Polar bears appear to be rewriting parts of their DNA in response to a warming Arctic, according to new research that scientists describe as both alarming and cautiously hopeful. A study from researchers at the University of East Anglia, published in the journal Mobile DNA, suggests this is the first documented case of genetic change in a mammal owing to rising temperatures. By analyzing blood from polar bears in northeastern and southeastern Greenland, researchers found that bears in the slightly warmer south showed different activity in genes tied to heat stress, aging, and metabolism compared with those farther north, per NBC News.
Lead author Alice Godden says different populations are seeing distinct sections of their DNA altered at different speeds, apparently in response to local climate conditions. She describes it as a forced genetic "rewrite"—a rapid adaptation that she calls a "desperate survival mechanism" as sea ice disappears. With warming oceans reducing the ice platforms used to hunt seals, bears are shifting toward a diet with more plants and less fat, Godden told NBC. That dietary change appears to be driving genetic tweaks related to digestion and may even be affecting the bears' body shape and composition.
The findings offer what Godden calls a "glimmer of hope," suggesting polar bears have at least some capacity to adapt quickly to climate change. But she stresses the species remains in serious trouble. There are an estimated 26,000 animals left, and projections indicate two-thirds of the population could vanish by 2050. The study, Godden says, does not lessen the extinction risk but may provide a "genetic blueprint" for how the animals can adjust—if warming can be slowed enough to give them time. And "provided these polar bears can source enough food and breeding partners," Godden writes at the Conversation.
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