Where did polar bears come from?
Geege Schuman stashed this in Bears
As for where polar bears come from, it's complicated.
It has been long known that polar bears are indeed bears, belonging to the Ursids, the family of mammals that include brown and black bears, as well as others such as sloth and spectacled bears.
That may seem obvious. But there was, until quite recently, a long-standing confusion around the origin and relationship of one the polar bear's closest cousins; the panda, with scientists debating whether that species was a true bear at all, until genetic studies confirmed it was.
It has been difficult to determine the origins of polar bears in part because few preserved ancient polar bear remains have been discovered.
So scientists have turned to studying the genetics of bears to establish when they diverged from each other.
One study published in 2013 suggests that pandas split from the bears anything from 8 to 38 million years ago.
Black and brown bears then split into unique lineages between 1.5 and 6.5 million years ago.
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.
However, that is not the end of the story. Discrete populations of polar bears are thought to have mated and bred with populations of brown bears since.
Now-extinct brown bears that once lived in Ireland, for example, had polar bear ancestry, perhaps because past changes in the distribution of polar ice, for example, stranded polar bears or hybrids on the island.
Brown bears living on islands off the coast of Alaska also appear to have polar bear ancestry.
A study published in 2014 also found tantalising genetic evidence that bears living in the Himalaya mountains, a vast distance from the Arctic, may have derived from polar bears. This unique heritage could have produced bears that look and behave slightly different from the brown bears that usually live in the region, albeit at lower altitudes. And these odd, high-altitude bears may be the origin of the Yeti legend, speculate the scientists who conducted the study.
i was just at the natural history museum in DC and learned all about this! they had a video showing brown bears evolving into polar bears. fascinating!
The white fur is better for camouflage near ice floes?
makes sense. the museum info said that it had to do with hunting prey. the ones who managed to blend in with their environment could successfully kill seals, the browner ones, not so much. so as evolution would have it, the lighter bears managed to eat and... boom! polar bears.
hahaha! but awwww.... :(
Beneath this fur, polar bears have black skin, which absorbs sunlight and helps keep the bears warm. Even more surprising—polar bears aren’t actually white! Polar bear fur is clear, with no pigment, but refracted light makes it appear white. Depending upon the lighting, polar bears can look yellow, brown, or even grey. (So it's like a coat of invisibility!)
that is cool! clear hair. i'll bet it dyes really well...
I suppose if they walk around in mud (or blood!) they can get a reverse-ombre effect.
"i want pink!"
YES!!! swoosh! nailed it, adam!!
i'm going to make that into my desktop wallpaper right now.
ha! look at that! i guess so... somewhere!
i just shouted "pink" first. i had no idea pink polar bears already had a following!
Polar bear in a girls of lavender:
hahaha! please don't edit it, adam! it would make a great band name! :)
Done and done:
*dammit iPad autocorrect, you had ONE job!
oh yes, i see it on the keys... girls and field are very close to one another!!
Surprisingly close. I'm sure that has led to some embarrassing texts!
PW is your external brain. So is everything else. :)
These days PW really is my external brain.
Interesting experiment to make it all public like this instead of private like Evernote.