Genetics of human origin and evolution: high-altitude adaptations.

High altitude, defined as elevations lying above 2500m sea level, challenges human survival and reproduction. This environment provides a natural experimental design wherein specific populations, Andeans, Ethiopians, and Tibetans, have lived in a chronic hypoxia state for millennia. These human groups have overcome the low ambient oxygen tension of high elevation via unique physiologic and genetic adaptations. Genomic studies have identified several genes that underlie high-altitude adaptive phenotypes, many of which are central components of the Hypoxia Inducible Factor (HIF) pathway. Further study of mechanisms governing the adaptive changes responsible for high-altitude adaptation will contribute to our understanding of the molecular basis of evolutionary change and assist in the functional annotation of the human genome.