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Climate Change Drove Extinction of Ice Age Mammals, Study Says

By Makiko Kitamura (Bloomberg) - November 2, 2011

The extinction of some Ice Age animals, such as woolly mammoths and Eurasian musk oxen, resulted mainly from climate change over the past 50,000 years, suggests a new study published today in the journal Nature.

Researchers used genetic data from fossils of six megafauna, or large mammal, species — woolly rhinoceros, woolly mammoth, horse, reindeer, bison and musk ox — as well as radiocarbon-dated objects associated with human habitats in Eurasia to map out locations of humans and animals over time. The scientists, led by Eske Willerslev, a biology professor at the University of Copenhagen, found little geographic overlap between humans and woolly rhinos in Siberia after the peak Ice Age period, about 20,000 years ago.

The findings add new evidence to the scientific debate about what caused the extinction of megafauna. Researchers at the University of Wollongong and the University of Adelaide wrote in the journal Science last year that humans caused animal extinctions in Australia. A 2009 study, also published in Science, found that mammoths and mastodons began dying out 1,000 years before humans arrived in North America.

“For the woolly rhino, we can definitely exclude, based on our data, that humans had anything to do with their extinction because they simply weren’t in the same areas,” Eline Lorenzen, a population genetics researcher at the Danish university who worked on the study, said by phone.

Woolly Mammoth

The evidence is less conclusive for the woolly mammoth, remains of which were found in 35 percent to 40 percent of all European and Siberian sites inhabited by humans in the Paleolithic period, 50,000 years ago to 12,000 years ago, the researchers said.

A separate analysis using data on temperature and precipitation showed that megafauna population sizes correlated with climate change.

A combination of climatic and human influences may be responsible for the demise of wild horses and ancient bison, whereas reindeer remain relatively unaffected by these factors.

Genetic data was gathered from bone excavations in Siberia and western Canada, as well as from those stored in natural history museums in Russia, France, Germany and Spain, Lorenzen said.

“Our study demonstrates the importance of incorporating lessons from the past into rational, data-driven strategies for the future to address our most pressing environmental challenges: the ongoing global mass-extinction of species and the impacts of global climate change and humans on the biodiversity that remains,” Willerslev wrote in the published paper.