Evolution of Polar bears

Posted on 19. May 2014 by Rolf Stange

The evolution of Polar bears is still a matter of scientific debates. Fossils and accordingly data are scarce. Traditionally it has been believed that the species is very young, only between 100,000 and 200,000 years old. Ages putting the origin of the species back into mid or early Pleistocene times have also been suggested (see also Spitsbergen-Svalbard.com news from April 2012: Species “polar bear” older than believed so far).

A recent publication based on genetical studies now suggests that Polar bears are separated from Brown bears since 479,000–343,000 years ago, which is, within error limits, in accordance with other previous, but also quite recent, studies (see link above). Evidence is thus increasing that the evolution of Polar bears goes back to the mid-Pleistocene, the middle of the last (and still ongoing) ice age, which started about 2.6 million years ago.

The question is not only of scientific interest: If the species was as young as 100,000 years, then the current warm period would be the first challenge of this kind in the history of the species. But if the species is nearly half a million years old, as suggested in this most recent study, then Polar bears have, during their evolution, already survived more than one warm period in the past, which indicates an ability of the species to survive warmer conditions. Which is obviously not a guarantee for the survival of Polar bears through rapid changes into even warmer climates, but sheds some light on the ongoing debate of Polar bears in a changing climate.

Polar bears: their evolution probably goes several hundred thousand years back. And the photo was taken in Spitsbergen, not in the zoo.

Polar bear, Spitsbergen

Source: Cell

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