There was a time when scientists thought polar bears were a simple offshoot of brown bears. But the family tree has been tweaked by DNA analysis to reveal …

(NYT— Polar bears, long thought to have branched off relatively recently from brown bears, developing their white coats, webbed paws and other adaptations over the last 150,000 years or so to cope with life on Arctic Sea ice, are not descended from brown bears, scientists report.Instead, according to a research team that looked at DNA samples from the two species and from black bears, the brown bear and polar bear ancestral lines have a common ancestor and split about 600,000 years ago.

Where exactly one species ends and another begins is hard to say when the two extant ends of a split, and presumably the origin, are all three interfertile. In this case, if the common ancestor is isolated by time, it might not annoy the average splitter too much to call it the ancestral species of brown bears and polar bears. It will however annoy creationists, then again they live in fear of all science.