Cold Tolerance Among Inuit May Come From Extinct Human Relatives

Dec 30, 2016

By Steph Yin

Inuit who live in Greenland experience average temperatures below freezing for at least half of the year. For those who live in the north, subzero temperatures are normal during the coldest months.

Given these frigid conditions, anthropologists have wondered for decades whether the Inuit in Greenland and other parts of the Arctic have unique biological adaptations that help them tolerate the extreme cold.

A new study, published on Wednesday in Molecular Biology and Evolution, identifies gene variants in Inuit who live in Greenland, which may help them adapt to the cold by promoting heat-generating body fat. These variants possibly originated in the Denisovans, a group of archaic humans who, along with Neanderthals, diverged from modern humans about half a million years ago.

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One comment on “Cold Tolerance Among Inuit May Come From Extinct Human Relatives”

  • @OP – Strikingly, all of the Inuit studied contained the same genetic variants in this particular region of their genomes. Compared to the same region in Neanderthals and other modern populations, the Inuit region showed at most a partial match. But compared to the Denisovan genome, it “was almost a complete match,” Dr. Nielsen said.

    Over all, the fact that the variants are present in close to 100 percent of Greenlandic Inuit could imply that they carry some type of evolutionary advantage.

    “We do see these variants in other populations, like in South America and East Asia, but nowhere do we see the same frequency that we see in Greenland,” Dr. Nielsen said. “That suggests that natural selection occurred there.”

    Interestingly, genes from the Denisovian genome have also been linked to adaptation to high altitude environments, so that could be the reason for the incidences in Andes and perhaps the Himalayas.

    Cold would also be an issue in these environments, but perhaps selection was more intense or different in the Arctic.

    A “superathlete” gene that helps Sherpas and other Tibetans breathe easy at high altitudes was inherited from an ancient species of human. That’s the conclusion of a new study, which finds that the gene variant came from people known as Denisovans, who went extinct soon after they mated with the ancestors of Europeans and Asians about 40,000 years ago. This is the first time a version of a gene acquired from interbreeding with another type of human has been shown to help modern humans adapt to their environment.

    Researchers have long wondered how Tibetans live and work at altitudes above 4000 meters, where the limited supply of oxygen makes most people sick. Other high-altitude people, such as Andean highlanders, have adapted to such thin air by adding more oxygen-carrying hemoglobin to their blood. But Tibetans have adapted by having less hemoglobin in their blood; scientists think this trait helps them avoid serious problems, such as clots and strokes caused when the blood thickens with more hemoglobin-laden red blood cells.

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