An international team of scientists has discovered that the female ancestor of all living polar bears was a brown bear that lived in the vicinity of present-day Britain and Ireland just prior to the peak of the last ice age, 20,000 to 50,000 years ago.
The research, which is led by Penn State's Beth Shapiro and Daniel Bradley of Trinity College Dublin, is expected to help guide future conservation efforts for polar bears, which are listed as threatened under the Endangered Species Act. Polar and brown bears are vastly different species in terms of body size, skin and coat color, fur type, tooth structure, and many other physical features.
Behaviorally, they are also quite distinct: Polar bears are expert swimmers that have adapted to a highly specialized, arctic lifestyle, while brown bears -- a species that includes Grizzlies and Kodiaks -- are climbers that prefer the mountain forests, wilderness regions, and river valleys of Europe, Asia, and North America.
"Despite these differences, we know that the two species have interbred opportunistically and probably on many occasions during the last 100,000
years," Shapiro said.
years," Shapiro said.
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