New genetic evidence shows polar bears withstood a very warm interglacial period 44,000 years ago. So can they survive current warming?
- An early polar bear fossil confirms that they diverged from brown bears 150,000 years ago - Polar bears were around for a previous, warmer, interglacial period.
- Though they survived that period, polar bears today face bigger threats than ever before.
Polar bears are a remarkably recent offshoot of the brown bear family tree according to the oldest DNA studied to date from a rare fossil from Norway.
The mitochondrial DNA (mDNA) from the 150,000-year-old bear fossil place it on the bear family tree very near the time when a branch of the brown bears diverged and, after a lot of rapid evolution, became the very specialized polar predator we know today.
The discovery settles some controversies about polar bear evolution, as well as raises questions about the great mammal's ability to adapt to a warming climate.
"People didn't really know where the polar bear came from," explained Schuster. "Some people said the speciation happened very, very recently, perhaps within 10,000 years."