Polar bears and brown bears diverged much longer ago than previously thought, new research suggests.
Past estimates for this divergence came from brown bears living on the Admiralty, Baranof and Chichagof (ABC) Islands in Alaska.
But according to a new study, ABC Island bears are actually the result of mating between brown bears and polar bears in the last several thousand years, making the population useless for determining polar bear roots.
"If we really want to understand the evolution of brown bears and polar bears , we should ignore them [the ABC bears]," said study co-author Beth Shapiro, an evolutionary biologist at the University of California Santa Cruz. "They are a special case and they're not going to tell us anything about the origin of the polar bear."