Scientific American reports
that the residents of Tibet are able to handle the low levels of oxygen found when living at an average altitude of almost 15,000 because their bodies are, quite simply, different than anywhere else in the world.
Tibetans have bigger arteries and higher blood flow than the rest of us. The cells lining their blood vessels produce nitric oxide, which turns into nitrite and nitrate in their blood, making them expand and the amount of blood flowing through them to increase quite a bit.
And get this: Tibetans have higher levels of nitrite and nitrate than people with septic shock
, which is a dangerous blood infection. They breathe more than anyone else, and have more antioxidants in their blood than the rest of us as well. Oh, and the article notes as merely an aside that residents of the Andes in South America don't have these characteristics; they just have larger lungs than the rest of the human race.
The human ability to adapt and thrive in any setting is truly remarkable. It's all the more so because this adaptability comes not only through our intelligence and tool-making abilities, but also because we have such incredibly mutable genes, producing extremes in skin color, height, bone structure and even the chemical processes our bodies use to get needed oxygen from the air.