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DNA from a polar bear jawbone has revealed the Arctic coinage first grow about 150,000 years ago , scientists foretell today .
It has been known that polar bears develop from brown bear , but until now , it was n’t clean-cut when this happened .
Here two polar bear cubs snuggle up. The polar bears, which evolved from brown bears, originated some 150,000 years ago, according to genetic analyses of a polar bear fossil.
The discovery was enable by the rarified jawbone find on the Norse island of Svalbard in 2004 . Very few earlypolar bearfossils have been recovered so far , so their evolution has not been well understood .
" This really gave us a unique opportunity to endeavor to count on the origin appointment of the species , " said study leader Charlotte Lindqvist of the University of Buffalo . " diametrical bears as a metal money are reasonably untested and probably evolved fairy late . "
The mandibula , which is between 110,000 and 130,000 years honest-to-goodness , provide the Florida key to the polar bears ' past , because it offered a sample distribution of genetic fabric . The researchers practice into a tooth on the off-white to extract mitochondrial DNA , which is deoxyribonucleic acid from the energy - produce part of the cell call mitochondria . The scientists then sequenced this desoxyribonucleic acid and compared it with the DNA of modern diametric bears , and modernbrown bearsfrom Alaska ’s Admiralty , Baranof and Chichagof Islands , which are the polar bear ’s closest relation .
" We had to compare modern polar bears with this ancient polar bear and also the skinny relatives of polar bear in decree to reconstruct the family trees to understand their development , " Lindqvist told LiveScience . " Polar bear actually originated from within chocolate-brown bear . We found that this ancient polar bear is positioned almost like a shot at the splitting stop between polar bears and brown bears – very closely to the uncouth ascendent . "
In fact , the polar bear genome the researchers derived is the oldest mammal mitochondrial genome ever to be sequenced . The work was made potential by the most recent genome sequencing technologies , Lindqvist said .
Polar bear are an extremely specialized species . Whereas browned bears are more generalized and can survive in a salmagundi of home ground , polar bear evolved to take advantage of a very specific ecological niche .
" Polar bear are very specialised to the habitat they live in on the sharpness of the Arctic sea methamphetamine hydrochloride , " Lindqvist said . " They feed on a few coinage of cachet and are very adapted to that home ground . "
This specialization could make it more unmanageable for them to conform to the changing mood . The species evolved to live on sea ice , and each year of late there is less and less of it .
" As the arcticsea frosting is reducedthe polar bear very well may lose lots of home ground , " Lindqvist said . " If this movement proceed we can only imagine that this must have a striking effect for their uphold endurance . Whether icy bear in the future will be able to adapt to warm climates is strong to say . "
The inquiry was detailed in the March 1 result of the journal Proceedings of the National Academy of Sciences .
