Ancient DNA suggests polar bears evolved recently
Rare fossil shows creatures are most closely related to modern-day brown bears in Alaska
By Sid Perkins
The polar bear probably evolved no more than 150,000 years ago and is most closely related to brown bears that now live in southeastern Alaska, new genetic analyses of a rare fossil suggest.
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Ursus maritimus, the polar bear, is a specialized predator that — ignoring the bears that forage for garbage in towns and villages along the Arctic coast — hunts solely on sea ice.
Several previous studies agreed that polar bears are closely related to brown bears but provided widely divergent answers about when polar bears first evolved, with estimates ranging between 70,000 and 1 million years ago, says Charlotte Lindqvist, an evolutionary biologist at the University at Buffalo in New York. Now, genetic analyses of material from a fossil first described two years ago narrow the window when the huge white bears first appeared, Lindqvist and her colleagues report in a paper to be published in the Proceedings of the National Academy of Sciences.