Fossil Jawbone Hints at Polar Bear Past
Scientists have uncovered a fossilized jawbone from the sediments of an island in the Svalbard archipelago, a set of islands in the Arctic Ocean that lie approximately half-way between Norway and the North Pole. The jawbone shares a convincing resemblance to that of a polar bear (Ursus maritimus). If it is indeed the remains of a polar bear, it represents the oldest known fossil record of the species. The research team, lead by Professor Olafur Ingolfsson from the University of Iceland, estimates the age of the fossil is at least 100,000 years old. This means the polar bear, thought to be a recently evolved species, has a longer evolutionary past than previously suggested.
Polar bears share a recent common ancestor with brown bears (Ursus arctos), their closest relative. The two species are believed to have diverged during the Upper Pleistocene (126,000–10,000 years before present). During that period, a population of brown bears in the far north of their range is thought to have been isolated by glaciers. The population changed over time and individuals better adapted to the harsh polar environment survived and reproduced. Over many generations, the isolated brown bears had evolved into polar bears.
This narrative suggests how the changes progressed, but the details of polar bear evolution remain obscure because the fossil record is sparse when it comes to the polar bears of the past. This is in no small part due to their habitat. The remains of polar bears would likely be scavenged or sink to the bottom of the Arctic Ocean before they had a chance to become preserved in the ice. Despite the lack of fossil evidence showing the progression of brown bear to polar bear, genetic analysis of the two present day species has yielded solid evidence that they are closely related.
Find out more:
- Ancient Polar Bear Jawbone Found (BBC News)
- Jawbone from Ancient Polar Bear Discovered (Natural History Museum)
- Polar Bear Evolution (Polar Bears International)
- Evolution of Polar Bears (Phil Candela, Laboratory for Mineral Deposits Research)
Photo © Nikolay Okhitin / Shutterstock.
Comments
“Polar bears are thought to share a common ancestor with brown bears (…)”
Good. And they are also thought to share common ancestors with monkeys, squids, dandelions…
And whom did you benefit by saying that, Paleofreak? Have you proven yourself superior? Why? If you have nothing useful to say, don’t stoop to say anything. It is unflatteringly rude. Perhaps find something to do, rather than pick apart what others are doing that is not harming you.
Thank you both for commenting. I agree with ambassador - I found the comment by Paleofreak off-putting. At the same time, Paleofreak did bring up a good point, regardless of the manner in which it was presented. The original statement was vague:
“Polar bears are thought to share a common ancestor with brown bears.”
I (hopefully) improved it, as follows:
“Polar bears share a recent common ancestor with brown bears (Ursus arctos), their closest relative. The two species are believed to have diverged during the Upper Pleistocene (126,000–10,000 years before present).”
Of course, it remains important to keep in mind that I’m not writing a dissertation here. It’s an article for a general audience. I think most readers would have understood the meaning of the former version and would have received no mis-information because of it.
That’s some interesting information. Doing the research on this must be difficult in such a harsh climate as was brought out in the article. Ironically, now that things are heating up in the Arctic, maybe more evidence about the origins of polar bears will come to light.