High-altitude adaptation in humans

High-altitude adaptation in humans is an instance of evolutionary modification in certain human populations, including those of Tibet in Asia, the Andes of the Americas, and Ethiopia in Africa, who have acquired the ability to survive at extremely high altitudes. This adaptation means irreversible, long-term physiological responses to high-altitude environments, associated with heritable behavioural and genetic changes.

While the rest of the human population would suffer serious health consequences, the indigenous inhabitants of these regions thrive well in the highest parts of the world. These people have undergone extensive physiological and genetic changes, particularly in the regulatory systems of oxygen respiration and blood circulation, when compared to the general lowland population.

This special adaptation is now recognised as an example of natural selection in action. The adaptation account of the Tibetans has become the fastest case of human evolution in the scientific record, as it is estimated to have occurred in less than 3,000 years.

Humans evolved in Africa and dispersed from it less than 100,000 years ago, eventually colonising the rest of the world, including the harshest environments of extreme cold and high mountains. The abundance of oxygen in the atmosphere is inversely related to altitude from the sea level; hence, the highest mountain ranges of the world are considered unsuitable for human habitation.

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