Tibetan People - Physical Characteristics

Physical Characteristics

Tibetans are phenotypically diverse. Recent research into the ability of Tibetans' metabolism to function normally in the oxygen-deficient atmosphere above 4,400 metres (14,400 ft) shows that, although Tibetans living at high altitudes have no more oxygen in their blood than other people, they have 10 times more nitric oxide and double the forearm blood flow of low-altitude dwellers. Nitric oxide causes dilation of blood vessels allowing blood to flow more freely to the extremities and aids the release of oxygen to tissues. It is not known whether the high levels of nitric oxide are due to a genetic mutation or whether people from lower altitudes would gradually adapt similarly after living for prolonged periods at high altitudes.