Humans may have influenced modern bear genetics far more than climate change in the last Ice Age, challenging a long-held theory, a new study says.
Scientists have long thought that the only European brown bears that survived central Europe's Ice Age 20,000 years ago lived in warm-weather southern refuges, such as modern-day Italy and Spain.
When temperatures rose again, and ice that once stretched as far south as Germany retreated, bears gradually spread into central and northern Europe, the theory holds.
The animals then became isolated in Spain, Italy, the Balkans, and Scandinavia, but their previous isolation had left a distinct genetic pattern. (See a map of Europe.)
Surprising mitochondrial DNA samples acquired from 20,000-year-old bear fossils may have turned this idea on its head.
The samples suggest large populations of bears likely roamed throughout the chilly expanses of southern and central Europe during even the worst periods of the Ice Age, according to study lead author Anders Götherström of Sweden's Uppsala University.
Not Your Average Bear?
The ancient bear DNA revealed the mixing of animals between far-flung locales, even when the ice cover was at its maximum.
(Related news: "Ancient Bear DNA Mapped -- A 1st for Extinct Species" [June 6, 2005].)
"The way we interpret it is that we [had] bears free to move around central Europe during the Ice Age," said Götherström.
The predators did not have to go south to survive, he added.
"The [existing] highly fragmented populations are what remain [after] the bear has become extinct from much of its major distribution in Europe," he said.
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