"We expect, though, that humans might have played a role in other regions of the world where they did overlap with woolly rhinos." "These data suggest that climate change, and not humans, was the main reason why this particular species went extinct in present-day Europe," Shapiro said. In the case of the now-extinct woolly rhinoceros, the scientists found that in Europe the ranges of humans and woolly rhinoceros never overlapped. "Even where we didn't find evidence that humans were using the animals, if they lived in the same place and at the same time, humans could have had some influence on whether the animals survived or not." "For example, in locations where animal bones had been cooked or converted into spears, we know that humans lived there and were using these mammals as a resource," Shapiro said. The scientists also collected climate data-temperature and precipitation patterns-from both glacial and interglacial periods, as well as archaeological data, which they used to study the extent to which early humans may have influenced the survival of these species. "With genetic data, it's possible to estimate when and how much populations were able to grow and shrink as the climate changed and their habitat started to disappear." ![]() "One source of information we used was DNA from the animals themselves," Shapiro said. To find answers, Shapiro and colleagues tested hypotheses about how, when and why the woolly rhinoceros, woolly mammoth and wild horse went extinct after the last ice age and why the reindeer, bison and musk ox were able to survive-albeit in more restricted ranges than during the ice ages. "Then after the peak of the last ice age around 20,000 years ago, their luck started to run out." "Although cold-adapted animals fared better during the colder glacial periods, they still managed to find places where the climate was just right-refugia-to survive during warmer interglacial periods. "During this time, there were lots of climate ups and downs-oscillations between long, warm intervals called interglacial periods, during which the climate was similar to what we have today, followed by long, cold intervals called glacial periods, or ice ages. "This suggests that it will be challenging for experts to predict how existing mammals will respond to future global climate change-to predict which species will go extinct and which will survive."īeth Shapiro, a biologist at Penn State University whose research for the project was funded by NSF, explained that all six of the studied species flourished during the Pleistocene Epoch-the period of geologic time that lasted from about two million to 12,000 years ago. "We couldn't pinpoint what patterns characterize extinct species, despite the large and varying amount of data analyzed," said scientist Eline Lorenzen of the University of Copenhagen, the first author of the paper. "The relative impacts of climate change and human encroachment on species extinctions really depend on which species we're looking at." "Our data suggest care should be taken in making generalizations regarding past and present species extinctions," he said. "Our findings put a final end to single-cause theories of these extinctions," said Willerslev. The results carry a message about the possible fates of living mammals as Earth continues to heat up. "The combination of approaches in this study-including the most modern molecular tools and painstaking fieldwork-sheds a powerful light on the complex interactions of humans, ecosystems and climate," said Hedy Edmonds, arctic natural sciences program director in the National Science Foundation's (NSF) Office of Polar Programs, Division of Arctic Sciences. It was the first to use genetic, archaeological and climate data to infer the population history of large-bodied ice age mammals. The journal Nature published the results of the study this week. Research led by evolutionary biologist Eske Willerslev of the Centre for GeoGenetics at the University of Copenhagen along with an international team of paleontologists, geologists, geneticists and climate modelers suggests early humans and changing climate were responsible for the extinction of some cold-adapted animals, and the near-extinction of others. The histories of six large herbivores-the woolly rhinoceros, woolly mammoth, wild horse, reindeer, bison and musk ox-are linked with climate fluctuations and human activity, especially at the end of the last ice age, scientists find in a new report. Telephone numbers or other contact information mayīe out of date please see current contact information at media This material is available primarily for archival Many, but not all, ice-age mammals went extinct due to climate change and human influences.
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