It turns out that the largest land predators alive have a host of genetic tricks to help them survive their impossibly fatty diet of seal blubber. Not only can they get rid of the lethal levels of cholesterol in their diet, they also have ways to cope with the deluge of fat, avoiding the blocked arteries that cause heart attacks in humans.
To find out how the first polar bears coped with this dramatic shift in diet, Nielsen and his colleagues sequenced the genomes of 89 polar bears and 10 brown bears, their closest relative. Out of 20,000 genes, they found 20 gene variants that were most distinct in polar bears, and which evolution has evidently favoured.
The list of genes was dominated by metabolism, heart function and coat colour. “Usually, the genes that evolve most radically in species are immune and defence genes,” says Nielsen. “What’s surprising was the focus on cardiovascular function.”
Read the full, original story: Zoologger: Polar bears evolved to eat junk food
