Canis lupus hominis

A few days ago, I happened to mention that polar bears were actually somewhat hard to classify. They do represent a specific niche in a specific ecosystem, but they are very closely related to brown bears (European brown bears, grizzlies, and Kodiak bears are subspecies of the brown bear [Ursus arctos]). Indeed, there are populations of brown bear that are more closely related to polar bears than they are to other brown bears. (I can give you the source if you’d like. I can’t get it to link here.)

Comparison of polar and brown bear MtDNA suggests that polar bears and brown bears diverge 200,000 years ago. However, the oldest known fossil from a polar bear is 130,000 years old.

All of this evidence suggest that that a polar bear is basically a modified brown bear. It has a smaller head, larger body (although roughly equal to that of a Kodiak brown bear), sharper and more hooked claws, and a different metabolism. Only pregnant female polar bears hibernate, but all brown bears hibernate, unless they are in captivity and are fed all winter long.

Polar bears can better utilize littoral and marine environments than brown bears can. They are almost entirely carnivorous, while the brown bears are omnivores. They have become different animals– usually considered separate species.

However, their links to the brown bear as still strong enough for the two to hybridize.  In 2006, one was shot on Banks Island in the Northwest Territories, and the ephemeral and mysterious “MacFarlane’s bear,” which was documented in 1864, was probably a similar hybrid.

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I should mention here that the term polar bear is a bit of a misnomer. Today the animal is found in areas around the Arctic Ocean, but historically the bear’s range was far more southerly. In Europe they were found as far south as Bergen (Norway) and the Gulf of Bothnia, which is an arm of the Baltic Sea.

In Sea of Slaughter, Canadian author Farley Mowat contends that the polar bears had an extensive southerly range in North America. The bears were common in the Gulf of St. Lawrence. A bear was killed in the Gulf of Maine in the eighteenth century, and supposedly one was killed in Delaware Bay in the seventeenth century. (Take that last one with a grain of salt.  Albino black bears are not unknown).

To bolster his claims, Mowat points to a large population of polar bears that were found far to the south of Churchill, Manitoba, on the same line of latitude as the city of Calgary. The bears had been undiscovered,  but they were utilizing both the land and sea for food.

Because of Mowat feels that they are a more southerly species, he no longer calls them polar bears. In the text, he calls them “white bears” or “water bears.” I think that this is a pretty fair assessment.

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Now, the polar bear is threatened by climate change. It no longer can range across the ice in the Arctic Sea for as many months out of the year as it once did. As a result, polar bears are left stranded and hungry for more months and weeks out of the year.

One wonders why they don’t start foraging like brown bears do, eating what they can find.

However, brown bears learn their foraging habits from their mothers. The knowledge of how to eat certain foods and when they are available is passed on through the generations.

Polar bear mothers have taught their cubs how to live on seals on the sea ice. That is the knowledge they pass on.

When that opportunity disappears, the bears have no way of adapting in the short term.

However, I think it will be just a matter of time before some polar bears figure out how to forage on the land. Hunger is a powerful motivator, and all bears seem able to utilize new food sources all the time.

My guess is it won’t be long before they start foraging like brown bears.

Over the generations, these bears will gradually evolve to be like brown bears again, which may be further facilitated by crossbreeding.

Then the reason for them to be different from brown bears will disappear. They will gradually meld into the brown bear soup, and they will be gone.

So the likely future of the brown bear is for it to return to its past.