What polar bear’s diet may tell us about how our bodies can handle fat
Scientists show genetic changes have allowed Arctic predator to be both obese and healthy
When it comes to healthy eating, polar bears break all the rules. They eat mostly fat, but they don't get heart disease the way humans would. And the reason lies in their genes, US scientists have reported in the journal Cell.
Some speedy evolutionary tricks, particularly in the genes which handle how fats are metabolised and how fats are transported in the blood, have allowed polar bears to survive in the Arctic, the scientists said.
And it all happened within the last 500,000 years, after the polar bear split from its cousin, the brown bear, according to research that compared the two animals' genomes.
Scientists found that polar bears are much younger than previously thought, with past estimates of the divergence time between polar and brown bears ranging from 600,000 to five million years ago.
"It's really surprising that the divergence time is so short," said Rasmus Nielsen, a University of California Berkeley professor of integrative biology and statistics.
"All the unique adaptations polar bears have to the Arctic environment must have evolved in a very short amount of time," he said.
It's unclear what drove polar bear to evolve into a separate group from brown bears, though it coincides with a warm interglacial period that could have encouraged brown bears to venture further north than they had in the past, researchers said.