What caused Ice Age mass extinctions?

Scientists have answered one of the most contentious questions in history – was it climate change or the presence of humans which caused extinction of some of the most iconic Ice Age mammals?

An interdisciplinary team of researchers from over 40 academic institutions analysed ancient megafauna DNA, climate data and the archaeological record and concluded that both were to blame.

“Our findings put a final end to the single-cause theories of the Ice Age extinctions, and suggests that care should be taken in making generalisations not just regarding past and present species extinctions but also those of the future,” said Professor Eske Willerslve from the Centre for GeoGenetics at the Natural History Museum, University of Copenhagen.

“The impact of climate change and human encroachment on species extinctions really depend on which species we’re looking at,” he said.

For example, humans played no role in the extinction of the woolly rhino or the musk ox in Eurasia – their demise can be blamed on climate change alone. However, they are responsible for the extinction of the wild horse and bison in Siberia.

Researchers, however, still cannot explain what caused the extinction of the woolly mammoth, or why reindeer remain largely unaffected by ether factor.

“We do find that climate change has been intrinsically linked with major megafauna population size changes over the past 50,000 years, supporting the view that populations of many species will decline in the future owing to climate change and habitat loss,” said Eline Lorenzen, lead author of the study published in Nature.

The authors found no clear pattern to distinguish species that went extinct from those that survived, suggesting it will be difficult for expert to predicts how existing mammals will respond to future global climate change.

“This work shows considerable risks we run with future climate change,” said co-author Professor Paul Valdes from the School of Geographical Sciences at University of Bristol. “The combination of climate change and habitat pressure will make it very difficult to anticipate future changes.”

Source