Results show that the correlation between climate change … and the loss of megafauna is weak
A new study unequivocally points to humans as the cause of the mass extinction of large animals all over the world during the course of the last 100,000 years.
Was it mankind or climate change that caused the extinction of a considerable number of large mammals about the time of the last Ice Age? Researchers at Aarhus University have carried out the first global analysis of the extinction of the large animals, and the conclusion is clear – humans are to blame.
“Our results strongly underline the fact that human expansion throughout the world has meant an enormous loss of large animals,” says Postdoctoral Fellow Søren Faurby, Aarhus University.
Was it due to climate change?
For almost 50 years, scientists have been discussing what led to the mass extinction of large animals (also known as megafauna) during and immediately after the last Ice Age.
One of two leading theories states that the large animals became extinct as a result of climate change. There were significant climate changes, especially towards the end of the last Ice Age – just as there had been during previous Ice Ages – and this meant that many species no longer had the potential to find suitable habitats and they died out as a result. However, because the last Ice Age was just one in a long series of Ice Ages, it is puzzling that a corresponding extinction of large animals did not take place during the earlier ones.
Theory of overkill
The other theory concerning the extinction of the animals is ‘overkill’. Modern man spread from Africa to all parts of the world during the course of a little more than the last 100,000 years. In simple terms, the overkill hypothesis states that modern man exterminated many of the large animal species on arrival in the new continents. This was either because their populations could not withstand human hunting, or for indirect reasons such as the loss of their prey, which were also hunted by humans.
First global mapping
In their study, the researchers produced the first global analysis and relatively fine-grained mapping of all the large mammals (with a body weight of at least 10 kg) that existed during the period 132,000–1,000 years ago – the period during which the extinction in question took place. They were thus able to study the geographical variation in the percentage of large species that became extinct on a much finer scale than previously achieved.
The researchers found that a total of 177 species of large mammals disappeared during this period – a massive loss. Africa ‘only’ lost 18 species and Europe 19, while Asia lost 38 species, Australia and the surrounding area 26, North America 43 and South America a total of 62 species of large mammals.
The extinction of the large animals took place in virtually all climate zones and affected cold-adapted species such as woolly mammoths, temperate species such as forest elephants and giant deer, and tropical species such as giant cape buffalo and some giant sloths. It was observed on virtually every continent, although a particularly large number of animals became extinct in North and South America, where species including sabre-toothed cats, mastodons, giant sloths and giant armadillos disappeared, and in Australia, which lost animals such as giant kangaroos, giant wombats and marsupial lions. There were also fairly large losses in Europe and Asia, including a number of elephants, rhinoceroses and giant deer.
Weak climate effect
The results show that the correlation between climate change – i.e. the variation in temperature and precipitation between glacials and interglacials – and the loss of megafauna is weak, and can only be seen in one sub-region, namely Eurasia (Europe and Asia). “The significant loss of megafauna all over the world can therefore not be explained by climate change, even though it has definitely played a role as a driving force in changing the distribution of some species of animals. Reindeer and polar foxes were found in Central Europe during the Ice Age, for example, but they withdrew northwards as the climate became warmer,” says Postdoctoral Fellow Christopher Sandom, Aarhus University.
Extinction linked to humans
On the other hand, the results show a very strong correlation between the extinction and the history of human expansion. “We consistently find very large rates of extinction in areas where there had been no contact between wildlife and primitive human races, and which were suddenly confronted by fully developed modern humans (Homo sapiens). In general, at least 30% of the large species of animals disappeared from all such areas,” says Professor Jens-Christian Svenning, Aarhus University.
The researchers’ geographical analysis thereby points very strongly at humans as the cause of the loss of most of the large animals.
The results also draw a straight line from the prehistoric extinction of large animals via the historical regional or global extermination due to hunting (American bison, European bison, quagga, Eurasian wild horse or tarpan, and many others) to the current critical situation for a considerable number of large animals as a result of poaching and hunting (e.g. the rhino poaching epidemic).
The results have just been published in the article Global late Quaternary megafauna extinctions linked to humans, not climate change in Proceedings of the Royal Society B.
My mistake, clumsy fingers and eyes missed a / in a closing blockquote I think.
Steve P says:
June 5, 2014 at 5:11 pm
There are a more than three kill sites. I provided links to or mention of five. Given the odds against preservation, it’s surprising there’s even one.
The American Lion is not technically a Cave Lion. Panthera spelaea, the European or Eurasian Cave Lion, is distinct from the American Lion Panthera atrox (sometimes wrongly called a Cave Lion). Both differ significantly from Panthera leo, the modern lion. There are however some taxonomic lumpers who consider them all subspecies of the same species.
This genetic study however pretty much clinches the three taxa scenario, to which I’ve always subscribed. One distinct feature of American lions is that their brain cases suggest greater intelligence than other species. They might have been smart enough to hunt from downwind, which modern lions don’t:
http://www.uni-mainz.de/FB/Biologie/Anthropologie/MolA/Download/Barnett%20et%20al.%202009.pdf
Abstract
Lions were the most widespread carnivores in the late Pleistocene, ranging from southern
Africa to the southern USA, but little is known about the evolutionary relationships among
these Pleistocene populations or the dynamics that led to their extinction. Using ancient DNA
techniques, we obtained mitochondrial sequences from 52 individuals sampled across the
present and former range of lions. Phylogenetic analysis revealed three distinct clusters: (i)
modern lions, Panthera leo; (ii) extinct Pleistocene cave lions, which formed a homogeneous
population extending from Europe across Beringia (Siberia, Alaska and western Canada); and
(iii) extinct American lions, which formed a separate population south of the Pleistocene ice
sheets. The American lion appears to have become genetically isolated around 340 000 years
ago, despite the apparent lack of significant barriers to gene flow with Beringian populations
through much of the late Pleistocene. We found potential evidence of a severe population
bottleneck in the cave lion during the previous interstadial, sometime after 48 000 years,
adding to evidence from bison, mammoths, horses and brown bears that megafaunal populations
underwent major genetic alterations throughout the last interstadial, potentially
presaging the processes involved in the subsequent end-Pleistocene mass extinctions.
ATheoK says:
June 5, 2014 at 5:25 pm
Coyotes have never been persecuted the way that wolves were. They have actually benefited from European settlement in North America.
The first public act in Oregon before it was even a territory was a wolf bounty. Few wolves survived in the West. They’re now being reintroduced from Alaska & Canada. In the SW some would move in from Mexico.
The pattern of extinctions strongly suggests human predation. We started on the biggest & worked our way down. Mammoths went long before the mastodons, for instance. Horses, ground sloths, camelids & the extinct bison species lasted longer. Yes, same thing happened in South America.
Here’s a Chilean mastodon site with which I’m familiar:
http://en.wikipedia.org/wiki/Monte_Verde
Virtually all of the logic claimed to support man killing off only selected animals commonly called mega fauna.
It is not a coincidence because man was not living in large areas of North America when the critters went missing. Other places where it is a coincidence shows another example of coincidence is not causation!
Mega critters surviving prior inter-glacials is not proof for anything! That’s a classic ‘we don’t know so it is man’s fault’ argument.
“…Our projectile weapons were far more effective & safer against big game than Neanderthal thrusting spears…”
??? As I mentioned above; try and prove that with modern arrow technology and any of the dangerous critters still around. Yes, experienced hunters have successfully taken game… Let’s see you do it and return to tell us that primitive technology erased entire lines of critters. Modern hunters with rifles still suffer casualties at a rate higher than small groups of hunters/gatherers.
Locations where there are large piles of bones… How large? Tens of thousands? Accumulated over millennia or just a few falls. Mankind is extremely good at opportunism.
Now show us where primitive hunter/gatherers decimated an entire herd or flock…
Steve P says:
June 5, 2014 at 5:11 pm
http://www.amnh.org/science/biodiversity/extinction/Day1/overkill/Bit2.html
AMNH cites 15 sites that have produced evidence for mammoth hunting in North America. Overkill advocate Martin claims the site scarcity should be seen not as evidence of rare hunting, but rare preservation. I agree.
ATheoK says:
June 5, 2014 at 5:36 pm
You’ve been shown lots of examples of not just whole herds but whole species that were wiped out. Archaic Indians wiped out at least two bison species via mass slaughter.
Over a dozen bird species, including the largest, were wiped out by the first Hawaiians. Same as in New Zealand.
Coyotes were and still are targeted just as intensely. Only the poisoning program was stopped and that was to protect harriers and eagles. Coyotes are still open hunting, year around, unlimited quota throughout America.
You are assuming things. A wolf bounty is not wolf extirpation. Wolves survived, but in very wild areas and yes, because of extensive hunting. Montana and likely nearby Idaho, Wyoming and possibly Washington never needed imported wolves. Other wild area in the Rocky and Sierra mountains are likely to have wolves remaining.
For decades, the cold weather coats with fur trimming around the hood requested and purchased by the American military used wolf fur for that trim. Why? Wolf fur does not foster hoarfrost growth from a person’s breath. Tens of thousands military coats required a lot of wolves and the bounty paid for wolf skins was very high which made it worthwhile for a hunter to track and decimate a wolf pack. But that mostly occurred during the twentieth century, not the seventeenth or eighteenth century. Modern rifles can kill a thin skinned wolf quickly.
Now about the dire wolf, a wolf larger and heavier than the gray wolf… I don’t know, but generally bigger heavier animals required very up close shots from very heavy bows to achieve sufficient penetration. Wounded animals, which would be the majority would cause significant damage before succumbing.
Man happily eats almost any meat. A piece of meat does not indicate the diet, only one inclusion for one part of the season.
Camelids and the extinct bison species still went extinct, why? Eaten?
Human scat analysis across the West identifies much rodentia in their diets but very little large mammal meats. But almost none of these locations has human evidence greater than several thousand years. Still, Mule deer, bison and mountain sheep are plentiful enough why aren’t they predominate in the scat?
One, two sites does not indicate any information beyond the one or two sites and their very incidental pieces of info. Considering how much many researchers are convinced they are looking for mega fauna extinction evidence in the few man encampments found for that time period I am surprised the information quoted is so sparse. Evidence should be overwhelming, not incidental.
ATheoK says:
June 5, 2014 at 6:09 pm
I can see you’re not a rancher or hunter. There are severe restrictions on the means by which coyotes can be killed.
You’re also wrong that wolves were not reintroduced into Montana, Wyoming, Idaho & Washington:
http://en.wikipedia.org/wiki/Wolf_reintroduction#Yellowstone_National_Park_and_Central_Idaho
As for Washington, the wolves that are now taking livestock in NE Oregon were originally introduced into SE Washington. ODFW has transmitter-collared some of them, so that you can actually watch them on line watching you & your cattle, pets & kids.
Please at least do some minimum research before commenting, since it’s clear you don’t know what you’re talking about based upon your own experience or lack thereof.
tty says:
June 5, 2014 at 11:06 am
=======================
This in itself is sufficient evidence for the overkill theory. Doubters should try to determine the statistical probability of such a combination of “coincidences.” Everywhere humans go the climate changes and wipes out the megafauna. Or every band of humans carries germs that just happen to be lethal to great big animals. Really, catastrophic global warming makes a whole lot more sense than these overkill alternatives. –AGF
agfosterjr says:
June 5, 2014 at 6:22 pm
Polynesian arrival in New Zealand & moa extinction a coincidence? I think not.
Moas hunting:
http://catdir.loc.gov/catdir/samples/cam031/89007197.pdf
No climate change, just a big change in the environment with the addition of the most successful mammalian predator of all time.
Sorry, Milodon;
You’re locked in your beliefs on this topic.
Meanwhile I am unconvinced by the arguments you’ve thrown my way; they are far from convincing.
Rampant herd slaughters leave mounds of evidence. What kind of dissolution process destroys thousands to tens of thousands of bones at a site? Lack of preservation? All bones, every site, with very few exceptions?
We have better dietary evidence from spoil piles around primitive fifty thousand year old campsites.
Isolated island communities caused some extinctions. Fairly well proven, I’m surprised you didn’t mention Easter Island; still that is a long way from proving hunter/gatherer communities cause extinctions. Isolated populations are subject to extinction for very small reasons, not just eating every one they catch.
Archaic Indians drove two bison species to extinction? I suppose you are blaming the Archaic Indians for causing the straight horned buffalo’s extinction? Not counting the mighty large lack of proof. Are you blaming them for the woods bison also?
This is a very tiring discussion with no proof, lots of assumptions based on very few claims.
When all other options are positively ruled out, then and only then does humans caused mega fauna extinction become a contender. Until proof is overwhelmingly demonstrative, that contention is in strong doubt. Especially given all of the holes in the logic, like how mega fauna died out where primitive man camp sites are not shown to exist. Or why only the biggest of the mega fauna were driven extinct, that’s a real puzzler.
Meanwhile, I am done with this topic.
ATheoK says:
June 5, 2014 at 6:38 pm
I’m not locked into beliefs. I go with the evidence. To doubt the overkill hypothesis, you have to believe, apparently purely on faith in the wonderfulness & ecological mindedness of hunter gatherers, that it’s a mere coincidence that mass extinctions of large animals happens at the same time as humans arrive on islands & continents. You also have to overlook the fact that “primitive” people slaughter far more animals than they need, because it’s easier that way or, as in the Buffalo Jump instance I provided, their beliefs tell them not to let a single prey animal escape.
Even today not just hunter-gatherers but agricultural & industrial people waste abundant resources like fish. But why should you credit my anecdotal reports?
ATheoK says:
June 5, 2014 at 6:38 pm
PS: All other options are ruled out. It wasn’t the climate. What else do you suggest? Diseases that just happen to occur whenever humans show up? What?
Wolves were never extirpated in Montana, and it is unlikely they were extirpated in nearby states with connected wilderness. Whether or not, people decided to introduce wolves.
.http://www.fws.gov/mountain-prairie/species/mammals/wolf/
About that research…
I am a hunter. There are very few ‘severe’ restrictions on how coyotes can be killed.
rifle, pistol, bow, compound bow, cross bow, snare trap, 3#-5# jaw traps…
Trapping coyote for fur is restricted to winter seasons.
Hunting coyote is usually unrestricted as to season or location, firearm choice is usually unrestricted.
There is almost no evidence. None, nada, zilch, zero; what is available are very tenuous assumptions with minimal absolute proof.
“milodonharlani says: June 5, 2014 at 6:44 pm
“ATheoK says: June 5, 2014 at 6:38 pm”
PS: All other options are ruled out. It wasn’t the climate. What else do you suggest? Diseases that just happen to occur whenever humans show up? What?”
No options are ruled out. Evidence is severely lacking. Experts use that funny word, ‘might’, when they describe the possibility.
On exactly what? I’d like enough solid proof first to even make a guess. So far every theory has it’s detractors.
The meteor strike with cataclysmic fires has more evidence than the human one; but it is hobbled by a complete lack of evidence for anything south of the north temperate zones; so it is out too.
I’ve read the disease theory and that has major holes.
No solid theories, no suggestions as suggestions are stupid till evidence becomes sufficient to postulate a valid theory.
ATheoK says:
June 5, 2014 at 6:58 pm
=================
No evidence?
1) Plenty of correlation between human arrival and extinction. Astronomically improbable coincidence.
2) Spear points found in conjunction with megafauna kills.
3) Plenty of mammoth and other megafauna bones showing signs of (human) butchering.
4) Plenty of huts built of mammoth bones, and probably covered with mammoth skins.
5) Northern Arctic island survival of mammoths out of human reach (OK, corollary of #1).
So we know humans hunted and killed mammoths, just like modern Eskimos hunt and kill whales. Now then, all we need is for the kill rate to exceed the birth rate and they’re done for. All that requires is a hunter population that depends on the big beasts, and grows until the mammoth population can no longer support them. And all the circumstantial evidence back this hypothesis up to the hilt. The evidence is even better than that for Continental Drift. –AGF
The situation in New Zealand is clear cut. with a first-time population numbering in the 10’s of thousands – in a scant 1,000 years, they wiped out virtually every edible land creature and bird with spears and stone clubs.
Piles of bones aren’t found in other mass extinction events. It’s clear that all non-avian dinosaurs died in a very short time, yet nowhere are there outcrops from the Cretaceous-Tertiary transition containing masses of bones right at the boundary. What’s remarkable to me is how many mammoth kill sites have actually been found, given the odds against their preservation.
ATheoK says:
June 5, 2014 at 6:48 pm
I said killing, not hunting of coyotes. Compound 1080 is outlawed in Oregon & M-44 in other jurisdictions. Here are leghold trap prohibitions by state:
http://www.bornfreeusa.org/b4a4_traps.php
CA F&G wants to ban predator killing contests.
cnxtim says:
June 5, 2014 at 9:26 pm
Maori could have used nets & fire, too, to kill moas & other game. Plus slings & bows & arrows.
milodonharlani, not sure about the slings, but Maori did not have bows and arrows.
Modern humans also wiped out archaic humans–H. erectus, Neanderthals & Denisovans–not necessarily by killing & eating them, but by outcompeting them, which over time leads to extinction, much as with other predator species. Also in the case of human competitors, interbreeding with them.
Steve P:
I nominate the dog, the hyena, and the bear, any of which can easily pursue and catch a man, and all of which have great endurance. A dog can lope all day.
I really enjoyed your story about the Inoca by the way.
I have often wondered about dogs. I run with mine almost every day and I must admit he can handle almost anything I have thrown at him. But I’m certain I can outpace him in a marathon type distance in the heat of a hot summer day. Some of the key differences being my ability to sweat and carry water.
Butchering tools from the Lange-Ferguson mammoth kill site:
http://www.lithiccastinglab.com/gallery-pages/2001septemberlangefergusonpage2.htm
Some beautiful Clovis points on previous page.
http://www.pbs.org/wgbh/nova/evolution/end-big-beasts.html
Edited:
Overkill proponent Gary Haynes says, “I don’t care what anybody else says, 14 kill sites of mammoth and mastodon in a very short time period is extraordinary.” Forensic studies of a cache of Clovis tools found in 2008 offers evidence for hunting now-extinct camels & horses as well.
“It’s one thing to find a campsite with some animal bones in it,” Haynes continued, “quite another to find the actual spot where an ancient hunter felled and butchered an animal—where, say, a spearpoint turns up still sticking in bone. “It’s very, very rare to find a kill site anywhere in the world,” he says. And absence of other megafauna in kill sites doesn’t mean they weren’t hunted. “There is no doubt Native Americans were eating deer and bear and elk,” Haynes says, citing several large mammals that pulled through. “But you cannot find a single kill site of them across 10,000 years.”
Good point, so to speak.
Island extinctions by man are one thing, continental or hemispheric extinctions are something else again.
My point about the dogs, bears, and hyenas was to illustrate that there are other cursorial predators with great endurance. Man’s unique characteristics are high intelligence and language, and we are deadly killers. I just don’t think the total populations of N. American tribes, themselves quite numerous, had reached the point where game populations were threatened. DeGannes noted that females outnumbered males 4 to 1 in one group he described, and the Inoca were said to be at war with a half-dozen other nations, primarily south along the Mississippi, but including also, ominously, the Iroquois, who were backed by Europeans playing off the native tribes, one against the other.
DeGannes described one situation where over the summer, various groups of 10-20 Inoca warriors were arriving at one encampment, until a total war party of 800 braves had assembled, and these set out for a successful counter-attack against the Iroquois, whom the Inoca characterized as being slow afoot, but who were very skilled in the use of the canoe for conducting raids against the Inoca, cutting their corn, and taking hostages.
Bottom line: plenty of game despite skilled hunting by native tribes whose populations were being kept in check by constant warfare with neighbors, and who ultimately fell victims to cultural disruption, disease, and political intrigue by the Europeans.