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Polar bear ancestry traced back to Irish roots

Every polar bear's ancestry can be traced back to now-extinct Irish brown bears, according to a new study.

Research suggests that the polar bear's great ancestor is the Irish brown bear, which has been extinct for thousands of years. (John MacDougall/AFP/Getty Images)

A new scientific study has found that the ancestry of all modern polar bears can be traced back to a single bear - the Irish brown bear, which has been extinct for some 3,000 years.

Published in the journal Current Biology, the genetic study found that the two separate species met and bred when climate change pushed them into each other's territory around the last Ice Age, between 20,000 and 50,000 years ago.

The researchers analyzed DNA samples from 242 bear lineages, including polar bears and brown bears, the LA Times reports. The study found that modern polar bear DNA most closely resembled that of the Irish brown bear.

The study was undertaken by researchers based at Trinity College Dublin in Ireland, Pennsylvania State University in the U.S., and Oxford College in England. 

Polar bears and grizzly bears have been found to interbreed much more recently. Climate change is bringing the two more frequently into each other's territories, the Australian reports, and they have been known to interbreed in recent years producing offspring termed 'grolar bears' or 'pizzlies'.