Washington: Researchers have suggested that genetic adaptations for life at high elevations found in residents of the Tibetan plateau likely originated around 30,000 years ago in peoples related to contemporary Sherpa.
These genes were passed on to more recent migrants from lower elevations via population mixing, and then amplified by natural selection in the modern Tibetan gene pool, according to a new study by scientists from the University of Chicago and Case Western Reserve University.
Anna Di Rienzo, PhD, professor of human genetics at the University of Chicago and corresponding author of the study, said that the Tibetan genome appears to arise from a mixture of two ancestral gene pools.
She said that one migrated early to high altitude and adapted to this environment. The other, which migrated more recently from low altitudes, acquired the advantageous alleles from the resident high-altitude population by interbreeding and forming what we refer to today as Tibetans.
To shed light on the evolutionary origins of these gene variants, Di Rienzo and her team, led by first author Choongwon Jeong , graduate student at the University of Chicago, obtained genome-wide data from 69 Nepalese Sherpa, an ethnic group related to Tibetans.
These were analyzed together with the genomes of 96 unrelated individuals from high-altitude regions of the Tibetan plateau, worldwide genomes from HapMap3 and the Human Genome Diversity Panel, as well as data from Indian, Central Asian and two Siberian populations, through multiple statistical methods and sophisticated software.
The researchers found that, on a genomic level, modern Tibetans appear to descend from populations related to modern Sherpa and Han Chinese.
The study has been published in journal Nature Communications.