A new study by the indigenous peoples of Siberia showed how natural selection helped to adapt to the northern cold. It was also found that different populations did it my way.
|A gentleman with a tube of Buryatia (photo Alexander Newby).|
Siberia occupies about 10% of the Earth's land, but it is considered his home only about 0.5% of the world population. This is not surprising: the average January temperature is -25 ° C. Genetics still covered a handful of local people. Meanwhile, some of them are on the verge of extinction, for example, were once numerous Teleuts ranchers, and now there are only two thousand people.
Previous research on the adaptation to cold, included only two Siberian populations and found a couple of the corresponding genes. According to a paper published in 2010 by Anna Di Rienzo University of Chicago (USA), UCP1 and UCP3 found in more active forms of the people living in cold climates. These genes help the body's fat stores to produce heat directly – instead quiver production of chemical energy for muscles and the brain (non-shivering thermogenesis).
In the new sample, Siberians are more widely – as many as ten groups, almost all of the native population. Alexis Cardona, University of Cambridge (UK), and her colleagues analyzed 200 samples of DNA from the collection of the Institute of Biological Problems of the North FEB RAS. Using techniques to detect signs of natural selection in the human genome (ie genes, caressed evolution for what they have helped to survive and reproduce), found three genes that survived positive selection: UCP1, ENPP7 and PRKG1.
PRKG1 involved in smooth muscle contraction, resulting in tremors and narrowing of the blood vessels in order to prevent heat loss. A ENPP7 involved in the digestion of fats, especially those that are in meat and dairy products, the underlying diet of the Far North.
"Cold-loving" versions of these genes are present in different people in different degrees. Thus, residents of southern Siberia prefer UCP1, and the North-East and Central – PRKG1. ENPP7 distributed throughout Siberia.
At the same time the findings are proof of the theory of natural selection: you can see how apparent selection pressure is adapted differently for different groups of 25 thousand years for the cold and the meat diet.
Ms. Cardona recalled that in Siberians and American Indians – the same ancestors, so the first American settlers caught in the New World during the Ice Age, to adapt to the cold weather the same way. In addition, in Siberia and Neanderthals lived with mysterious denisovtsami: it would be interesting to know how they managed to do the same.
The results were presented at the Conference on the origin of man.
Prepared according to ScienceNOW.