Since the brown or grizzly bear (Ursus arctos) and polar bear (Ursus maritimus) diverged less than 500,000 years ago, the polar bear has evolved unique traits to adapt to the Arctic climate and ecology, such as a camouflaging coat of pigment-free fur.
When did polar bears diverge?
And polar bears diverged from brown bears between 130,000 and 650,000 years ago, with the general consensus that they first appeared in the Pleistocene, and must be at least 115,000 years, the date of the oldest known polar bear fossil.
When did brown bears and polar bears diverge?
Polar bears diverged from brown bears surprisingly recently—within the past 500,000 years, researchers report today in Cell. Previous studies suggested that the separation occurred between 600,000 and 5 million years ago.
Are polar bears and grizzly bears an example of divergent evolution?
Polar Bears’ Mysterious Origins Befuddle Scientists. Polar bears and brown bears diverged much longer ago than previously thought, new research suggests. Past estimates for this divergence came from brown bears living on the Admiralty, Baranof and Chichagof (ABC) Islands in Alaska.
Why did the brown bear evolved into the polar bear?
The bears were hungry but their paws weren’t good for walking on snow and ice, their fur wasn’t thick enough for the cold conditions and the seals could easily see them coming with their brown fur. … They are now called polar bears.