A 'smoking gun' on the Ice Age megafauna extinctions

Gut content

It was climate that killed many of the large mammals after the latest Ice Age. But what more specifically was it with the climate that led to this mass extinction? The answer to this is hidden in a large number of sediment samples from around the Arctic and in the gut content from permafrozen woolly rhinos, mammoth and other extinct ice age mammals.

It is a bit of a shift in paradigme Willerslev and co-workers publish in this week's edition of the journal Nature. The common image of a light-brown grass-steppe dominating the northern hemisphere during the Ice Age does not hold any longer. The landscape was far more diverse and stable than today, and big animals like woolly rhino and mammoth fed on grasses and particularly on protein-rich forbs. But at the Last Glacial Maximum 25,000 – 15,000 years ago, at a time when the climate was at its coldest and driest, a major loss of plant diversity took place. The animals barely survived.

After the Ice Age ended about 10,000 years ago it became warmer again. After the large reduction of plant diversity during the Last Glacial Maximum another kind of vegetation now appeared. One of the key food sources of the large mammals– the protein-rich forbs – did not fully recover to their former abundance. This likely proved fatal for species like woolly rhino, mammoth, and horse in Asia and North America. Even though it became warmer again after the end of the Ice Age the old landscapes did not return.

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