Older Than We Thought!
New evidence suggests that polar bears first appeared about five million years ago, making them much older than previously thought. They diverged from brown bears and underwent a series of evolutionary changes in order to survive in the harsh conditions of the Arctic—adaptations from the shape of their body to keener senses, white fur, and sharper teeth.
The findings indicate that polar bears evolved over a long time frame to a life of hunting seals and surviving extreme cold, a life quite different from terrestrial brown bears.
Interestingly, the genome evidence shows that after brown bears and polar bears separated, there were periods when they came into contact again. The new study also reveals surprisingly little genetic diversity in today’s polar bears, suggesting bottleneck periods, probably during warm periods, when their numbers were severly reduced.
What does this mean in the face of the current arctic warming now taking place? First, the longer evolutionary period shows that polar bears won’t be able to adapt to changing sea ice conditions within a mere one hundred years. And although the longer time frame means that polar bears survived previous warm periods, the temperatures reached in the Arctic if we continue on our present greenhouse-gas-warming course will be unlike anything polar bears have survived before.
Read more via Polar Bears International.