Sometime in the late 1600s, in the lush forests of Mauritius, the very last dodo took its last breath. After centuries of untroubled ferreting in the tropical undergrowth, this species met its untimely end at the hands of humans, who had arrived on the island less than 100 years before. With their penchant for hunting, habitat destruction and the release of invasive species, humans undid millions of years of evolution, and swiftly removed this bird from the face of the Earth.
Since then, the dodo has nestled itself in our conscience as the first prominent example of human-driven extinction. We've also used the dodo to assuage our own guilt: the creature was fat, lazy and unintelligent — and as popular story goes, those traits sealed its inevitable fate.
But in fact, we couldn't be more wrong, said Julian Hume, a paleontologist and research associate with the National History Museum in the United Kingdom. He studies the fossils of extinct species, and has devoted a portion of his career to correcting the dodo's dismal reputation. By digitally modelling the remains of a dodo’s skeleton, he's produced a 3D digital reconstruction that draws an altogether different picture of a bird that was faster, more athletic and far brainier than popular culture has led us to believe. "It was nothing like this big, fat, bulgy thing that was just waddling around. This bird was super adapted to the environment of Mauritius," Hume told Live Science. Instead, humans' unrelenting exploitation was the real culprit behind the dodo's untimely death.
But that's not all we've gotten wrong. Despite the commonly held belief, the dodo actually wasn't the first creature that humans drove to extinction — not by a long shot. In fact, humanity was wiping out the world's fauna thousands of years before we set eyes on the dodo. "There was certainly a lot more going on before and after that event," said Hume.
So, if the iconic dodo wasn't the first species we drove to the brink, then which animal gets this disheartening title, instead?
Humans on the move
We've grown accustomed to thinking about human-driven species extinction as a relatively recent trend in our history. Yet, researchers have found convincing palaeontological evidence that dismantles that idea.
"The real problem started when we, as humans, started migrating," Hume said. That starting point is still debated, but most recent estimates suggest that migrations that led to lasting populations of humans spread across the globe began with the movement of hominids — Neanderthals and other ancient human relatives, as well Homo sapiens — out of Africa and southeast Asia, roughly 125,000 years ago. This is where the evidence gets interesting. As humans left their ancestral homes, and over the following tens of thousands of years went on to colonize Eurasia, Oceania, North and South America, the fossil record shows a parallel uptick in the extinction in large-bodied animals — also known as megafauna — across those continents.
"As [hominids] migrated out of Africa, you see this incredibly regular pattern of extinction," said Felisa Smith, a professor of ecology and evolutionary biology at the University of New Mexico, who studies how animals' body sizes have changed over the course of history. As she and her colleagues explained in a 2018 study published in the journal Science, each time our ancestors set foot in new places, fossil records show that large-bodied species — the humongous prehistoric relatives of elephants, bears, antelope and other creatures — started going extinct within a few hundred to 1,000 years, at most. Such rapid extinction timescales don't occur at any other point in the last several million years (not since the non-avian dinosaurs were wiped out by an asteroid about 65 million years ago.) "The only time you see it is when humans are involved, which is really striking," Smith said.
Some of those early lost species would seem like fantastical beasts if they roamed Earth today. For example, "There was an armadillo-like thing called the glyptodon, which was the size of a Volkswagen bus," Smith told Live Science. Glyptodons, many equipped with vicious-looking spiked tails, disappeared from the Americas at the end of the last ice age, roughly 12,000 years ago — which is probably connected to the earlier arrival of humans there. The number of gigantic Eurasian cave bears, several hundred pounds heavier than grizzly bears today, went into a steep decline about 40,000 years ago, around the same time that humans began to spread across their habitat. South America was once home to lumbering giant ground sloths — and humans were also the most likely candidate in their demise, about 11,000 years ago.
Related: How often do ice ages happen?
What made large animals, in particular, so susceptible to humanity's spread? Megafauna likely represented food, or a threat, to incoming humans. What's more, animals that had never encountered humans before were probably unwary of these strange newcomers migrating into their unspoiled lands, which might have increased their vulnerability to attack. Unlike other smaller animals that breed more rapidly, megafauna also reproduce more slowly and so have smaller populations compared with other species, Hume explained: "So if you take out a big section of [a population] they cannot reproduce quickly enough to build up numbers again."
It wasn't just hunting that posed a threat — but also the spread of human-caused fires that would have destroyed swathes of habitat, and increasing competition from humans for food. For instance, it's thought that by preying heavily on the same herbivores, growing numbers of hungry humans helped drive the extinction of the short-faced bear, a gigantic South American species that once stood at over 10 feet (3 meters) tall, and died out roughly 11,000 years ago. Climate change, paired with human impacts like hunting, also proved to be a lethal combination for some megafauna — most famously, mammoths, which went extinct about 10,500 years ago (except for the dwarf woolly mammoth, which survived until about 4,000 years ago on an island off northern Russia). "If you combine climate change with a negative human impact, it's a disaster," said Hume.
All of this is to say that humans have systematically wiped out the species around us from almost the beginning of our history. Our migration prompted "a disaster across the world," said Hume. "We weren't very pleasant." Unfortunately, we've continued our ancestors' legacy, with, among thousands of other species, the eradication of Madagascan hippos 1,000 years ago, the loss of moa birds in New Zealand 600 years ago, and the decimation of passenger pigeons 106 years ago. We are also responsible for ongoing extinctions today.
But this still hasn't answered the question of what species went extinct first. And here's the catch: the data on human-driven extinction across the planet is only reliable as far back as about 125,000 years— but that doesn't mean we weren't driving animals to extinction before that in Africa, too. In fact, there's compelling evidence to suggest that before humans migrated out, they unleashed their hunting instincts on species there as well.
Smith's research has revealed that the average body size of African animals 125,000 years ago was only half that of species that were present on other continents around the world. "Africa is one of the largest continents, so it should have had a mean body size similar to that of the Americas and Eurasia where it was roughly about 100 kilograms [220 lbs.]," Smith said. "The fact that it didn't suggests that there had already been an effect of hominids on megafauna in Africa, prior to 125,000 years ago."
In essence, because the rest of history tells us that humans are good at dispatching the largest creatures in an ecosystem, we can make a fairly safe assumption that hominids in Africa at the time could have been responsible for extinctions going even further back in time.
Still, there's no way to know for sure what that 'first' species would have been — though Smith takes a wild guess: "It was probably some species in the elephant family. But whether that's palaeomastodon, or stegodon" — the latter being a behemoth with tusks that measured 10 feet (3 meters) long - "I couldn't tell you."
Clues for the future
We may not have a clear answer to that original question - but perhaps the more important one to ask is what humanity's legacy of extinction can teach us about conservation, going into the future.
Past extinctions have revealed that when animals — especially megafauna — disappear, there are profound ecological consequences. Whole landscapes are transformed in the absence of their shaping effects, with changes to vegetation and species diversity. Smith has even published research showing that the decline of global megafauna in past millennia led to dips in the amount of methane they burped out — with potentially transformative consequences for global climate. What's more, when animals disappear, whole rafts of dependent species go down with them. The iconic dodo presents one such cautionary tale: when the birds died out, so did a Mauritian dung beetle that relied on dodo feces to survive.
Understanding human-driven extinctions of the past can help us figure out what the environmental consequences have been, explained Smith, and how we can limit those in the future by protecting the species that remain. Even the dodo's extinction provides clues that are helping us preserve ecosystems today. Hume is working on a project to catalog pollen spores present in the sediments around dodo fossils, to build up a detailed picture of the lush, palm-fringed forests they once roamed. That's helping conservationists to rewild the island with vegetation that was once there. "We're actually reconstructing the exact species of plants and trees from the environment the dodo was living in, before humans arrived," Hume said.
A bit of paradise was lost when we drove the dodo to extinction — not to mention the thousands of species whose demise came before that. But perhaps with hindsight, and the willingness to learn from our mistakes, some of that can be reclaimed.
Originally published on Live Science.
Live Science newsletter
Stay up to date on the latest science news by signing up for our Essentials newsletter.
Emma Bryce is a London-based freelance journalist who writes primarily about the environment, conservation and climate change. She has written for The Guardian, Wired Magazine, TED Ed, Anthropocene, China Dialogue, and Yale e360 among others, and has masters degree in science, health, and environmental reporting from New York University. Emma has been awarded reporting grants from the European Journalism Centre, and in 2016 received an International Reporting Project fellowship to attend the COP22 climate conference in Morocco.
This article ignores lots of scientific facts. The correlation of human migration and the extinction of many large species of Fauna is almost assuredly due to a catastrophic earth event...comet, asteroid, solar radiation event. There were simply not enough humans on the planet 12,000 years ago to kill off the millions of mammals that died. Northern Siberia alone was home to the mass graves of tens to hundreds of thousands of wooly mammoths who died with undigested food actually in their mouths. Blaming humans for this is illogical.Reply
"Smith's research has revealed that the average body size of African animals 125,000 years ago was only half that of species that were present on other continents around the world."Reply
At the same time it has IIRC the largest megafauna diversity of any continent. So it isn't as simple as one factor explaining everything (as usual).
Spike0311 said:This article ignores lots of scientific facts. The correlation of human migration and the extinction of many large species of Fauna is almost assuredly due to a catastrophic earth event...comet, asteroid, solar radiation event.
"Almost assuredly"? Such an event has no evidence and little rationale - apart from the large mass extinctions evolution is gradual - so the asserion goes in the other direction.
And notably the article do refer to science, it is rather that the area (of megafauna extinction) has a few competing hypotheses and it covers one. It is unlikely that one hypothesis will explain everything, c.f. how fossil genome sequencing showed that the wholly rhino had plenty of diversity right before its extinction - no sign of human predation putting pressure on them. But its habitat disappeared when the last glaciation did.
Spike Hyzer said:I would add that this theory is the best I've seen and undoubtedly accurate and also suggests that the human impact is responsible for ALL extinctions going back to the newly updated beginning of tool use at 3.2 million years.
Not quite that far back - and I also note that the North American megafauna extinction was unique - but it seems from Wikipedia that I may be wrong and the science has started to come down on one primary forcing for recent megafauna extinction. FWIW:
The Holocene extinction (see also Quaternary extinction event), occurred at the end of the last ice age glacial period (a.k.a. the Würm glaciation) when many giant ice age mammals, such as woolly mammoths, went extinct in the Americas and northern Eurasia. An analysis of the extinction event in North America found it to be unique among Cenozoic extinction pulses in its selectivity for large animals.(Fig. 10) Various theories have attributed the wave of extinctions to human hunting, climate change, disease, a putative extraterrestrial impact, or other causes. However, this extinction near the end of the Pleistocene was just one of a series of megafaunal extinction pulses that have occurred during the last 50,000 years over much of the Earth's surface, with Africa and southern Asia (where the local megafauna had a chance to evolve alongside modern humans) being comparatively less affected. The latter areas did suffer a gradual attrition of megafauna, particularly of the slower-moving species (a class of vulnerable megafauna epitomized by giant tortoises), over the last several million years.
Outside the mainland of Afro-Eurasia, these megafaunal extinctions followed a highly distinctive landmass-by-landmass pattern that closely parallels the spread of humans into previously uninhabited regions of the world, and which shows no overall correlation with climatic history ...
It cannot be ruled out that the first species "humans" wiped out was another hominid that was "in the way".Reply
After all, we are very good at killing things off!
If interactions between "modern" humans is any clue, killing off hominids that look very much like you, but are not like you, may have been an instinctive behavior.
This instinct might even persist to this day, at least in some of our human subspecies...........
Spike0311 said:There were simply not enough humans on the planet 12,000 years ago to kill off the millions of mammals that died.
After ruminating on these posts and the topic, I am compelled to reverse course and agree with @Spike0311 to some extent and consider the possibility that some of the most significant extinction events, at least in the northern hemisphere during the retreat of the glaciers was not primarily driven by human activities. For instance, fires have been cited as a man-made force of extinctions, but surely many of these were formed by lightning strikes if the conditions for massive fires were even right. Most are compelled to believe the native inhabitants would have valued the forests for its bounty of food, and avoided burning them down.
And many of the mega-fauna that went extinct at the beginning the glacial retreat were those in northern climates, and actually relied on the cool environment. Such a region likely minimized tree growth and provided large areas for grazing. And they would be relatively close to the the massive faces of these retreating ice sheets, and the consequences of their melting.
A notion has been proposed that many large mammals could have been killed off by ancient hunters in "Buffalo jumps" (1) . These were forced stampedes of animals over cliffs to their deaths, and ease of harvesting. But for bones beds with retained food in their mouths, this seems highly unlikely for the cause of death, and clearly unsupported by basic physiology. Instinctive behavior would have forced such stampeded animals to spit out any food in order to maximize breathing efficiency. In almost all cases, animal remains found with food in their mouths must have been killed by a rapid, catastrophic event. Any animal running from a threat is not going to have food in its mouth for very long.
To be sure, native North American hunters had been killing buffalo for thousands of years in such "over the cliff" drives. Evidence indicates such "hunts" started ca. 12,000 years ago, and was used up until at least 1500 bp. On the other hand, Europeans with long rifles almost drove the buffalo (aka bison) into extinction, killing millions for their hides, etc. The native American were given thousands of years to wipe out the buffalo, but there were ca. 30 million when the Europeans arrived. By the late 1880s, tens of millions were gunned down to ca. 100 specimens. What the cliffs and natives could not do for thousands of years took the Europeans just a few decades to wipe out millions of them. This puts a perspective on the ability of the native Americans to kill mega-fauna in large numbers. It clearly did not play out with buffalo. Why should it with other species much earlier? Doubtless the human population of glacial regions was at least several orders of magnitude less than at the appearance of the Europeans.
At any rate, mass killings of other species, so as to wipe out the large mega-fauna of thousands of years ago, is not documented in any of my searches. The searches do suggest however that the "breaking" of glacial dams occurred many times during the vast glacial retreats around the world, and the remains of numerous animals have been found, with food in their mouths, and all their bones crushed, but show no signs of butchering.
The release of nearby "glacial-melt lakes" onto grazing lands created massive tsunamis, carrying large boulders and crushing everything in its path for many miles from their source. Such events are known as "glacial lake outburst floods" (2), and could have killed various grazing animals (or carnivores) in large numbers over extended periods, and dramatically impacted their populations all around the line of glacial retreat. Keep in mind the reproduction rate of the mega-fauna was rather slow, as it is in most large mammals,
The most famous of glacial lake outburst floods is the largest - the Missoula Floods (3) and occurred between 15,000-12.000 bp. These floods alone appear to have wiped out virtually all life forms over vast expanses of terrain. The largest flood is believed to have released 500 cubic miles of water (the volume of Lake Erie!), and flooded vast areas of Washington and Oregon. It is estimated that at one time, "Portland" was under 200 feet of water from this flood. Similar massive flooding has also been found in Siberia. It is a certainty that large numbers of animals were wiped out, by the tens of thousands, if not more. And yes, many would have had food in their mouths because of their sudden demise by flash floods loaded with large boulders and rocks.
If one considers that such floods would have been rather common throughout the retreat of the main glacial ice sheets, and not just in the northwest, the impact of these floods to animals as well as terrain was likely substantial. The largest flood noted above was only the biggest and easiest to determine. However, since they are still a threat today with the comparatively trace number of glaciers remaining, over time, the retreat of these massive ices sheets very likely was a major threat to large mega-fauna which evolved in the cold and were largely reliant on the glaciers, any one of which could have also caused their deaths, in mass numbers. With food in their mouths!
The floods alone may not have wiped out all these "arctic" species, but they must have taken a substantial toll. A great deal of water was melting off glaciers, thousands of feet thick, and many lakes would have formed with varying magnitudes of flooding when their ice damns failed. Indeed, likely thousands of lakes collapsed, as the ice sheets were enormously deep and extensive. The contribution for glacial lake outburst floods to mass extinctions cannot be ruled out, and theoretically could be quite significant. The contributions of humans to their extinction, if any, is most likely by driving their continuously limited numbers to zero.
Below is an addendum to the brief overview posted above about the significant role glacial melting could have played in the slow demise of mega-fauna over extended periods of time.Reply
One aspect of large glacial lake floods which was neglected in the post above was the lasting impact on the flooded terrain, mostly south of the melting glaciers. In many areas. these floods would have hammered large areas of fertile grazing lands, sweeping away everything right down to the bed rock over enormous areas. This was a recurring theme in a number of treatments I read on the results of large glacial lake floods - the lasting damage to the ecosystem after the floods wiped out large areas of once prime habitat for many animals.
Such changes in topography would have been extensive, and effectively permanent with regard to most large animals living in the area, especially the large herbivores. They may very well not only have been killed in large numbers by such floods, but also had their grazing lands destroyed by them as well.
Survivors may have had it difficult to recover to previous levels since the terrain would not revert to grass lands for hundreds or thousands of years. The cumulative impact of the terrestrial changes that these animals were exposed to by the continuous, massive glacial lake flooding should be factored into their ability to survive the results of the retreating glaciers, much less any predators who might wish to dine on them.