Tibetans developed unique high-altitude adaptations over 10,000 years: study

Tibetan communities have developed remarkable physiological adaptations over the past 10,000 years, enabling them to thrive in the extreme low-oxygen environment of the Tibetan Plateau.

This discovery highlights that human evolution is still ongoing, as our bodies continue to adapt to challenging environments.

At high altitudes, oxygen levels are significantly lower than at sea level, making it difficult for most people to breathe. Many who travel to high-altitude regions suffer from hypoxia, a condition caused by insufficient oxygen supply to the body. However, Tibetans have evolved unique traits that allow them to function normally in these conditions, whereas newcomers often experience altitude sickness.

Generations of Tibetans have developed an enhanced ability to extract and utilise oxygen, enabling them not just to survive but to live healthy and active lives in an environment that would challenge most other humans.

The study, led by Cynthia Beall, a University Professor Emerita at Case Western Reserve University, was published in the Proceedings of the National Academy of Sciences (PNAS) on October 21. It sheds light on how Tibetan women have developed distinct physiological traits that improve their ability to give birth and reproduce in an oxygen-deprived environment.

Comparing Tibetan women with migrants who move to high-altitude areas, researchers found that Tibetans have lower hemoglobin concentrations (which prevents excessive blood thickening), higher oxygen saturation of hemoglobin, increased uterine artery blood flow, and heavier newborns, leading to higher reproductive success.

Among Tibetan women who have completed childbearing, higher oxygen saturation, lower hemoglobin levels, and an increased pulse rate were linked to a greater number of successful pregnancies.

"Adaptation to high-altitude hypoxia is fascinating because the stress is severe, experienced equally by everyone at a given altitude, and quantifiable," said Cynthia Beall in an interview with ScienceAlert. She described these adaptations as a clear demonstration of why humans exhibit so much biological variation.

This study shows that evolution is not a thing of the past. It continues to shape human populations as they adjust to their surroundings. The Tibetan Plateau, which has been continuously inhabited for over 10,000 years, provides a striking example of natural selection at work in modern times.