An international team of scientists has discovered that the female ancestor of all living polar bears was a brown bear that lived in the vicinity of present-day Britain and Ireland just prior to the peak of the last ice age -- 20,000 to 50,000 years ago. Beth Shapiro, the Shaffer Associate Professor of Biology at Penn State University and one of the team's leaders, explained that climate changes affecting the North Atlantic ice sheet probably gave rise to periodic overlaps in bear habitats. These overlaps then led to hybridization, or interbreeding -- an event that caused maternal DNA from brown bears to be introduced into polar bears.
- Ancestry of polar bears traced to IrelandThu, 7 Jul 2011, 12:37:59 EDT
- With climate changes, polar bear and brown bear lineages intertwineThu, 7 Jul 2011, 12:37:49 EDT
- Grizzly bears move into polar bear habitat in Manitoba, CanadaTue, 23 Feb 2010, 13:09:55 EST
- Ancient DNA from rare fossil reveals that polar bears evolved recently and adapted quicklyMon, 1 Mar 2010, 14:22:23 EST
- True causes for extinction of cave bear revealedTue, 24 Aug 2010, 10:29:22 EDT