A few thousand years ago, the world was a very different place. An ice age was raging, and with it came all sorts of weird and wonderful animals; like the famous woolly mammoth in Europe1.
Then humans arrived and it all changed. Most of those impressive species of megafauna went extinct.
Is there a connection between the two? Archaeologists have been debating back and forth for decades. Many note the convenient timing between the two events. For instance, every species Australian megafauna went extinct a few thousand years after humans arrived2.
But new research suggests that – at least in Europe – humans are innocent of megafauna murder1. But does their argument hold up?
Responsible killers avoid the mammoth
Essentially, this new research tried to figure out how often humans and megafauna would meet. After all, we’re going to have a hard time driving the mammoth extinct if they live thousands of miles away.
Figuring this out had two main steps. First, the looked to see where ancient humans liked to live in ice age Europe. By examining the palaeoenvironment of thousand fossil sites, they built up a good model of the sorts of areas people tended towards. Next, they repeated the same basic method with the various species of megafauna, both living and extinct, present in Europe at this time1.
Armed with this information, they could compare the two datasets. Which animals shared our preferred environment?
It turns out many species of large mammal did live alongside us, though this is in part simply because we all lived in such a large area. Surprisingly few actually preferred the exact same territory as us. Instead, there was some overlap between humans and other species, but most of their range was outside our habitat1.
For example, the mammoth – as the graph above shows – was perfectly capable of living in Northern Europe, outside the reach of humans. So whilst some mammoths would be forced to co-exist with humans, much of their population could survive beyond our reach.
Which is probably for the best because the mammoths that did live with us often didn’t do too well3.
So what did humans hunt?
Many of the classic ice age species, like mammoths and bison, had vast chunks of territory outside the reach of humans. So if they were relatively safe from us, which species were we hunting?
Well, the answer changes over time. As the local environment changed (and our ability to adapt to it) we moved into different areas with different animals1.
Nevertheless, at almost every point the animals which were stuck with us are those that are still alive today. Animals like horses, boar, reindeer, and red deer1.
Based on all these charts and statistics the researchers concluded humans probably weren’t responsible for the extinction of mammoths and other ice age European animals. We’d encounter them less frequently (as more of their population was living outside their territory) and even when we did hunt our local mammoths, there were still regions outside our reach they could survive1.
However, this creates a bit of a paradox. The species which were more vulnerable to human-caused extinction, like reindeer, are still alive. How were they able to survive the full force of human hunters?
The researchers suggest that maybe the hunters took steps to stop their prey from going extinct. Over the ice age the diversity of human diets increases, perhaps to make sure they weren’t too reliant on any one species. Plus, climate change meant the most available species changed often. This would help give some species respite and recover their numbers1.
All in all, they suggest that ice age humans were “well-behaved killers”1.
A worldwide pattern of extinction
Now, at this point, you might be feeling quite positive about these ancient humans. After all, it seems that they were responsible hunters who took steps to preserve their local environment. They were the worlds first environmentalists!
Unfortunately, this is the exception rather than the rule.
Whilst humans were being well behaved in Europe, our species was also expanding into Asia, Australia, and later, America. Most of those continents were devastated by the arrival humans, with massive chunks of their megafauna going extinct2.
The fact that humans were so murder-y elsewhere suggests that the survival of species in Europe wasn’t deliberate. We didn’t go out of way to preserve the mammoth. They were simply fortunate enough to be living out of our reach. Those species which were within our reach got chances to escape for a bit, thanks to climate change.
But in other places animals weren’t as lucky. They didn’t have refugia or a respite due to climate change. And so we killed them all. I assume we would have done a similar thing with the mammoth if circumstances allowed it.
Humans, it seems, have always been bad news for the environment.
- Carotenuto, F., Di Febbraro, M., Melchionna, M., Mondanaro, A., Castiglione, S., Serio, C., Rook, L., Loy, A., Lima-Ribeiro, M.S., Diniz-Filho, J.A.F. and Raia, P., 2018. The well-behaved killer: Late Pleistocene humans in Eurasia were significantly associated with living megafauna only. Palaeogeography, Palaeoclimatology, Palaeoecology, 500, pp.24-32.
- Koch & Barnosky, 2006. Late Quaternary Extinctions: State of the Debate. Annual Review of Ecological Systems, 37, pp.215-250.
- Demay, L., Péan, S. and Patou-Mathis, M., 2012. Mammoths used as food and building resources by Neanderthals: Zooarchaeological study applied to layer 4, Molodova I (Ukraine). Quaternary International, 276, pp.212-226.