Ten Irish brown bears from between 10,000 and 38,000 years ago carried a distinct sequence of mitochondrial DNA, originating from a specific female brown bear, and this DNA sequence has been passed down the female polar bear line and is found in all polar bears today.
1万年から３万８０００年の間に１０頭のヒグマが特定の雌のヒグマに由来するミトコンドリアDNＡの異なるシークエンスを運び、このDNＡシークエンスが雌の北極グマの血統で伝えられ、現在のすべての北極グマに見られる。