Tibetans have evolved to live on 40% less oxygen than can be found at sea level. Studies have found that there is a mutated gene called EPAS1 that has been found in 87% of Tibetans, which allows them to function normally at high altitudes without their bodies having to produce more hemoglobin. This may represent the strongest instance of documented evolution in humans to date.
"By identifying genes with mutations that are very common in Tibetans, but very rare in lowland populations we can identify genes that have been under natural selection in the Tibetan population," said Professor Rasmus Nielsen of the University of California Berkeley. "It is the fastest change in the frequency of a mutation described in humans," he said.
Populations living at high altitudes usually adapt by producing more red blood cells that transport oxygen to the body’s tissues, but Tibetans don’t have a high red blood cell count. EPAS1 regulates aerobic and anaerobic metabolism in the body. It helps the body balance anaerobic versus aerobic metabolism in such a way that it is more optimal for the environment of the Tibetan plateau.
What makes this evolution remarkable is that it happened within the last 2,750 years, which, as far as evolution goes, is a really short time frame.
