Modern polar bears descended from extinct bears from Ireland

Scientists have discovered that modern polar bears are descended from now extinct brown bears that roamed the region we know today as Britain and Ireland. It is thought that polar bears moved into this area just before, or during the last Ice Age, where they mated with female brown bears. The maternal lineage of the extinct Irish brown bear can still be traced to all modern polar bears today, according to the research published in the latest issue of the journal Current Biology . However, perhaps surprisingly, this DNA sequence does not appear in modern brown bears, but only in polar bears and the ancient brown bears that inhabited Ireland when it was experiencing much cooler temperatures. The link was established after an international research team analysed mitochondrial sequences of ancient brown bears using DNA extracted from the teeth and skeletons of 17 bears found at eight cave sites across Ireland. The scientists compared the DNA sequence of the ancient Irish brown bears with global data from prehistoric and modern brown bears and polar bears. They discovered that the remains of ten of the Irish brown bears, dated to between 38,000 and 10,000 years ago (the period spanning the last Ice Age), had the maternal line that is now seen in every modern polar bear.