Scientists have discovered genes that helped indigenous peoples of Siberia to adapt to life in a cold climate with a restricted diet. Mutations were found in genes affecting lipid metabolism, which involves splitting, digesting, absorbing, transporting, and accumulating fat in the body.
According to the Science in Siberia magazine, the discovery was made by examining DNA samples of Nganasans and Yakut. Afterward researchers confirmed the results on the material of representatives of 17 other ethnic groups in Siberia.
“The study explains the fact that indigenous ethnic groups have a deficient level of low-density lipoprotein, that is, bad cholesterol,” says Lyudmila Osipova, a leading researcher at the Institute of Cytology and Genetics, Siberian Branch of the Russian Academy of Sciences. “All of this despite eating mainly fatty meat food: the usual menu — deer blood, raw meat, fish, raw kidneys, brains.”
The found genes are also involved in the work of brown adipose tissue, which at the molecular level may be responsible for the low level of bad lipids in the blood. Brown fat is activated when it is cold and begins to release energy to warm an organism intensively. It requires fatty acids and glucose, which serve as a kind of “fuel.”
People with active brown adipose tissue have lower total and bad cholesterol levels but higher levels of good cholesterol (high-density lipoprotein). If the cold lasts long enough, brown fat may require fuel all the time, that is, continuously burning many lipids.
Moreover, Siberian natives have accelerated metabolism and elevated levels of thyroxine, a thyroid hormone. Researchers believe that this may also be associated with the genes found through the functioning mechanisms of brown fat: thyroxin activates brown adipose tissue, and an increased release of energy in it requires enhanced nutrition, which can lead to rapid metabolism.
This adaptation mechanism becomes a risk factor when indigenous people switch to a lifestyle with a different type of food, including many carbohydrates. As a result, a shift in metabolism occurs, and overweight appears, resulting in diabetes mellitus of the second type and hypertension. Scientists hope that further research will help find a solution to this problem.
Photo credit: Kirill Kanin / Tayga.info.