Munch Lab

No magic bullet explains Ice Age megafauna extinctions

mammothWas it humans or climate change that caused the extinctions of the iconic Ice Age mammals (megafauna) such as the woolly rhinoceros and woolly mammoth? For decades, scientists have been debating the reasons behind these enigmatic Ice Age mass extinctions, which caused the loss of a third of the large mammal species in Eurasia and two thirds of the species in North America. In an extensive, inter-disciplinary research collaboration, involving over 40 academic institutions around the world, we have tried to tackle the contentious question in the biggest study of its kind. As so often in science the answers turn out to be far more complicated than imagined. The study, published online today in Nature reveals that neither climate nor humans alone can account for the Ice Age mass extinctions. Using ancient megafauna DNA, climate data and the archaeological record, the findings indicate dramatically different responses of Ice Age species to climate change and humans. For example, the study shows that humans played no part in the extinction of the woolly rhino or the musk ox i Eurasia and that their demise can be entirely explained by climate change. On the other hand, humans aren’t off the hook when it comes to the extinction of the wild horse and the bison in Siberia. Our ancestors share responsibility for the megafauna extinctions with climate change. While the reindeer remain relatively unaffected by any of these factors, the causes of the extinction of the mammoths is still a mystery. Despite the unparalleled amount of data analysed in this study, we find no clear pattern distinguishing species that went extinct from species that survived, suggesting that it will be extremely challenging for experts to predict how existing mammals will
respond to future global climate change.

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