The research, published in the Proceedings of the National Academy of Sciences, offers valuable insights into human evolution and adaptation to extreme environments.
Researchers collected data on reproductive histories, physiological measurements, and DNA samples to understand how oxygen delivery traits influence reproductive success in high-altitude conditions.
Key Findings
Women living at high altitudes (≥2,500 m) can encounter additional stress during pregnancy. High-altitude pregnancy increases the risk of preeclampsia or low birthweight which raises the risk of maternal or infant death. When comparing the pregnancy-related biology of Tibetan women with that of migrants to high altitudes, Tibetan women have lower hemoglobin concentration, higher oxygen saturation of hemoglobin and uterine artery blood flow, and heavier newborns. Among Tibetan women who have completed childbearing, unelevated hemoglobin concentration, higher oxygen saturation, and a higher pulse rate correlate with higher lifetime reproductive success. This pattern of human variation suggests the action of natural selection on oxygen delivery phenotypes.