If there were no people in Europe, large animals such as mammoths and cave bears would be thriving there in even greater numbers today than 120,000 years ago.
That is the conclusion of a modelling study based on fossil and climate data. It also shows that the loss of megafauna has had a massive effect on Europe鈥檚 ecosystems.
Many of the really large animals around the world, from the giant sloth of South America to Haast鈥檚 eagle in New Zealand, have gone extinct over the past 50,000 years or so, with the extinctions often coinciding with the arrival of modern humans. Yet there is still debate about the causes, with some researchers blaming changes in the climate during or after the last glacial maximum, which occurred around 30,000 to 10,000 years ago, rather than overhunting.
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These debates often focus on a single species such as the woolly mammoth. at Aarhus University in Denmark and his colleagues have instead tried to work out what Europe鈥檚 ecosystems would be like if modern humans hadn鈥檛 arrived on the scene.
The team used a combination of computer modelling and records of fossil finds and the past climate to work out the most likely distribution in Europe of nearly 50 large animals during the previous interglacial period, around 130,000 to 120,000 years ago, and also what this would be today without any human intervention.
The species included the straight-tusked elephant, the cave bear, the woolly mammoth, the woolly rhino and the giant rhino, all of which are now extinct. The team also looked at species such as the red deer and the European beaver that survive in the region to this day, as well as those such as the hippo that are extinct in Europe but survive elsewhere.
There were Neanderthals in Europe during the previous interglacial period, says Davoli, but their numbers were so low that they are aren鈥檛 thought to have had a major impact on the wildlife beyond the vicinity of their habitations. Only the arrival of Homo sapiens can explain why most of the megafauna were wiped out, says Davoli.
It is possible that some species went extinct because of climate change during or after the last glacial maximum, he says, but this can鈥檛 explain why so many species went extinct all at once. During previous changes in the climate, most species survived the transitions, says Davoli 鈥� it is only the last one where there is a drastic difference.
The loss of so many megafauna means that ecosystems we regard as 鈥渘atural鈥� today are quite unlike those in the past, says Davoli. For instance, forests wouldn鈥檛 have been continuous but much patchier, with more clearings created by large animals.
鈥淭hat was the state of our nature for hundreds of thousands of years or even millions of years,鈥� he says. 鈥淚t鈥檚 pretty a big gap to fill with rewilding strategies.鈥�
鈥淭he study adds to the evidence that humans have been an altering force on megafauna,鈥� says at the University of Adelaide, Australia, who has studied what drove the woolly mammoth extinct.
But its reliance on modelling to fill in the gaps in our knowledge means there is quite a bit of uncertainty about the study鈥檚 conclusions. 鈥淚t still does not eliminate climate as an important and co-occurring causative factor,鈥� says Fordham.
bioRxiv
