Recent DNA studies suggest the polar bear is a much older species than previously thought. A study in the magazine Science says the polar bear split from its ancestor, the brown bear, about 600,000 years ago. Earlier, it was thought that the polar bear species was 150,000 years old, which suggested that the polar bear adapted very rapidly to Arctic life.

The U.S. Fish and Wildlife Service currently lists the polar bear as a threatened species in the Endangered Species Act because their survival is at risk due to global warming. The loss of Arctic ice poses a risk to them since they spend more of their lives in this habitat.

Dr. Frank Hailer of the German Biodiversity and Climate Research Center in Frankfurt led the international study that analyzed genetic information from the cell nucleus of more than 40 brown, black and polar bears. Dr. Hailer says this information sheds new light on conservation issues.

“It fundamentally changes our understanding of polar bears and their conservation today,” he said in an interview with BBC News. “They have survived previous warm phases but they carry scars from these times – they must have been close to extinction at times.”

The latest findings say the polar bear evolved in the mid Pleistocene era, about 600,000 years ago. This changes its evolutionary history a bit, indicating that the bear would have had more time to colonize and adapt to life in the Arctic. It also suggests that it lived through various cycles of warming and cooling. But its lack of genetic diversity would mean that changes in the environment, such as warm phases, led to dramatic falls in population numbers at times.

The report in Science elaborates that the current state of the environment could be particularly dangerous for the bears, saying that “Although polar bears have persisted through previous warm phases, multiple human-mediated stressors (eg habitat conversion, persecution, and accumulation of toxic substances in the food chain) could magnify the impact of current climate change, posing a novel and likely profound threat to polar bear survival.”

Photo: NOAA's National Ocean Service

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