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Home* News and Stories → Evo­lu­ti­on of Polar bears

Evo­lu­ti­on of Polar bears

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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last modification: 2014-07-01 · copyright: Rolf Stange
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