Fossils of polar bears are uncommon. [12][15] The oldest known fossil is a 130.000- to 110,000-year-old jaw bone, found on Prince Charles Foreland,
Norway, in 2004,120)[1) Scientists in the 20th century surmised that polar bears directly descended from  population of brown bears, possibly in eastern
Siberia or Alaska.[12][15] Mitochondrial DNA studies in the 1990s and 2000s supported the status of the polar bear as a derivative of the brown bear.
finding that some brown bear populations were more closely related to polar bears than to other brown bears, particularly the ABC Islands bears of
Southeast Alaska.[20][21][22] A 2010 study estimated that the polar bear lineage split from other brown bears around 150,000 years ago./20;