Megafauna Extinction: Did Humans or Climate Kill Off the Mammoths?

Stanford biologist Elizabeth Hadly recaps a debate among biologists over whether prehistoric megafauna like mammoths, giant sloths and saber-toothed cats became extinct due to overhunting by humans, or by a combination of hunting and a changing climate.

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Stanford biology professor Elizabeth Hadly's research in the far reaches of the globe from India to Patagonia to Southeast Asia addresses the issues of what determines and maintains vertebrate (especially mammal) diversity through space and time and how that diversity is influenced by the environment. - California Academy of Sciences

Elizabeth Hadly is Associate Professor, Department of Biological Sciences and Departmen of Geology and Environmental Sciences, Stanford University. The research of Elizabeth Hadly probes how perturbations such as climatic change influence the evolution and ecology of Neogene vertebrates.

Professor Hadly's field research involves excavation of finely stratified Holocene paleontological sites and collection of modern specimens in western North America and Patagonia. Construction of a state-of-the-art ancient DNA laboratory has made possible the study of genetic structure of populations through time. Laboratory work includes morphometric and molecular analyses with the intent to extend the level of investigation down to the population and genetic levels. Ongoing projects at the macroecological scale include the study of the ecological and evolutionary factors influencing biological diversity through a comparison of temperate terrestrial vertebrate faunas in North and South America.

[TonyTrupp]

Mammoths and other megafauna lived through 20 or so previous ice ages before this last ones, some of which got just as warm as in the holocene. And yet they survived those extreme swings in climate. Until this last one when humans started creating more spear points. That alone should indicate humans were likely to be a primary driver. Yes, there was the rapid cooling period of the younger dryas, interrupting the glacial retreat, which also correlated with a pulse of extinctions within north america. But the younger dryas did not have much impact at all in south america, where the cooling and resumed warming was much more gradual and not nearly as extreme. And yet we still see similar extinctions in south america, also correlating with humans making more advanced spear tips there too. That again points to humans and not climate being the primary driver. Then there’s the fact that many of the megafauna survived thousands of years beyond the younger dryas, even in north america. Giant sloths for instance finally went extinct thousands of years later on islands in the caribbean, around the same time they become populated by humans. Mammoths lived on wrangel island until around 4000 years ago, which wasn’t populated by humans. If climate were the primary driver you likely wouldn’t see them surviving much longer only on these islands. She mentioned australia. That’s another example of humans arrival corresponding to the disappearance of megafauna, and it occurred as glaciers were still advancing, not receding. So a warming climate can’t be blamed on those extinctions. Humans are the common factor in all these cases.

[WoebringerofDoom]

people often use the wild west killing of buffalo to explain how humans killed all the big prehistoric anmials, but i don't think that to be the case.

[guy]

I’m not a scientist and I’m sure this woman knows a lot more than I do. However one thing that I’ve come to realise is that maybe the mammoth steppe disappeared because the mammoth went extinct not the other way round. I mean there are multiple examples of keystone species around the world creating habitats to the benefit of themselves and other species. That could possibly explain some of the other extinctions as well that don’t have hunting evidence that could have died due to their dependence on the mammoth steppe and therefore the mammoths (this could include predators of the mammoth as well)

[morrisvalentneflatlander]

If you're saying humans are responsible for mega fauna extinction. It breaks down like this 99.75% climate .25% humans mammoths were highly specialized to their environment and unable to adapt to change. I hunt there is a reason humans domesticated animals. Hunting is extremely difficult with a rifle I can't imagine what it's like with a stone tipped spear.

[bluenail]

Wasn't there a comet impact on Eastern Carolina? Or on the glaciers to the north?

[SG-cttb]

Thank you Elizabeth. The overkill theory always seemed so off to me.

[HalfFullYeah]

Mammoths'R back?!

Wife, bring me my bow!

[oobrocks]

Overkill is the only solution. The idea of "where's the bodie, " is a stupid pt. They died somehow so "where's the bodies, " no matter how they died

[oobrocks]

The climate was getting warmer which most animals would like. More plants for plant eaters so more food for predators

[comitcrafter]

Listen to randle Carlson and graham handcock they have great data concerning the ice age and ancient cultures. good stuff

[TheFixIsIn-fejy]

I don't think they died, I think they are the elephants, and kangaroo's we have now. I don't think the human population was very many if any during Megafauna period, 60, 000 years ago the human population just began to grow after humans learned to farm for food, Then we began to have forest depopulation, and still do. I think there where massive Volcano action starting 50 Ma and it caused the ice age that we still haven't fully recovered from. Washington state had the last Missoula flood 13, 000 to 15, 000 which left the bad lands, or scab lands when the ice sheet broke and the ice dam caved sending vast amounts of rushing water across Idaho, Washington state, Oregon, so the earth was still under the ice age 13, 000 years ago. dough if the human population was thriving during that time.

[jcgfranco]

Clovis wasn´t first. so they didn´t drove big mammals to extinction. It was a rapid extinction, now it is far more plausible the younger dryas impact in Greenland.

[buzzlightyearandco]

When is the cloning thing gonna happen?

[beastmaster]

I’m gonna say both
The climate changed and the ice age beasts slowly died off and humans dealt the final blow.

[CLAudio-pnqf]

Never mind that there's overwhelming evidence of a massive asteroid impact at that same time.

[anubis]

@geezzerboy They are dated based on things at the same layer. My gf is an archeologist so its a science slip of the tongue, happens to the best in science.

[BigOlRub]

Well we did manage to kill off the dodo bird. So humanity overkilling mammoths is very plausible. You guys should also keep in mind that even today, over poaching could cause the extinction of many endangered species, and the only thing stopping these extinctions are those of us who decided to safeguard the animals. Mammoths were slow and massive targets, and just like elephants, they are slow to reproduce. It is very likely that humanity over hunted mammoths, just as how it's very much a fact that we over hunted whales and other animals into near extinction.

Don't knock off the human overkill hypothesis just yet, instead we should try to create more safeguards so that overkills wont happen.
Just look at how our species has grown. We are arguably super apex predators but our numbers don't reflect the smaller number that apex predators should have. We are an unnatural species, if any other animal were to be as dominant as we are they would have caused catastrophic changes to the habitats. The only thing that's stopping us from destroying existing habitats is our ability to self control and provide for ourselves. And we need to focus on this really, our self control and discipline is what will change the world for the better. If we choose to be more serious in preserving nature, then theoretically we can still fix the damage that we've caused to it.

I'm not kidding, our great filter may just be on the horizon. And our inability to adapt will be our downfall, imagine if we never moved away from whaling and whales have gone extinct? Wouldn't the ocean's ecosystem go crazy? We might have even saved ourselves from extinction because of it. We are the odd invasive species that could potentially ruin ecosystems, agriculture might have legit saved the world from a mass extinction.

Scary enough, if ever agriculture fails and we resorted back into hunting and gathering. A lot of humans will die, but we would still kill off a lot of other species to avoid the unavoidable mass starvation. We will surely bring forth a mass extinction event, so pray it never happens.

[douchebagpatrol]

a meteor that hit greenland killed them off u can c the crater covered by ice on google maps
god i am a fucking

[marsCubed]

@gajxo Yes we do need to bring mammoth back, they taste great ! and their tusks make good shelters.
Scientists hope to find enough usable woolly mammoth DNA to implant it into unfertilised Asian elephant eggs. mammoth mtDNA is known so ancestry can be traced to Asian elephants as closest relatives.. or in Indian elephant DNA could have mammoth DNA replace specific differences.
Either way, expect mammoths some time in the future.