While America is about to fight North Korea, and both are waving nuclear clubs, scientists wondered if humanity can survive if it comes to war. It turned out - yes. But not all.
The nuclear winter test can be overcome by those people whom nature has awarded with the so-called cold gene, according to scientists from the University of Arizona and employees of the Institute of Cytology and Genetics of Novosibirsk, who together studied genetic signs of adaptation to cold in the indigenous peoples of Siberia.
The latter have genetically adapted to survive in one of the coldest and most stressful places on the planet. Despite the limited daylight hours, food items and severe cold, modern people settled in Siberia about 45 thousand years ago - after the initial migration from Africa.
Who is older - Yakut or Nganasan?
Scientists in field expeditions collected 21 samples of DNA from the peoples of two Siberian populations - the Nganasan (nomadic hunters of Taimyr) and the Yakut (reindeer herders), in which exomes (protein-coding genes) were isolated and sequenced (determining the order of DNA blocks (nucleotides) in the human genetic code). The method allows for mass screening of genes and detection of mutations in protein-coding sequences.
The results were connected with data from several sequencing of the East Asian and European populations of the "Genome 1000" project. A total of 508160 single nucleotide variants (SNVs) or DNA mutations were obtained, considering which, scientists looked for "genetic signatures" (markers) common for adaptation of populations to cold.
“Our conclusion suggests that the common ancestors of the Nganasans and Yakuts separated from their East Asian ancestors about 12-13 thousand years ago, maintaining trade with them,” the report says. Its authors suggest that this may have coincided with the end of the last glacial maximum and the beginning of warming in the Holocene, which allowed people to migrate to the north of Central Siberia.
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The data obtained indicate that the two named Siberian populations lived in isolation from each other and were subjected to serious tests under the influence of the environment.
Three groups of genes associated with nutrition
Researchers have found evidence of a dramatic - almost 90% - population decline in the ancestors of East Asians and Siberians. Subsequently, the populations recovered and expanded to their current levels.
“Our study identified seven genetic signatures with specific signals from Siberia,” says Professor Ryan Gutenkunst. "Three types of markers are associated with nutrition, especially fat metabolism, in accordance with the hypothesis of adaptation to a diet rich in animal fat."
“All of them play an important role in energy production and the structure of cell membranes, digestive enzymes, digestion and absorption of proteins,” explains the researcher.
According to the scientist, many Siberian indigenous peoples, including the Nganasans and Yakuts, have now fully adapted to a diet rich in fats and proteins. However, physiological studies have shown that they have significantly higher metabolic levels and relatively low levels of lipids (a group of naturally occurring organic compounds that include fats and fat-like substances) in the blood (eg HDL / LDL and triglycerides).
In other words, by consuming fatty foods, the indigenous peoples of the North do not gain weight due to their high metabolism.
“This genetic adaptation involves the body's defenses to maintain stable plasma lipid levels to cope with severe cold stress,” the report said.
The new study is consistent with similar results among other cold-adapted populations, including the Greenland Inuit in the Arctic.
LYUBOV STEPUSHOVA