Researchers have found that the polar bears have differentiated from brown bears in more recent times than what was believed in the scientific community — there is only 70,000 years — and it was more gradual than anyone imagined.
The polar adaptation to survive hostile climates appeared in genes for fur type and color and cardiovascular functions, allowing the species to live at the poles, as it does today.
By analyzing the genomes of 119 and two fossils of polar bears and 135 brown bears, researchers were able to determine that the differentiation between the species occurred around 70,000 years ago.
The results of research conducted by a team of molecular ecologists from the University of Copenhagen in Denmark were published in BMC Genomics Journal last Monday (16).
It has been discovered that the differences between the two species appear not only in the color of their fur, but also in its structure. Polar bears have two layers of fur — a downy layer to keep them warm and an outer layer to keep them dry.
In addition, the bears’ cardiovascular functions were altered in order to eat meat that was high in fat and cholesterol. If the grizzlies had such a high-fat diet, they would have developed heart disease and died young.
From these findings, researchers hypothesized that polar bear adaptations may have been influenced by animals that lived during the final stages of the last ice age.
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This content was originally published in Polar bears adapting to the cold happened earlier than previously thought, says study on the CNN Brasil website.
Source: CNN Brasil
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