It is not easy to breathe on the roof of the world. A few days ago, Kilian Jornet told in the revolt that, while he went down from Everest, He began to suffer hallucinations And convinced that he was dreaming he was about to jump into the void. And it makes sense because, thousands of meters above sea level, there is simply less oxygen in each breath of air. It is, we could say, pure physics.
However, for more than 10,000 years, Tibetans have not only survived these dementeial conditions of that environment: they have prospered.
But how? It is a question that has intrigued anthropologists for years. And if we think a little, he has his crumb. For decades, it has been said that evolution is slow and that, in general terms, human beings are more or less the same as we were in the Paleolithic. How could it be that Tibetans (who would not cease to be people like us) have prospered all this time If that is so?
The answer is very simple: not being. A few months ago, anthropologist Cynthia Beall, from Case Western Reserve University, published PNAS investigation which clarifies all this and reveals “how the physiological features of Tibetan women improve their ability to reproduce in an environment with such a shortage of oxygen.”
It is live and live evolution.
What did they do? Beall and his team They studied 417 Tibetan women between 46 and 86 years old who lived around 4,000 meters above sea level in Alto Mustang, Nepal; that is, at the southern end of the Tibetan plateau.
They collected many data: from their reproductive history to physiological measurements, DNA samples or a wide set of social factors. Its intention was precisely to understand how the characteristics of oxygen supply in high altitude hypoxia conditions influenced the number of living births. Because? Because it is a key measure of the evolutionary aptitude of these women.
And so it was. Because what they discovered is that women who had more living children had a “unique set of blood and cardiac characteristics” that helped their bodies to distribute oxygen. Specifically, They discovered That although these women had middle levels of hemoglobin, it was more saturated.
It was a fantastic solution because it allowed an efficient distribution without increasing the viscosity of the blood (and, therefore, without forcing the heart more than necessary).
What does all this mean? Something really interesting. Because work Not only does it underline “the remarkable resilience of Tibetan women”but they also offer valuable information about the ways in which human beings can adapt to extreme environments.
After all, “it is a case of natural selection in progress. Tibetan women have evolved in a way that balances the oxygen needs of the body without overloading the heart,” Beall explained. And, understanding how populations like these are adapted, “it gives us a better understanding of human evolution processes.”
Something that, on the other hand, we need. Because in the end, it turns out that the unity of the human species is only sustained by the similar environmental conditions in which we move. But what will happen when we become an “interplanetary species”?
And the answer is simple: that We can never go home. The unity of the species will be detrimental to our adaptive success.
Image | Will Pagel
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