How Tibetans adapted to a lack of oxygen in the highlands

Tibet is an amazing country located in the Himalayas at an altitude of 5000 m and above sea level.

Alpine air, in contrast to the flat, which we breathe, has a number of features. In people living at atmospheric pressure of 760 mm. Hg. Art., the saturation of hemoglobin with oxygen is 96%. But as soon as an ordinary person gets into the highlands, this figure begins to fall rapidly. And at an altitude of, for example, 6.5 km, where atmospheric pressure is only 330 mm. Hg. Art., oxygen saturation is only 65%. And at an altitude of more than 8 kilometers, this figure drops to 50%. Naturally, at the same time, negative processes begin to develop in the body of an unprepared person, leading to hypoxia, an increase in blood viscosity, an increase in likely cardiovascular pathologies, and even to high-altitude pulmonary edema.

But there are peoples on our planet that can survive even in such inappropriate conditions. First of all, these are Tibetans and Sherpas close to them, as well as Indians living in the Andes at an altitude of more than 4000 m. All these people are distinguished by excellent health and high life expectancy. But, as scientists recently found out, they came to such excellent results in different ways.

For example, the inhabitants of the Andes have more lung capacity, and they breathe less often than you and I. Moreover, a higher content of red blood cells was found in their blood, which are responsible for the transfer of oxygen, carbon monoxide and nutrients in the body. This explains the fact that chronic mountain sickness is highly prevalent among them, which, however, does not greatly complicate their lives. But the most interesting thing is that when moving to the plain an unpleasant ailment passes. That is, the mechanism of adaptation to the highlands of these peoples is purely physiological in nature and acts on the principle of training.

But the Tibetans went the other way. As a group of Chinese and Australian scientists found out, the DNA of representatives of this people contains special genes EGLN1 and EPAS1, which are responsible for more efficient use of available oxygen, without increasing the number of red blood cells. Later, an additional 7 genes with even more complex names were deciphered. These genes are unique to Tibetans, that is, they are not found in such a combination and in the right amount more than any other nation on our planet. One of them, in particular, helps to slow down the metabolism, which allows Tibetans to maintain normal weight with poor nutrition. A unique set of genes is also responsible for the content of nitric oxide in tissues, which contributes to the expansion of blood vessels. Scientists also note that Tibetans have a much higher respiratory rate than residents of lowland areas.

An equally interesting fact is that the EPAS1 gene is identical to the gene found in the study of DNA from the remains of Denisovans. These ancient people lived in Altai and, perhaps, are those from whom the Tibetans inherited this gene.

Thus, it turns out that the well-being and endurance of the inhabitants of Tibet is not due to the fact of being in the highlands since infancy, but they are inherited genetically and are inherent in all Tibetans from birth.

According to archaeological evidence, the first human settlements in the Tibet region appeared more than 5,000 years ago. It turns out that this people managed for such a short period by evolutionary standards not only to acquire unique mechanisms of adaptation to rarefied air, but also to fix them at the genetic level.