Polar bear ancestors came from Ireland
8 Jul 2011
It's a long way from the Arctic to Tipperary, but scientists have discovered polar bears can trace their family tree to Ireland. Genetic evidence shows they are descended from Irish brown bears that lived during the last ice age.
Modern polar bears share a distinct DNA sequence, passed down the female line, with their now extinct brown ancestors. However, the same DNA fingerprint is absent from other species of brown bear alive today.
It is thought the link arose from interbreeding between prehistoric polar bears and female brown bears when their paths crossed as the Irish climate cooled.
Scientists made the discovery after analysing DNA in mitochondria - energy-producing structures within cells - that are only passed from a mother to her offspring.