-based conservation charity. The caving group recently stumbled upon some personal items left behind in a previously unexplored part of the mine. The discovery was like opening a time capsule.

Related: Ice age mining camp found 'frozen in time' in underwater Mexican cave

"To find a mine in pristine condition, together with such personal objects and inscriptions, is rare," Ed Coghlan, a member of the Derbyshire Caving Club, said in a statement from National Trust. "It is a compelling window into the past and to the last day when the mine workers stopped their activities."

Along with the shoes and pipes, the cavers found a bowl buried in a wall, which might be a sign of superstitious miners thanking the mine for its good ore, according to the statement. One rare finding was an instrument called a windlass, used for lifting and shifting heavy materials.

The fact that the miners left such an important tool behind makes Coghlan suspect that the miners "were told without much warning to collect their tools and move on," he said. 

One particularly mysterious finding was an inscription of the initials "WS," with the date "August 20, 1810" written below.

"Our research so far has not identified who this could be," Coghlan said. "Was it just an individual wanting to say, 'I was here,' or from a visit by a mine manager or estate owner, or could it have been to indicate the last day this mine was in use?"

The cavers found other words and numbers scratched into the mine's walls.

"We found other more basic initials and numbers in what we believe were the 'cribs' or rest areas, as if someone had been learning and practicing their writing," Coghlan said.

Now, you can tour the mine from the comfort of your home. To make the historic discovery more accessible to the public, the Derbyshire Caving Club and the National Trust teamed up with Christians Survey and Inspection Solutions, a company that uses technology to build virtual, 3D models of buildings and underground spaces.

In the Alderley Edge mine, the team used laser scanners, which shoot lasers around the environment. Those laser beams bounce back into the scanner, which calculates the distance each laser beam traveled. Doing that hundreds of times around a space produces a virtual 3D picture. The team also used remotely operated vehicles for the underwater portions of the mine, as well as other 3D imaging techniques.

"The objects found in the mine have been photographed and catalogued and left where they were found, to remain in the underground conditions which have preserved them," Jamie Lund, an archaeologist at National Trust, said in the statement. "It leaves the mine as a time capsule, protecting a place that was once a hive of activity for future generations to explore and enjoy."

Originally published on Live Science.

A team of Chinese scientists has discovered a giant new sinkhole with a forest at its bottom. 

The sinkhole is 630 feet (192 meters) deep, according to the Xinhua news agency, deep enough to just swallow St. Louis' Gateway Arch. A team of speleologists and spelunkers rappelled into the sinkhole on Friday (May 6), discovering that there are three cave entrances in the chasm, as well as ancient trees 131 feet (40 m) tall, stretching their branches toward the sunlight that filters through the sinkhole entrance. 

"This is cool news," said George Veni, the executive director of the National Cave and Karst Research Institute (NCKRI) in the U.S., and an international expert on caves. Veni was not involved in the exploration of the cave, but the organization that was, the Institute of Karst Geology of the China Geological Survey, is NCKRI's sister institute. 

A site for sinkholes

The discovery is no surprise, Veni told Live Science, because southern China is home to karst topography, a landscape prone to dramatic sinkholes and otherworldly caves. Karst landscapes are formed primarily by the dissolution of bedrock, Veni said. Rainwater, which is slightly acidic, picks up carbon dioxide as it runs through the soil, becoming more acidic. It then trickles, rushes and flows through cracks in the bedrock, slowly widening them into tunnels and voids. Over time, if a cave chamber gets large enough, the ceiling can gradually collapse, opening up huge sinkholes. 

Related: Skyscraper-size sinkholes open up on Arctic seafloor

"Because of local differences in geology, climate and other factors, the way karst appears at the surface can be dramatically different," he said. "So in China you have this incredibly visually spectacular karst with enormous sinkholes and giant cave entrances and so forth. In other parts of the world you walk out on the karst and you really don't notice anything. Sinkholes might be quite subdued, only a meter or two in diameter. Cave entrances might be very small, so you have to squeeze your way into them." 

In fact, 25% of the United States is karst or pseudokarst, which features caves carved by factors other than dissolution, such as volcanics or wind, Veni said. About 20% of the world's landmass is made of one of these two cave-rich landscapes. 

The new discovery took place in the Guangxi Zhuang Autonomous Region, near Ping'e village in the county of Leye, according to Xinhua. Guangxi is known for its fabulous karst formations, which range from sinkholes to rock pillars to natural bridges and have earned the region UNESCO world heritage site designation.

Why sinkholes matter

The sinkhole's interior is 1,004 feet (306 m) long and 492 feet (150 m) wide, Zhang Yuanhai, a senior engineer with the Institute of Karst Geology, told Xinhua. The Mandarin word for such enormous sinkholes is "tiankeng," or "heavenly pit," and the bottom of the sinkhole did indeed seem like another world. Chen Lixin, who led the cave expedition team, told Xinhua that the dense undergrowth on the sinkhole floor was as high as a person's shoulders. Karst caves and sinkholes can provide an oasis for life, Veni said.

"I wouldn't be surprised to know that there are species found in these caves that have never been reported or described by science until now," Lixin said. 

In one West Texas cave, Veni said, tropical ferns grow abundantly; the spores of the ferns were apparently carried to the sheltered spot by bats that migrate to South and Central America.

Not only do sinkholes and caves offer refuge for life, they are also a conduit to aquifers, or deep stores of underground water. Karst aquifers provide the sole or primary water source for 700 million people worldwide, Veni said. But they're easily accessed and drained — or polluted. 

"Karst aquifers are the only types of aquifers that you can pollute with solid waste," Veni said. "I've pulled car batteries and car bodies and barrels of God-knows-what and bottles of God-knows-what out of the active cave stream." 

The new discovery brings the number of sinkholes in Leye County to 30, according to Xinhua. The same researchers have previously discovered dozens of sinkholes in Northwest China's Shaanxi province and a cluster of interconnected sinkholes in Guangxi, China Daily reported. 

Originally published on Live Science.

Archaeologists in Alabama have discovered the longest known painting created by early Indigenous Americans, a new study finds. Indigenous Americans crafted this 1,000-year-old record-breaking image — of a 10-foot-long (3 meters) rattlesnake — as well as other paintings, out of mud on the walls and ceiling of a cave, likely to depict spirits of the underworld, the researchers said.

The cave has hundreds of cave paintings and is considered the richest place for Native American cave art in the American Southeast, the researchers said. To investigate its historic art, the team turned to photogrammetry, a technique that involves taking hundreds of digital images in order to build a virtual 3D model. Using this method, the researchers spotted five previously unknown giant cave paintings, known as glyphs. 

"This methodology allows us to create a virtual model of the space that we can manipulate," study first author Jan Simek, a distinguished professor in the Department of Anthropology at the University of Tennessee, told Live Science. "In this particular case, the ceiling of the cave is very close to the floor. So your field of vision is limited by your proximity to the ceiling. We never saw these very large images because we couldn't get back far enough to see them." 

After creating the virtual model, "we could look at it from a greater perspective," he said. "It allows us to see things in a way that we can't in person."

Related: World's oldest cave art, including famous hand stencils, being erased by climate change

The record-setting glyph sports a diamond pattern, indicating that it may depict a diamondback rattlesnake (Crotalus atrox), a creature considered sacred by the Indigenous peoples of the American southeast, the researchers said. These peoples constructed large earthen mounds, used for a variety of purposes, including rituals according to Smithsonian Magazine, and to be closer to the spirits of the upper world, while caves were viewed as the opposite — routes to the underworld. 

"These are special because until now, we have had no large figures from this area," Simek said "And so that changes our perspective on what might be in these caves." For instance, there are similarly large rock art images made by Indigenous peoples in the western United States, although these glyphs are not found in caves, he said.  "It brings the cave art of the southeast into the discussion of other monumental images that we see in different parts of North America," Simek noted.

This cave was first discovered in 1998 and remains unnamed, going by the moniker "19th unnamed cave" in order to protect the discoveries. The cave contains over 3 miles (5 kilometers) of underground passages with the majority of paintings discovered in one large chamber, according to a 1999 study published in the journal Southeastern Archaeology. In continuing to use photogrammetry techniques on the 19th unnamed cave and others, the team hopes to further improve understanding of Indigenous American art. 

The study will be published online Wednesday (May 4) in the journal Antiquity. 

Originally published on Live Science.

Stalactites and stalagmites decorate caves the world over. Stalactites hang down from the ceiling, while stalagmites rise up from the ground. They grow incredibly slowly, and some are so ancient that they predate modern humans, Live Science previously reported. 

These tooth-like rock formations grow when dripping water comes into contact with the cave air, according to the National Park Service website. The water carries dissolved minerals, picked up on its journey from Earth's surface. As it passes through the cave, it leaves tiny traces of those minerals behind, building each stalactite drip by drip.

What shape are stalactites?

Most stalactites are cone-shaped: thick at the top and tapered to a point at the bottom. But some are hollow. Shaped like straws, these stalactites grow when water trickles down their centre. As each drip evaporates, it leaves another shell of minerals at the bottom of the tube. 

Cave straws are incredibly fragile and often crumble at the slightest touch, making them a rare find in well-trodden caves, according to the Journal of Cave and Karst Studies. 

Some straw-shaped stalactites seem to defy gravity. Known as helictites, these structures have twists, spurs, and knobbles that tilt off in all directions. Scientists aren't sure exactly how they form, but they think it might be down to a combination of capillary action and wind, according to the Universities Space Research Association. 

Slight changes in the air currents through a cave, or in the orientation of the crystals in a growing stalactite, can draw tiny water droplets off in new directions. Rather than dripping towards the floor under the force of gravity, they travel sideways or even upwards, leaving their minerals behind as they go.

What do stalactites and stalagmites contain?

Most of the stalactites you see in caves are made from calcium carbonate, according to the Royal Society of Chemistry. It forms two main types of crystals: calcite and aragonite. They have the chemical formula CaCO3.

For this reason, stalactites only tend to appear in caves where the surrounding rocks contain calcium in the form of limestone or dolomite.

Stalactites can also carry traces of other chemicals, which give them different colors and textures. These chemicals include carbonates, sulphides, and even opal.

Limestone caves often contain stalagmites as well as stalactites. These structures grow on the floor, with a thick base and a point that looks up towards the cave ceiling. Some are flat like fried eggs, while others are long and thin, like broomsticks, according to the Encyclopedia of Caves (Third Edition, 2019).

Stalagmites often grow directly beneath stalactites, mopping up any minerals from water droplets that splash down onto the cave floor. However, the two types of cave decoration don't always come in pairs: either one can appear on its own.

Inside a cave

Other cave features

Limestone caves can also contain other kinds of cave decoration. According to the journal Transactions of the Royal Society of South Africa, stalactites and stalagmites are both types of dripstones, named because they form from dripping water. But you might also see flowstones and cave popcorn.

Flowstones appear when water comes down a cave wall in sheets, according to Yorkshire Dales National Park. They look like curtains of stalactites, hanging together like a waterfall frozen in time. Sometimes flowstones contain layers of color from the minerals left behind by the water, earning them the name 'cave bacon', according to the American Geophysical Union (AGU).

Cave popcorn forms where water comes through pores in the rock, forming bumps and lumps that look like berries.

The chemistry of limestone stalactites

Stalactites and stalagmites form when rainwater drips through limestone rock. Along the way, it picks up carbon dioxide, from the air and from any organic matter it passes as it dribbles down, according to the National Park Service. The carbon dioxide reacts with the water to make a weak acid called carbonic acid. This acid can dissolve limestone, reacting with the mineral calcite and drawing it into the water as calcium bicarbonate. 

As the water drips into the cave, it comes into contact with the air again. There, it lets go of the carbon dioxide, and the calcium comes out of solution, forming rock-hard calcite again.

How they grow

Strange stalactites

Did you know, stalagmites and stalactites aren't always found in caves? You can see them under concrete buildings, in lava tubes, and even hanging off the side of your garage in the winter. This is because stalagmites and stalactites aren't always made from limestone.

Ice stalactites are probably the most common type of stalactite. They form when it's cold enough for water to freeze, but sunny enough for it to melt again, according to a 2019 article in the Encyclopaedia of Caves. The melted water trickles towards the ground and re-freezes before it hits the floor.

Scientists from the University of Cambridge and the University of Arizona used photographs, maths, and physics to work out why icicles are pointy. They noticed that, as the water trickles down, it blends together to form a sheet. That sheet gives off heat, making a warm pocket of air around the icicle. The warm air rises up, which means that water freezes faster at the bottom of the icicle, making them grow long and thin at the tip.

Another kind of stalactite you might see in your everyday life is a concrete stalactite, according to the Royal Society of Chemistry. You can find them in car parks and even on the pipes in your home. Concrete contains calcium oxide, which dissolves when alkaline liquid passes through it. When that liquid hits the air, the calcium comes out of solution, forming a hard substance called calthemite. If the drips come fast enough, calthemite stalagmites can start to form too.

Other strange stalactites are a bit harder to find. Lava stalactites form inside tunnels called lava tubes, which carry molten rock beneath the Earth, according to the International Journal of Speleology. When the roof of a lava tube starts to cool, it gets a skin, a bit like a bowl of custard. Underneath, hot gases keep expanding, pushing on the skin and stretching it out to form hollow tubes that harden into solid rock.

Additional resources

As well as providing stunning features, the geology of caves can teach us about Earth’s climate. You can read about these clues at the NOAA's National Center for Environmental Information. To find out more about underwater stalactites, explore the research carried out by Heidelberg University.

Bibliography

Journal of Cave and Karst Studies of the National Speleological Society (2005). https://caves.org/pub/journal/PDF/V67/cave_67-01-fullr.pdf

"Analysis and optimization of process parameters for in vitro biomineralization of CaCO3 by Klebsiella pneumoniae, isolated from a stalactite from the Sahastradhara cave". Royal Society of Chemistry (2020). https://pubs.rsc.org/en/content/articlehtml/2020/ra/d0ra00090f

Encyclopedia of Caves, Third Edition, (2019).  https://www.sciencedirect.com/topics/earth-and-planetary-sciences/stalagmite

The Geology of the Makapan and other Caves. Transactions of the Royal Society of South Africa (1951). https://www.tandfonline.com/doi/abs/10.1080/00359195109519881?journalCode=ttrs20

The origin of tubular lava stalactites and other related forms. International Journal of Speleology (1998). https://digitalcommons.usf.edu/ijs/vol27/iss1/14/

Archaeologists in Italy have unearthed the earliest known female infant burial in Europe, the 10,000-year-old grave of a newborn baby. The young girl, who researchers have nicknamed "Neve," was buried with a rich array of grave goods, such as shell beads and pendants.

The discovery sheds light on the cultural beliefs and social status of post-ice age humans in Europe — a period in human prehistory from which recorded burials are remarkably rare. The care given to the infant upon her burial suggests that even the tiniest members of this ancient society were considered "people," the researchers argue. 

Archaeologists discovered the burial  in 2017 during excavations at a cave site known as Arma Veirana in the foothills of the Ligurian Alps of northwestern Italy. Previous excavations at the cave have unearthed artifacts associated with Neanderthals, who occupied the cave 50,000 years ago. So the discovery of the child burial, which was 40,000 years younger, was a surprise. 

Related: Back to the Stone Age: 17 key milestones in Paleolithic life

This time period, known as the Mesolithic, occurred at the end of the last great ice age in Europe, before the widespread adoption of agriculture. Humans at that time lived in hunting and gathering groups, and roamed the plains of Europe using skins for clothes and wood and stone for tools. 

The excavators unearthed the burial in the deeper recesses of the cave. They had excavated near the cave's mouth during earlier excavations and had moved deeper into the cave to learn more about its occupation history and geologic layers. The team soon began to uncover perforated shell beads that dated to the post-Neanderthal period. A few days later, one of the excavators uncovered the fragment of a human skull. As they continued to dig, they found a deliberately interred human child. 

Subsequent DNA analyses revealed that the child belonged to a lineage of European women known as the U5b2b haplogroup. The U5 haplogroup is the predominant maternal lineage found in European Mesolithic hunter-gatherers, and it likely originated between 17,000 and 12,000 years ago. Other analyses showed that she died some 40 to 50 days after birth and that she had experienced physiological stress that disrupted the growth of her at two separate time points — 47 days and 28 days before her birth. 

The find is especially important because it sheds light on the cultural beliefs of those living during this little-known period. The child was buried with over 60 perforated shell beads, 4 shell pendants and the talon of an eagle-owl. The beads required great care to make and maintain, suggesting that the ornaments were passed down to the child from group members. It also indicates that even the youngest members of the hunting and gathering group were invested with personhood and thought to have an individual self, moral agency and eligibility for group membership, the researchers suggested.

"The Mesolithic is particularly interesting," study co-author Carey Orr, a paleoanthropologist and anatomist at the University of Colorado School of Medicine, said in a statement. "It followed the end of the final ice age and represents the last period in Europe when hunting and gathering was the primary way of making a living. So, it's a really important time period for understanding human prehistory."

The burial was described in a study published Dec. 14 in the journal Scientific Reports.

Originally published on Live Science.

A winding lava-tube cavern in northern Saudi Arabia was home to hyenas for millennia, and they left behind plenty of gruesome evidence of past meals. The floor of the cave system was covered in deep piles of gnawed bones — some of which belonged to people. 

Hyenas often scavenge their meals, so they probably didn't kill their human prey, but rather, dug up cadavers from nearby burials and devoured them in this underground den, scientists recently reported.

Other researchers described the western part of the lava tube site in 2009 as the "Wolf Den," because they suspected that wolves were responsible for the vast collection of bones. However, new analysis of the bone piles, coprolites (preserved feces) and individual bones told a different story. Scientists now suspect that the den belonged to striped hyenas (Hyaena hyaena), which fed on a variety of animals — including humans — in that location from at least 4,500 years ago until as recently as 150 years ago. 

Related: 5 reasons hyenas like Harley Quinn's 'Bruce' are amazing

Lava tubes are underground passageways carved by rivers of lava that can reach temperatures exceeding 2,000 degrees Fahrenheit (1,090 degrees Celsius), according to the National Park Service Hawai'i. When lava flows are trapped in pools by rock walls, they can heat up and begin eating through the crust below, creating subterranean channels and networks. Once the flows subside or get diverted, tunnels that are left behind can extend as long as 40 miles (65 kilometers) and measure several dozen feet wide, NPS Hawai'i says. 

For the new study, the researchers investigated part of Saudi Arabia's Umm Jirsan lava tube — the longest such network in the country. Located in the Harrat Khaybar lava field, this tube is made up of three passages separated by two collapsed walls of rock, scientists reported July 20 in the journal Archaeological and Anthropological Sciences. Umm Jirsan measures about 4,900 feet (1,500 m) long, with a passage height of about 26 to 29 feet (8 to 12 m).

The scientists focused on the lava tube's western passage, which contained "an extremely dense accumulation of bones," the authors wrote. They examined more than 1,900 bones, identifying 40 individual creatures. Most of the bones belonged to donkeys, followed by caprines — a type of goat — gazelles, camels and wolves or dogs. The scientists identified two human skull fragments at this location, "and a number of others [human bones] were discovered in other parts of the Umm Jirsan system," they wrote in the study. 

Other sites from elsewhere in the Middle East and Africa contain similar bone hoards that are thought to span thousands of years, but the data from those locations isn't as complete as the evidence from Umm Jirsan, raising questions about how long those dens were actually in use, said lead study author Mathew Stewart, a postdoctoral researcher in the Department of Archaeology at the Max Planck Institute for the Science of Human History in Jena, Germany.

Patterns of wear on the bones from chewing, licking and partial digestion matched marks left on bones by modern hyenas, and the enormous quantities of discarded bones also hinted at hyenas' habits, according to the study. Striped hyenas are also known for denning deep in cave networks. And while wolves tend to do most of their eating at the site of a kill, hyenas avidly hoard meaty bones in their dens; their powerful neck and jaw muscles enable them to carry heavy carcasses for great distances and crack large bones to reach the marrow inside, the authors reported.

"Striped hyena[s] were the most likely accumulator of bones at Umm Jirsan," Stewart told Live Science in an email. 

But even if those hyenas were dining on human flesh, that doesn't necessarily mean that they were hunting people, Stewart added.

"While predation of humans is possible — and some instances of predation on modern humans [have] been noted — the human remains at Umm Jirsan are likely due to striped hyena scavenging from human grave sites," Stewart said.

In addition to providing a glimpse of hyena habits spanning thousands of years, Umm Jirsan also preserves a broader snapshot of biodiversity in a region "where bone and fossil preservation is otherwise exceptionally poor," Stewart said. "Sites like these may hold potential keys to understanding the environments and ecologies of the past in arid regions like Arabia."

Originally published on Live Science.

Cave explorers from Oman have become the first individuals to descend to the bottom of the 367-foot (112 meters) deep "Well of Hell" sinkhole in Yemen, which many local people believe is a genie-infested gateway to the underworld, according to news reports.

The natural sinkhole, officially known as the Well of Barhout, has an eerily circular entrance that spans 98 feet (30 m) in diameter and is located in the middle of the desert in al-Mahra province in eastern Yemen, close to the border with Oman. Amateur cave explorers have entered the sinkhole before, but until now nobody was known to have made it all the way to the bottom.

Last week, a team of 10 explorers from the Omani Caves Exploration Team (OCET) explored the Well of Barhout using a pulley system that lowered eight of the members to the bottom while the remaining two stayed at the top. A small crowd of intrepid spectators gathered to watch the event, despite local fears surrounding the sinkhole. A video of the explorers descending into the cave was shared by the BBC.

Related: The 7 longest caves in the world

"Passion drove us to do this," Mohammed al-Kindi, a geology professor at the German University of Technology in Oman who was part of the OCET team, told French news agency AFP. "And we felt that this is something that will reveal a new wonder and part of Yemeni history."

The explorers reported finding waterfalls, snakes, dead animals, stalagmites and cave pearls, but unsurprisingly they did not find any genies or a doorway into hell. 

Local myths 

The exact age of the Well of Barhout is currently unknown, but it is likely millions of years old, according to AFP. 

Many local myths have sprung up to explain the sinkhole, most of which describe it as a prison for jinn, or genies, which causes bad luck as a result. Some people also believe that if they get too close, the sinkhole can pull people inside; others claim that the gaping hole is a supervolcano capable of destroying the Earth, according to AFP, although there is no scientific evidence to back this up. 

In the past, people have also reported a foul smell rising from the large hole, something that spurred stories about it being a gateway to hell, leading to its nickname.

However, in reality, the Well of Barhout is a fairly typical sinkhole.

How sinkholes form

"There are different types of sinkholes," Philip van Beynen, a sinkhole expert at the University of South Florida who was not involved in the exploration, told Live Science. "The most common are collapse and subsidence sinkholes."

Related: See wild photos of gaping sinkholes

Collapse sinkholes form when voids in the bedrock below the surface expand so much that the roof above is no longer supported, and the rock and overlying sediment suddenly collapse into the cave. Subsidence sinkholes occur when surface sediments slowly trickle down into small voids below the ground until a depression or sinkhole forms, van Beynen said.

Both rely on a special type of landscape, known as karst, characterized by carbonate bedrock like limestone and dolomite, which is soluble in water and leads to caves, springs and sinkholes, van Beynen said.

Unfortunately, it is hard to tell exactly how or when sinkholes form, he added. "Unless it occurs when people live at the site and record the event, then it's almost impossible."

Exploring the cave 

As the OCET team descended into the sinkhole, they arrived on an uneven and jagged floor covered in stalagmites, some of which reached 30 feet (9 m) tall, according to Omani newspaper Muscat Daily. Some parts of the floor were also covered in cave pearls, which are also a type of speleothems — structures in caves, such as stalagmites and stalactites, that form from the gradual build-up of minerals, such as calcium carbonate, from dripping water.

"They [cave pearls] form from dripping or flowing water as concentric layers of mineral, usually around some kind of a nucleus," Leslie Melim, a geologist at Western Illinois University who specializes in cave pearls, told Live Science. "Practically, anything can act as a nucleus, whatever is present in the cave or mine. Since the nucleus is loose, minerals can grow entirely around the grain, which starts a pearl forming."

Cave pearls are uncommon and can grow only on parts of a cave floor that are completely flat so that the nucleus doesn't move around, Melim said. 

From inside the sinkhole, the team also discovered that water emerges from several holes in the cave walls at around 213 feet (65 m) below the surface, creating small waterfalls, according to Muscat Daily. This provides the dripping water needed  for a the speleothems, stalagmites and cave pearls, to form, Melim said.

The explorers also reported seeing snakes, frogs and beetles inside the cave system, as well as several dead animals, mainly birds, that appeared to have fallen inside the pit. The rotting corpses could have caused the stench reported by locals, but "there was no overwhelming bad smell" inside the sinkhole, al-Kindi told AFP.

The team took samples that may also reveal further information on the sinkhole and how it formed. "We collected samples of water, rocks, soil and some dead animals but have yet to have them analyzed," al-Kindi told AFP.

A final report on the exploration of the Well of Barhout is expected in the coming weeks.

Originally published on Live Science.

The world's longest known cave system just set a new record after surveyors spent hours mapping an additional 8 miles (13 kilometers) of the passageways at Mammoth Cave National Park in Kentucky.

The corridors at Mammoth Cave now measure a whopping 420 miles (676 km) in length, according to the National Park Service (NPS). That's about the distance between New York City and Raleigh, North Carolina.

Mapping the cave system was a huge undertaking, carried out by volunteers at the Cave Research Foundation (CRF), a Kentucky-based nonprofit group, and other locals, including those from the Central Kentucky Karst Coalition.

"Many of the cave trips are long and arduous, involving climbing, vertical exposure, squeezes, crawlways, water and mud," Karen Willmes, the eastern operations manager with CRF, said in an NPS statement released on Sept. 11. "After the trip, cartographers turn the data collected on the cave trip into a map. Other volunteers provide surface support. It's a first-rate effort for a world-class cave, and we're proud to be a part of it."

Related: Photos: Amazing caves around the world 

This isn't the first time that the Mammoth Cave system has "grown." It entered the record books in 1969, with a total of 65 miles (105 km) of documented passageways. Then, during a 14-hour survey in September 1972, CRF cavers discovered a connection between the Mammoth Cave system and the Flint Ridge system, bringing Mammoth Cave's total known distance to 144 miles (232 km). 

Since then, additional CRF surveys have added mileage to the Mammoth Cave system, including the discovery of connections between it and smaller caves, such as Proctor Cave, Roppel Cave and Morrison Cave, according to the NPS statement. 

"When it comes to discoveries in Mammoth Cave, there truly is no end in sight!" officials at Mammoth Cave National Park posted on the park's Facebook page.

The Mammoth Cave system is an enormous labyrinth that formed through limestone erosion, a phenomenon scientifically known as karst topography, which is also seen in other soluble rocks, such as marble and gypsum. Karst topography occurs when water from rain and rivers from the ground's surface seep underground through cracks, fractures and holes and then travel far underground, slowly dissolving and shaping the soft underground bedrock into caves and other geologic features, according to a blog post by the U.S. Department of the Interior and the NPS.

Every year, more than 2 million people visit the cave system, which is home to 130 wildlife species, including 14 species of troglobites, or animals that exclusively live in caves, such as the eyeless southern cavefish (Typhlichthys subterraneus).

Mammoth Cave National Park is one of only 13 natural U.S. sites recognized as a World Heritage Site by the United Nations, which praises the caves for their "long passages with huge chambers, vertical shafts, stalagmites and stalactites, splendid forms of beautiful gypsum flowers, delicate gypsum needles [and] rare mirabilite flowers… No other known cave system in the world offers a greater variety of sulfate minerals." (Here's a list of the other natural World Heritage Sites in the U.S.)

Meanwhile, the longest underwater cave system in the world sits in the Mexican state of Quintana Roo on the Yucatán Peninsula. In 2018, researchers with the Great Maya Aquifer announced that two previously known underwater cave systems were connected, forming the larger Sac Actun system, which now measures 215 miles (347 km) long, Live Science previously reported.

Originally published on Live Science.

The world's rarest seals have been caught on camera in secret breeding caves in northern Cyprus. The new breeding sites provide hope for a struggling species, but the caves are now in need of protection.

Mediterranean monk seals (Monachus monachus) are the most endangered of all the pinniped species — a group that includes seals, sea lions, sea otters and walruses — with just 700 individuals left in the wild, according to the International Union for Conservation of Nature Red List of endangered species. A large number of those seals live in and around Cyprus.

Due to human pressures, such as bycatch and tourism, the monk seals have been forced to raise their pups inside cave systems, rather than their usual open beaches, on the island. A new study using camera traps, carried out by researchers from the University of Exeter in the U.K. and the Society for the Protection of Turtles (SPOT) in Cyprus, has revealed several previously unknown breeding caves in northern Cyprus, the first to be found along the north coast of the island.

Related: Photos: Stunning shots of the natural world and wildlife

"The study has found regular breeding, identified important sites and shown some seals are using the site year after year," lead author Damla Beton, a marine biologist at SPOT, said in a video about the study. "It is very important to make sure that these sites are protected."

Forced into caves 

For centuries fishers across the Mediterranean have killed monk seals for a variety of reasons: the seals damage their fishing gear; they compete for the same fish prey; and the seal skin can be sold on the black market for its unsubstantiated health benefits. More recently, fishers have captured the seals for use in the aquarium trade as performers; meanwhile, the pinnipeds have lost habitat to the tourism industry, according to the Seal Conservation Society in the U.K..

Historically, monk seals would have used beaches as places to rest and raise their pups like every other species of seal. However, because of historic hunting and a lack of undistrubed beaches, they have been forced to start using alternative locations.

"They need caves to breed in and raise their pups out of sight of humans," Beton said. 

Although the caves keep the monk seals and their pups safe, only a small number of caves monitored are suitable for pupping, according to the researchers.

In 2007, a survey found 39 breeding caves on the south coast of Cyprus (although several have since been destroyed), according to the researchers. However, despite frequently being seen in the north of the island, there was no evidence the seals were breeding there. 

"It has long been known that they use north Cyprus coasts, but in 2013 we observed a pup in Alagadi [in north Cyprus], which confirmed them breeding," Beton said in the video. "In 2016, we started the first breeding surveys using camera traps placed in caves."

The research continued until 2019 and revealed that, out of the eight caves monitored, the seals were using three for breeding. At one of the caves, a single seal also managed to successfully raise pups three years in a row, suggesting that these caves are high-quality breeding sites and could play an important role in keeping population numbers up. 

Protecting the remaining monk seals 

The discovery of new monk seal breeding sites is welcome news to conservationists, but they say now it is important to protect these sites for the future.

"This area of coastline is being developed rapidly, especially for construction of hotels," Robin Snape, an environmental biologist at the University of Exeter, said in a statement. "The main breeding site we identify in this study currently has no protected status, and we are working with local authorities to try to change this."

However, losing their breeding sites is not the only challenge facing the monk seals. "Another major threat to monk seals in this area is bycatch," Beton said in the statement. This means they get accidentally caught in a fisher's nets, which often causes them to drown before they can be freed.

"We need to work with fishers to secure food sources for monk seals and prevent bycatch, especially around these caves," Beton said in the video.

The study was published online March 2 in Oryx - the International Journal of Conservation.

Originally published on Live Science.

Following her death about 5,600 years ago, a Stone Age woman's skull took an unexpected journey when mud and water washed it away from her burial site and into the craggy rocks of a steep cave in what is now Italy, a new study finds.

When archaeologists found the skull, its resting spot in the cave shaft was so hard to reach that only one archaeologist, using rock climbing equipment, could squeeze into the space to recover it. During a later analysis, the researchers found that the skull was very scratched up; at first, they couldn't make heads or tails of what had happened to the ancient woman. 

But, after determining which of the skull's lesions were likely caused by humans and which were likely incurred as the skull tumbled against various rocks, the researchers came up with a possible scenario. Once this woman died, people in her community likely dismembered her corpse — a funeral practice performed at other burials from this time period and region. After people separated the woman's skull from the rest of her body, environmental forces swept it away into the cave, the researchers suggested. 

Related: Back to the Stone Age: 17 key milestones in Paleolithic life 

Archaeologists discovered the lone skull in 2015 in northern Italy's Marcel Loubens cave. Caves are common sites for ancient burials, but archaeologists couldn't find any other human remains there, even when they returned in 2017 with climbing equipment to retrieve the skull. 

A CT (computed tomography) scan and analysis of the skull itself revealed that the woman was between the ages of 24 and 35 when she died, while radiocarbon dating indicated that she lived between 3630 and 3380 B.C., during the New Stone Age, or Neolithic period. To put that into perspective, this woman lived just before Ötzi the Iceman, whose mummified remains date to 3300 B.C. and were also found in northern Italy.

What happened?

Several traumatic lesions on the woman's skull helped the researchers piece together her strange story. One dent — which showed signs of healing, meaning it was incurred when she was alive — may have been made forcefully with tools, as there were parallel grooves below it, the researchers said. Perhaps this woman had undergone cranial surgery, such as trepanation — a technique employed during the Neolithic and later in which holes are made in the skull, they said. A smudge of red ocher pigment found on this dent may have been placed there for therapeutic or symbolic reasons, the team noted.

Other lesions indicated that the soft tissues on her skull had been cut and scraped off after she died, as these lesions showed no signs of healing, the researchers said. This practice has been documented at other Neolithic burials in Italy; for instance, at Re Tiberio Cave in northern Italy, the long arm and leg bones of up to 17 Neolithic human skeletons were arranged in order, and their heads were missing — clues that these people's body parts might have been separated and rearranged after death. Other Neolithic remains found at nearby caves also show evidence of cranial scrape marks that were made after those people died, the researchers said.

Life during the Neolithic was challenging, so it's no surprise that the woman wasn't in the best health. Tiny holes on top of her skull may be related to inflammation, possibly from chronic anemia (iron or vitamin B12 deficiency), the researchers said. The woman also had two dense, ivory-like spots on her skull, which were likely benign tumors. Even her tooth enamel was underdeveloped, suggesting that she had health problems when her permanent teeth were developing in early childhood. She also had several cavities, possibly due to a diet high in carbohydrates, the researchers said.

Related: Images: A new face for Ötzi the Iceman mummy

Rocky tumble

Other damage and encrusted sediment on the woman's skull told another story — essentially, that natural forces moved the woman's cranium after her burial. After the woman was laid to rest, the dismembered skull rolled away, probably with water and mud that was flowing downhill toward a sinkhole. 

"After a long and bumpy ride, [the skull] accidentally ended up in the cave," the researchers said in a statement. Over time, the sinkhole's geological activity created a cave, where the skull sat for 5,600 years until it was discovered by modern archaeologists.

The skull's resting spot is "unusual," but "the authors are able to provide a plausible scenario how the skull ended up in this cave," said Thomas Terberger, an archaeologist at the Lower Saxony State Office for Cultural Heritage, in Hannover, Germany, who wasn't involved in the study. But the origin of some of the skull's lesions is still murky, he said.

"I have the feeling the authors themselves, who did a very good job, are not 100% sure about this," Terberger told Live Science in an email. "It is not always easy to distinguish between striations (caused by transport in the sediment/rocky ground) and cut marks."

Even though this skull represents just one individual, "case studies like this are important to show the huge variety of postmortem episodes that can actually happen to skeletal remains, initiated by natural or anthropogenic [human-caused] factors," Christian Meyer, lead researcher at the OsteoArchaeological Research Center in Germany, who wasn't involved in the study, told Live Science in an email.

The study was published online Wednesday (March 3) in the journal PLOS One.

Originally published on Live Science.

A venomous centipede is the top predator in a pitch-black poison cave that hasn't seen daylight in more than 5.5 million years. 

Located in Romania, Movile Cave is over 65 feet (20 meters) below the surface, and its warm, moist air is low in oxygen and thick with toxic gasses, which feed chemosynthetic bacteria. Yet despite these seemingly hellish conditions, the cave hosts a diverse community of spiders, scorpions and other arthropods, along with snails, earthworms and cave leeches. 

Now, scientists have added a newfound species to the list: a centipede that they named Cryptops speleorex, "which can be translated to the 'king of the cave,'" researchers said in a statement.

Related: Creepy crawlies & flying wonders: Incredible cave creatures

The "king" measures no more than 2 inches (52 millimeters) long, but it is the largest of the cave's predatory arthropods "by far," ruling its domain with deadly bites, the researchers reported in a new study, published online Dec. 16 in the journal ZooKeys.

Since Movile Cave's discovery in 1986, few people have explored its dangerous depths. The air is high in hydrogen sulfide, methane, ammonia and carbon dioxide, and oxygen is in short supply, with levels in some parts of the cavern as low as 7% (the average oxygen level aboveground is typically about 21%). Though the air temperature is a relatively comfortable 70 degrees Fahrenheit (21 degrees Celsius), relative humidity is 100% and air circulation is close to zero, the scientists wrote.

Entering the cave is fraught with danger, leading explorers down a long, narrow shaft and through winding limestone tunnels that finally open into a main cavern with a lake, the BBC reported in 2015. Exploring the rest of the cave system requires diving into the lake and navigating through tight passageways underwater — in complete darkness — that feed into mini-caves called airbells, according to the BBC.

In this dark, isolated and poisoned kingdom live 51 species of invertebrates, 34 of which are found only in Movile Cave, the study authors reported. The newly described cave king, C. speleorex, has a brownish-yellow body with pale yellow antennae, and its yellow legs are studded with 13 to 17 "saw teeth." As the biggest invertebrate predator in the cave ecosystem, this centipede stands at the top of the food chain; other researchers previously observed C. speleorex snacking on primitive insects, spiders, beetles and isopods (shrimp-like crustaceans).

The centipede closely resembled the centipede C. anomalans, which is found worldwide, and was most similar to C. anomalans populations in Romania and Serbia. However, certain features in the newfound species, such as longer antennae and more saw teeth on its legs, indicated that it possessed unique sensory specializations to help it survive in the lightless cave.

The researchers' findings "revealed that the Movile centipede is morphologically and genetically different" from its terrestrial centipede cousins, "evolving from its closest surface-dwelling relative over the course of millions of years into an entirely new taxon that is better adapted to life in the never-ending darkness," the scientists said in the statement.

Originally published on Live Science.

Just before going into a hallucinogenic trance, Indigenous Californians who had gathered in a cave likely looked up toward the rocky ceiling, where a pinwheel and big-eyed moth were painted in red. 

This mysterious "pinwheel," is likely a depiction of the delicate, white flower of Datura wrightii, a powerful hallucinogen that the Chumash people took not only for ceremonial purposes but also for medicinal and supernatural ones, according to a new study. The moth is likely a species of hawk moth, known for its "loopy" intoxicated flight after slurping up Datura's nectar, the researchers said.

Chewed globs that humans stuck to the cave's ceiling provided more evidence of these ancient trips; these up to 400-year-old lumps, known as quids, contained the mind-altering drugs scopolamine and atropine, which are found in Datura, the researchers said.

Related: Trippy tales: The history of 8 hallucinogens

The finding marks "the first clear evidence for the ingestion of hallucinogens at a rock art site, in this case, from Pinwheel Cave, California," the researchers wrote in the study, published online today (Nov. 23) in the journal Proceedings of the National Academy of Sciences.

The artists probably weren't high when they drew the rock art, however. "It's extremely unlikely because of the debilitating effects of Datura," study lead researcher David Robinson, a reader in archaeology at the University of Central Lancashire in England, told Live Science. Rather, just like religious artwork and objects at a church, these rock paintings were likely "setting the scene," and helping people about to go into a trance understand the flower's power and the shared tradition of taking the hallucinogen in that particular cave, he said.

Coming of age ceremony

Archaeologists first learned about the rock paintings in 1999, when workers at Wild Wolves Preserve, a nature preserve about 90 miles (145 kilometers) northeast of Santa Barbara, found a pinwheel and insect painted with ochre, a reddish mineral used in cave art around the world. 

At first glance, the 4-inch by 7-inch (10.5 by 17 centimeters) pinwheel drawing doesn't look much like a Datura flower, but any botanist would tell you otherwise. Datura, also known as jimsonweed and angel trumpet, unfurls at dusk and dawn when insects pollinate it, but during the heat of the day it twists up. It's possible this cave painting features an "opening Datura flower," the researchers wrote in the study.

Researchers already knew that the Chumash people used Datura for ceremonies and in everyday life, according to historic descriptions from missionaries and anthropological work. Historians think Datura was used to "gain supernatural power for doctoring, to counteract negative supernatural events, to ward off ghosts, and to see the future or find lost objects, but, most especially, as a medicine for a variety of ailments," the researchers wrote in the study. It was also put in a tea called toloache for a coming-of-age ceremony for boys, and sometimes girls, who took the trance-inducing plant to mark their entrance into adulthood, Robinson said. 

However, Robinson and his colleagues needed more evidence than cave art to suggest that Indigenous people used this site for Datura ceremonies. So, the team investigated the mysterious quids stuffed into the ceiling's crevices. Quids, known from other archaeological sites in the American Southwest, are plants usually chewed for their nutrients or stimulants, including yucca, agave or tobacco. In this case, 3D digital microscopy revealed that the quids in Pinwheel Cave were also likely chewed. "[The quids] consistently had indentations that we would expect from molars, so it appears that they had inserted it into their mouth and chewed," Robinson said.

Related: Photos: Rock art may depict one of first volcanic eruptions that humans ever drew

The quid fibers were also matted together, and "you would expect that to occur through some sort of moisture that would make it adhere, such as human saliva," he said. Meanwhile, a chemical analysis revealed the presence of the Datura's hallucinogenic compounds atropine and scopolamine, and a scanning electron microscope analysis further identified the quids as Datura, although one quid was made of yucca. 

"Each quid appears therefore to have been a single 'dose,' inserted into the mouth and chewed/sucked in order to extract the hallucinogenic [compounds]," the researchers wrote in the study. After the quids were chewed, they were apparently stuck into the ceiling, like a piece of chewed gum.

Radiocarbon dating shows the cave was used on and off again from about 1600 to the late 1800s. And Indigenous people used the cave for many other purposes: The archaeologists also found projectile points and an arrow shaft straightener — indicating the cave may have served as a place for preparing hunting tools. Likewise, ground seeds and animal remains suggest the cave was used for food preparation, storage and communal meals.

The new discovery helps dismantle the myth of the lone shaman, going into a cave by himself to have a mystical experience, Robinson said.

"This is a community site," Robinson said. He added that today's Tejon Indian Tribe, composed of the descendants of the Chumash, Yokuts and Kitanemuk peoples, use the site today.

Indigenous people around the world, including ancient cultures in Siberia, North America and South America, are known to have taken mind-altering substances, said Patrick McGovern, the scientific director of the Biomolecular Archaeology Project at the Penn Museum in Philadelphia, who was not involved in the study. And this study used cutting-edge techniques "to elucidate an important biocultural issue — the use of hallucinogens by peoples of the Americas," McGovern told Live Science in an email.

Originally published on Live Science.

At the end of the last ice age, Indigenous miners in what is now the Yucatan Peninsula, Mexico risked life and limb — venturing into pitch dark caves illuminated only by fire — to extract a prized mineral, a new study finds.

That mineral wasn't gold or diamonds, but red ochre, a valuable crayon-like pigment that prehistoric people used for both ritualistic and everyday activities, including rock paintings, burials and possibly even insect repellent. 

No one knows, however, how the Indigenous people of the Yucatan Peninsula used ochre. After Indigenous people mined the caves, between about 12,000 and 10,000 years ago, the caves flooded as the ice age ended and sea levels rose. But the still water in the caves preserved the miners' camps — even the charred remains of their fires — allowing archaeologists to see exactly how the mineral was extracted.

Related: Photos: Oldest known drawing was made with a red crayon

The site is basically "a time capsule underwater," study lead author Brandi MacDonald, an assistant research professor in the Archaeometry Laboratory at the University of Missouri Research Reactor, told Live Science. "It's a really rare opportunity to get to see something with such amazing preservation."

Cave divers discovered the ancient mining camps in April 2017, after study co-author Fred Devos, a diver with the Aquifer System Research Center of Quintana Roo (CINDAQ), a local conservation group, discovered a previously undocumented passageway in the Sagitario cave system. 

The underwater passageway led the divers to a spectacular array of ice age mining artifacts, including tools, mining pits and stone markers, likely left so the miners wouldn't get lost in the dark labyrinth. After inviting study co-researcher Eduard Reinhardt, geoarchaeologist at McMaster University in Canada, to join them on a dive, the groups' understanding of the cave's history clicked into place, said study co-author and CINDAQ founder Samuel Meacham, who accompanied Devos on the first dive through the mysterious passageway.

Meacham and his colleagues have spent the past 25 years diving in the cave systems in Quintana Roo. Scientists know that these caves were explored almost as soon as humans inhabited the region, because divers have recovered human skeletons from several of the caves, including at Hoyo Negro and Chan Hol Cave, said Mark Hubbe, a professor of anthropology at The Ohio State University, who was not involved in the study. But some of the findings defied explanation.

"Over the years, we have seen these anomalous weird things within caves that we couldn't quite explain — rocks out of place, rocks stacked on top of each other, things that just didn't seem natural. But we didn't have a really good explanation," Meacham told Live Science.

Now the divers and archaeologists have at least one explanation. After connecting with a group of archaeologists — a partnership that blossomed as the cave divers took thousands of photos and collected samples for the scientists — the evidence was overwhelming that these sites were mines. In essence, prehistoric people were prospecting for and mining ochre in the caves, and they were making tools out of whatever appropriately-sized rocks they could find along the way, including broken-off stalactites from the ceiling and stalagmites from the floor, which the Indigenous people used to hammer, chip and smash away the flowstone (sheetlike mineral deposits) that covered the ochre.

Mining for ochre

The caves may be underwater now, but from about 21,500 until about 13,000 to 8,000 years ago, the Camilo Mina, Monkey Dust and Sagitario cave systems were dry and walkable. Even so, entering them would have been perilous. At La Mina ("the mine" in Spanish), Indigenous people would have walked down "naturally darkened passages, encountering overhead hazards and narrow restrictions well into the dark zone of Sagitario, up to at least 650 meters [2,132 feet] from natural light," the researchers wrote in the study. 

Related: Photos: Diving for ancient offerings in Lake Titicaca 

The divers retrieved samples of ochre, calcite rafts (lacelike crystals that form in still waters) and charcoal for the scientists to analyze and date. The ochre contained high-purity iron oxides, meaning it could make a vibrant, fine-grained red pigment, the researchers found. The team dated the mining activities using radioactive carbon in the  charcoal, examining the presence of the calcite rafts that formed after the mining events, and consulting the sea-level rise record. These methods indicated that Indigenous people had mined the western part of the cave system from about 11,400 to 10,700 years ago, just as the Pleistocene epoch was transitioning to the Holocene epoch.

"To me, that says that there's some degree of intergenerational knowledge being passed down. There is continuity of practice," MacDonald said. Mining happened in at least two other locations in the cave system, so it's even possible that mining was practiced on a regional space, she noted. 

Why mine at all?

While it's unclear how the Indigenous people used the ochre, previous studies have suggested that the mineral served as an antiseptic; a sunscreen; as something to eat; and as tick or lice repellent. It may also have been used for hide tanning, tool building and for purging parasites. 

The ochre from La Mina and Camilo Mino was high in arsenic, approaching 4,000 parts per million (ppm), "which is quite a bit, as far as ochre goes," MacDonald said. That ratio is much higher, for instance, than the 10 parts per billion of arsenic that the U.S. Food and Drug Administration allows in bottled water. However, arsenic, a neurotoxin, is known to repel pests, so perhaps that's a clue to how it was used, MacDonald said.

"For all we know, maybe they're just mining a whole bunch of bug repellent," she said.

Whatever the reason, the study shows that "early human groups in the Americas were already engaged in complex activities that went much beyond their own survival," Hubbe told Live Science in an email. "The mining of ochre from the caves suggest[s] that there was an important social meaning to this mineral and, even though we cannot really say what they were using this material for at this point, it does show it was immensely valuable and important for them."

The study was published online July 3 in the journal Science Advances. 

Originally published on Live Science.

A pair of 99-million-year-old cockroaches are rewriting the early history of the underworld.

The ancient roaches, found preserved in amber in Myanmar, are the oldest-known examples of "troglomorphic" organisms — creatures that adapted to the weird, dark environments of caves. And they're the only such dark-adapted creatures known from the Cretaceous period, having scurried around in the world's shaded crevices even as Tyrannosaurus rex walked the Earth. Nowadays, biologists have plenty of examples of cockroaches and of cave-dwelling insects with small eyes and wings, pale bodies, and long arms and antennae. But these specimens, from two distinct, related species, are the oldest animals ever found with those traits.

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"Caves lack unequivocal fossils before the Cenozoic," the researchers wrote in a paper describing their find, referring to a later period after the mass extinction (known as the K/Pg boundary) when dinosaurs died and mammals rose to their current prominence.

And even cave fossils from after the extinction tend to be of animals that spent only some of their time in caves, using them as shelters in between excursions into the sunlit world.

"Cave environments are well suited for fossilization of bones and coprolites [or fossilized feces] and the fossil record of cave mammals includes rodents, ungulates, marsupials, ursids, felids, hyaenids, canids, primates and humans," they wrote — all species with plenty of bones and poop. They added that "there is no relevant fossil record of any troglomorphic fauna before K/Pg with the exception of the present find."

Until now, the history of cave-dwelling cockroaches was known to go back to the Cenozoic era, which began about 65 million years ago. But researchers had long suspected that cave-dwelling roaches might date back to the dinosaur age, the researchers wrote, based on genetic analyses. But there had never before been firm evidence.

These two "exquisitely preserved" species, they said, according to a news article on Phys.org, were likely descendants of a common ancestor from earlier in the Cretaceous, before continental drift separated their homes on the supercontinent Gondwana.

It's not clear, the researchers noted, how the roaches ended up so well preserved. Amber fossils are common for small creatures that live near trees, because amber is fossilized tree resin. It's possible, the researchers suggested, that ancient resin dripped from tree roots into the cockroaches' caves and then hardened around the paleo-arthropods.

The study researchers, hailing from several institutions in Slovakia, China, Russia and Thailand, detailed their discovery online Feb. 11 in the journal Gondwana Research.

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Originally published on Live Science.

To light their way, these late Stone Age people likely burned bundles of pine (Pinus) sticks, which archaeologists also found in the cave, known as Grotta della Bàsura, in northern Italy.

The cave's ceiling was so low, that at one part, the ancient explorers were forced to crawl, leaving behind "the first evidence ever of human footprints left during crawling locomotion," that is, in a "crouching walk" position, said study first author Marco Romano, a postdoctoral researcher at the Evolutionary Studies Institute at the University of the Witwatersrand, South Africa. [In Photos: Stone Age Human Footprints Discovered]

Researchers have known about the ancient human presence in Grotta della Bàsura since the 1950s. But the new analysis is the first high-tech look at these particular trackways, in which the researchers used laser scans, sediment analysis, geochemistry, archaeobotany and 3D modeling to study the prints.

There were so many prints — 180 in all — that the researchers were able to piece together what happened that day during the upper Paleolithic (also known as the late Stone Age). According to the different sizes of footprints, it appears there were five people: a 3-year-old, 6-year-old, a pre-adolescent (8- to 11-year-old) and two adults, the researchers found.

This group was barefoot and didn't appear to be wearing any clothes (at least not that left any imprints in the cave). After walking nearly 500 feet (150 meters) into the cave, the party arrived at the "Corridoio delle Impronte" (footprint corridor), and then fell into single file, with the 3-year-old in the rear.

"[They] walked very close to the side wall of the cave, a safer approach also used by other animals (e.g., dogs and bears) when moving in a poorly lit and unknown environment," Romano told Live Science in an email.

Shortly thereafter, the cave roof dropped to below 31 inches (80 centimeters), forcing the adventurers to crawl, "placing their hands and knees on the clay substrate," Romano said.

The explorers then passed a bottleneck of stalagmites; traversed a small pond, leaving deep tracks on the waterlogged ground; climbed a small slope beyond the "Cimitero degli Orsi" (cemetery of the bears); and finally arrived at the terminal room "Sala dei Misteri" (room of mysteries), where they stopped.

Once in that room, "the adolescent and children started collecting clay from the floor and smeared it on a stalagmite at different levels according to height," Romano said. The group's torches left several charcoal traces on the walls. Then they left the cave.

The motley crew shows that "very young children were active members of the upper Palaeolithic populations, even in apparently dangerous and social activities," Romano said.

The new study is "a beautifully presented piece of work," said Matthew Bennett, a professor of environmental and geographical sciences at Bournemouth University in the United Kingdom, who was not involved in the research. "It's an example of the sophistication with which we can now record prints, whether they be humans or animals." [Photos: Dinosaur Tracks Reveal Australia's 'Jurassic Park']

However, given that researchers already knew that ancient humans lived in the area and used the cave, the finding doesn't add much to the scientific understanding of late Stone Age people, Bennett said. "It's a group of individuals exploring a cave, which is cool, but we knew that anyway," he told Live Science.

Bennett added that it's not uncommon to find the footprints of children intermingled with those of adults from this time. In part, that's because children likely outnumbered adults during the upper Paleolithic and because children take more steps than adults, as their legs are shorter. Moreover, "[children] do silly things — they dance around, they run around, they don't walk economically in one direction," Bennett said. "It makes statistical sense that we should be finding lots of children's footprints."

The study was published online today (May 14) in the journal eLife.

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Originally published on Live Science.

Six Neanderthals who lived in what is now France were eaten by their fellow Neanderthals some 100,000 years ago, according to gruesome evidence of the cannibalistic event discovered by scientists in a cave in the 1990s.

Now, researchers may have figured out why the Neanderthals, including two children, became victims of cannibalism: global warming.

While prior studies have interpreted Neanderthal remains to find proof of cannibalistic behavior, this is the first study to offer clues as to what may have led Neanderthals to become cannibals. Scientists found that rapid shifts in local ecosystems as the planet warmed may have extinguished the animal species that Neanderthals ate, forcing them to look elsewhere to fill their bellies. [25 Grisly Archaeological Discoveries]

The researchers examined a layer of sediment in a cave known as Baume Moula-Guercy, in southeastern France. There, excavations in 1999 by another team of scientists had uncovered 120 Neanderthal bones from six individuals that showed signs of being cannibalized.

Later, in 2014, another group of researchers analyzed the cave deposits to a depth of 26 feet (8 meters), dividing them into 19 layers associated with three climate shifts. For the new study, the authors turned their attention to layer 15, a silty sediment layer about 16 inches (40 centimeters) thick, covering approximately 98 to 131 feet (30 to 40 m) of the cave floor.

In that layer, charcoal and animal bones were so well-preserved that scientists could reconstruct an environmental snapshot representing 120,000 to 130,000 years ago. They discovered that the climate in the area was likely even warmer than it is today, and that the transition from a cold, arid climate to a warmer one happened quickly, "maybe within a few generations," study co-author Emmanuel Desclaux, a research associate at the University of Nice Sophia Antipolis in France, told Cosmos magazine.

As the animals that once populated the landscape vanished, some Neanderthals ate what they could find — their neighbors.

Cannibalism is by no means exclusive to Neanderthals, and has been practiced by humans and their relatives "from the early Palaeolithic to the Bronze Age and beyond," the study authors reported. The behavior adopted by the starving Neanderthals in the Baume Moula-Guercy should therefore not be viewed as "a mark of bestiality or sub-humanity," but as an emergency adaptation to a period of severe environmental stress, according to the study.

The findings were published online in the April issue of the Journal of Archaeological Science.

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Originally published on Live Science.

An international team of astronauts has discovered a new species of blind, colorless, cave-dwelling crustacean — and they didn't even have to leave Earth to find it.

The fingernail-size crustacean, named Alpioniscus sideralis after the Latin word for "stellar," was discovered scuttling about a pitch-black pool in the Sa Grutta cave system below Sardinia, Italy. Fledgling astronauts discovered the tiny cave-dweller while spending six nights belowground as part of the European Space Agency's CAVES training program, which encourages International Space Station candidates to conduct research together in perilous subterranean environments.

During a 2012 expedition underground, astronaut trainees from Europe, the United States, Russia, Canada, Japan and China encountered the tiny, translucent crustaceans in a small cave pond. The astronauts lured the creatures out of the water using a bait of liver and rotten cheese, then transported the specimens back to the surface. [In Images: Creepy, Crawly Cave Creatures]

Molecular analysis showed that A. sideralis' genetics didn't match that of any other species collected from the region, allowing the intrepid astronauts to describe it for the first time in a new study published December 2018 in the journal ZooKeys.

A. sideralis was revealed to be a type of woodlice — tiny crustaceans that left the water to colonize land millions of years ago. Remarkably, A. sideralis seems to have done an evolutionary about-face, turning its armored back on the land and returning to subterranean waters like the cave pools of Sardinia.

"I would like to think that when humans land on Mars and explore its caves, this experience will help them to look for other species, knowing that life has few limits and can develop in the most inhospitable places," Paolo Marcia, a zoologist from the University of Sassari and co-author of the study, said in a statement.

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Originally published on Live Science.

An Israeli-led research team believes that Malham Cave in the Negev Desert is the longest salt cave in the world, measuring more than 6 miles (10 kilometers) in total length.

"Salt cave" is a literal term here: Malham sits under Mount Sedom, just southwest of the salty Dead Sea, and its walls are made out of the same sort of salt on your kitchen table. Radiocarbon dating suggests it's about 7,000 years old, its many passages carved by the very occasional rain storms that pass through the region. Even now, Malham continues to grow when water flows in and dissolves more of the salt, according to a statement.

A team of 80 cavers from nine countries explored the cave's many crevasses using laser measurement tools. The full map and results of their explorations haven't yet been published. But, in the statement, the team compared the total length (the result of adding up the lengths of all the different splintering passages) with the now former record-holder. [Image Gallery: Rainbow of Life in Great Salt Lake]

"By comparison, Iran's Qeshm Island salt cave, now the world's second largest salt cave, measures only 6,580 meters [or 4.1 miles]," they said.

Achieving that measurement was hard work.

"We cavers worked 10-hour days underground, crawling through icy salt channels, narrowly avoiding salt stalactites and draw-dropping salt crystals," Efraim Cohen, a caver with Hebrew University's Cave Research Center, said in the statement. [Image Gallery: Rainbow of Life in Great Salt Lake]

Cavers are still exploring some of the hardest-to-reach places of the cave system, he said, suggesting a bit more distance might be added to the total length.

Mount Sedom sits near the Dead Sea, a shrinking salt lake (and lowest point on Earth) that extends into Jordan, Israel and the occupied West Bank. The mountain sits outside the West Bank, and according to the statement was discovered in the 1980s.

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Originally published on Live Science.

The Neanderthals and Denisovans — both relatives of modern humans — were roommates, literally, for thousands of years in a remote Siberian cave, two new studies find.

Back in ancient times, this cave would have been a real estate agent's paradise; it's the only place in the world that Neanderthals, Denisovans and possibly even modern humans lived in together throughout history, the researchers found.

The cave was so popular that hominins (a group that includes humans, our ancestors and our close evolutionary cousins like chimps) lived there almost continuously over both warm and cold periods during the past 300,000 years, the researchers found. [In Photos: Bones from a Denisovan-Neanderthal Hybrid]

By analyzing fossils and DNA, the researchers learned that the enigmatic Denisovans lived in the cave from at least 200,000 to 50,000 years ago, and the Neanderthals lived there between 190,000 and 100,000 years ago.

It's not completely out of the blue that Neanderthals and Denisovans mingled. In 2018, researchers published a study in the journal Nature on the bone fragment of a teenage girl who had a Neanderthal mother and a Denisovan father, the first direct evidence that the two hominin groups interbred.

The new research shows that this girl, whose remains were found in Denisova Cave, lived about 100,000 years ago, the scientists said.

Dating bonanza

Researchers have been excavating Denisova Cave, located in the foothills of the Altai Mountains in Siberia, for the past 40 years.

In 2010, the cave gained worldwide recognition when scientists announced they had found the finger bone of a previously unknown hominin, and published its genome. They named the hominin the Denisovans (deh-NEESE-so-vans), after the cave.

However, until now, researchers had few artifacts to date, so they weren't sure exactly when the cave's inhabitants lived there. Now, two new studies reveal a chronology for the cave's inhabitants.

In one study, researchers in Australia and Russia used optical dating to determine the age of the cave's sediments. They couldn't use radiocarbon dating because that can reliably date organic objects to only 50,000 years ago. In contrast, optical dating allows scientists to find out when quartz and feldspar grains in the soil were last exposed to sunlight.

In the other study, researchers in Germany, the United Kingdom, Australia, Russia and Canada looked at the predictable decay of a radioactive carbon isotope (radiocarbon dating) to figure out the ages of bone, tooth and charcoal fragments found in the upper layers of the site; and then they created a statistical model that integrated all of the cave's newly discovered dates.

"We had to invent some new methods to date the deepest and oldest deposits and construct a robust chronology for the sediments in Denisova Cave," study co-researcher Bo Li, an associate professor at the School of Earth, Atmospheric and Life Sciences at the University of Wollongong in Australia, said in a statement.

Moreover, the new statistical model helped "incorporate all of the dating evidence available for these small and isolated fossils, which could easily have been displaced after deposition," study lead researcher Katerina Douka, an archaeological scientist at the Max Planck Institute for the Science of Human History in Germany, said in the statement. [Denisovan Gallery: Tracing the Genetics of Human Ancestors]

Even so, questions remain about the dated material in the cave. For instance, "do the human fossils derive from human occupations or from, say, carnivore activity, and have they been transported far from their original depositional location?" asked study researcher Chris Stringer, a research leader of human origins at London's Natural History Museum.

Human history

A conundrum about the cave persists: Did modern humans live there? Our species (Homo sapiens) was present in other parts of Asia by 50,000 years ago, but it's unclear whether any H. sapiens interacted with the Denisovans in the cave. That's because scientists have yet to find any fossil or genetic traces of modern humans in the cave, although researchers have found a hominin bone dating to between 50,000 and 46,000 years ago. The team couldn't procure any DNA from it, so it's unclear what species the bone belonged to.

In addition, it's possible that modern humans made some of the artifacts in the cave.

"Another open question is whether Denisovans or modern humans made the oldest bone points and personal ornaments [tooth pendants] found in the cave," Tom Higham, a professor of archaeology at the University of Oxford who worked on the radiocarbon study, said in the statement. "With direct dates of between 43,000 and 49,000 years ago, they are the earliest such artifacts known from all of northern Eurasia."

But Stringer said he would put his money on early modern humans.

"Early modern humans can be mapped elsewhere at this date, for example at Ust'-Ishim in Siberia," Stringer told Live Science in an email. "But the authors of the [radiocarbon dating] paper rather surprisingly argue that it's most parsimonious to assume that Denisovans were responsible, even though no Denisovans are yet known as late as that in the sequence.

"Only more discoveries and more research can resolve that question satisfactorily," Stringer added.

The two studies were published online yesterday (Jan. 30) in the journal Nature.

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Originally published on Live Science.

A helicopter team counting caribou in British Columbia, Canada, recently made an unexpected discovery during an aerial survey: Crewmembers spied an opening to a massive cave that had never been seen before and which might be the largest cave in the country.

Found in April in an alpine valley in Wells Gray Provincial Park, the cave's mouth gapes 328 feet (100 meters) across — if the Statue of Liberty were tipped over on its side, it would just about span the opening. The width of the cave is similarly impressive, measuring 197 feet (60 m), and the cave extends at least 443 feet (135 m) straight down, the Canadian Broadcasting Corporation (CBC) reported.

A biologist with the helicopter crew that spotted the sizable opening dubbed it "Sarlacc's Pit," after the lair that housed the predatory sarlacc in the "Star Wars" movie "Return of the Jedi," according to the CBC. The deep and wide cave was probably hollowed out by glaciers over tens of thousands of years, and it gradually became exposed to the sky after the glaciers receded. [Photos: Amazing Caves Around the World]

While researchers have yet to thoroughly explore the site, a preliminary investigation in September hinted that the cave was "of national significance," Canadian Geographic reported.

"The scale of this thing is just huge and about as big as they come in Canada," archaeological surveyor John Pollack, one of the researchers who explored the cave, told Canadian Geographic.

During that expedition, a breathtaking view of the vast cave was captured in aerial footage by geologist Catherine Hickson, an adjunct professor at the University of British Columbia in the Department of Earth, Ocean and Atmospheric Sciences, according to the National Post.

The video was shared to YouTube on Nov. 30 by Canadian Geographic. Seen from the air, the cave resembles a giant bite taken out of the hillside. Steep, rocky walls plunge downward, and a waterfall cascades more than 525 feet (60 m) over the edge.

After rushing water tumbles over the precipice into the cave's depths, it likely flows into a subterranean river that emerges above ground 6,890 feet (2,100 m) away, at an elevation that's about 1,640 feet (500 m) lower than the water's entry point, Pollack told Canadian Geographic. This hints at the length of the underground chambers in the cave, he explained.

While the unofficial name "Sarlacc Pit" certainly holds appeal for "Star Wars" fans, British Columbia province representatives will be working closely with First Nations people in the region to find out if there is an existing indigenous name for the cave, Canadian Geographic reported. Further investigation of the cave will take place in 2020, Hickson told CBC.

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Original article on Live Science.

For urban graffiti artists, their work is sometimes on display all too briefly before rival artists cover it up. And ice age cave art suffered a similar fate, experts have discovered.

Archaeologists suspected that two caves called Grottes d'Agneux and located in eastern France might harbor artwork produced thousands of years ago by human artists. The researchers had strong suspicions that the art was there, but the cave walls were so covered with layers of more-recent graffiti (from the 16th to 19th centuries) that the ancient art had likely been hidden for hundreds of years, representatives of the University of Tübingen in Germany reported yesterday (Nov. 14) in a statement.

Scientists with the university and researchers from Spain recently used scanning technology to peer through the graffiti layers, reconstructing carved prehistoric images of a horse and a deer buried underneath. [In Photos: The World's Oldest Cave Art]

The graffiti covering the cave walls was mostly inscriptions of names and dates with a few figurative pictures, research team leader Harald Floss, a Tübingen University professor of early prehistory and quaternary ecology, told Live Science in an email. Because the caves are in a picturesque part of the countryside with spectacular views, many people have visited the location over time — and plenty of them left their mark in the cave, Floss said.

For 150 years, archaeologists have explored France's southern Burgundy region and found abundant remnants of Paleolithic culture — the earliest period of human cultural development. Because there are so many Paleolithic sites in this part of France, archaeologists have long thought that there must be cave art in the Saône-et-Loire district, according to Floss.

Painted or engraved caves are found "in nearly every dense palaeolithic region of Europe," Floss said. However, the deer and horse paintings are the district's first examples of cave art created by Paleolithic humans, university representatives said in the statement.

After scans revealed the figures, the scientists reconstructed the artwork with image-processing software. Then, the researchers used carbon-14 dating of charcoal in the cave and in the art to reveal the age of the paintings. Carbon-14, a carbon isotope, breaks down over time. By examining how much of the isotope in an object has decayed, scientists can calculate how old the object is; in this case, the art was found to be 12,000 years old.

The region in France where archaeologists discovered the cave art is significant, because it represents a zone where modern humans may have encountered Neanderthals. Evidence uncovered there could offer intriguing clues about human-Neanderthal interactions, Floss said.

Following the scientists' analysis of the carvings, French authorities inspected the caves and confirmed their archaeological significance for signs of early humans, according to the statement. The researchers said they're planning further investigations of the site.

The findings were published in August in the book "Palaeolithic Rock and Cave Art in Central Europe?" (Verlag Marie Leidorf, 2018).

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Originally published on Live Science.