Tibetans Are Genetically Adapted to Their Country - So that they can survive its thin air

One of the things that stand out most about Tibet is that the country is located at a very high altitude. The air there is therefore very thin, and visitors find it difficult to breathe. As such, altitude sickness is very common among visitors and tourists. In a paper published in the May 13 issue of the top journal Science, researchers showed that Tibetans are in fact genetically adapted to living in their country. Their bodies are especially equipped to handle the lower oxygen concentrations, and so they experience little to no side effects from the high altitude, LiveScience reports.

In a new investigation, the spot in the human genome that underlies this ability was pinpointed. The work showed that people living in Tibet tend to exhibit a variant of a gene that is in charge of determining the level of hemoglobin in the blood. This is the protein that binds to oxygen, carrying the chemical from the lungs to every cell in the human body. By producing low quantities of the stuff in the blood, the bodies of Tibetans become capable of enduring low atmospheric oxygen concentrations, the team behind the new study says.

“Altitude affects your thinking, your breathing, and your ability to sleep. But high-altitude natives don't have these problems. They're able to live a healthy life, and they do it completely comfortably,” explains Case Western Reserve University (CWRU) expert Cynthia Beall. She is also the coauthor of the study detailing the findings, which is published in the latest issue of the esteemed journal Proceedings of the National Academy of Sciences (PNAS). Tibetans tend to live at altitudes as high as 10,000 feet (about 3,050 meters), and sometimes even more.

People that only go to high altitudes occasionally respond to the lower oxygen concentrations by producing more hemoglobin. However, this is not always a good thing, as so many proteins of this type could represent an indicator of a condition characterized by thick and viscous blood. Called chronic mountain sickness, the disease can have negative consequences on the body, but Tibetans do not develop it. “Tibetans can live as high as 13,000 feet without the elevated hemoglobin concentrations we see in other people,” Beall explains.

Blood samples from about 200 Tibetan villagers revealed that the gene called EPAS1 was most likely responsible for this trait. “This is the first human gene locus for which there is hard evidence for genetic selection in Tibetans,” explains Oxford University expert Peter Robbins, also a coauthor of the PNAS paper. “Many patients, young and old, are affected by low oxygen levels in their blood – perhaps from lung disease, or heart problems. Some cope much better than others. Studies like this are the start in helping us to understand why, and to develop new treatments,” concludes Hugh Montgomery, a professor at the University College London, in the UK, and a study coauthor.

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