- A new study estimates polar bears split from brown bears between 4 million and 5 million years ago.
- Recently, wild hybrids and second-generation offspring have been documented in the Northern Beaufort Sea of Arctic Canada.
- This complicated history may explain why other research has estimated a much younger age for polar bears.
Polar bears' past may echo their future, indicates a genetic study that finds the white-furred, sea ice-dwelling bears interbred with brown bears long after the two species separated as much as 5 million years ago.
Climate change likely drove this mixing among bears, writes the research team, noting there is evidence this is happening again.
"Maybe we're seeing a hint that in really warm times, polar bears changed their lifestyle and came into contact, and indeed interbred, with brown bears," said study researcher Stephan Schuster, a professor of biochemistry and molecular biology at Pennsylvania State University, and a research scientist at Nanyang Technological University in Singapore, in a statement.