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Researchers have found that genetic adaptations for life at high altitude found in Tibetan people originated around 30,000 years ago. Genes were then passed on to more recent migrants from lower elevations making them perform better at high-altitude. 

The study performed by scientists at the University of Chicago and Case Western Reserve University found that the transfer of beneficial mutations between human populations and selective enrichment of the genes in subsequent generations presented a unique mechanism that is capable of adapting to new environment. 

"The Tibetan genome appears to arise from a mixture of two ancestral gene pools," said Anna Di Rienzo, PhD, professor of human genetics at the University of Chicago and corresponding author of the study, in the press release. "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."

On a genomic level, researchers noted that modern Tibetans appeared to be related from populations of Sherpa and Han Chinese. They also said Tibetans carried a mixture of two ancestral genomes. One of the two genomes helped in adapting high-altitude environment, while the other low-altitude environment like lowlander East Asians. 

"This is a good example of evolution as a tinkerer," said Cynthia Beall, PhD, professor of anthropology at Case Western Reserve University and co-author on the study, in the press release. "We see other examples of admixtures. Outside of Africa, most of us have Neanderthal genes-about 2 to 5 percent of our genome-and people today have some immune system genes from another ancient group called the Denisovans."

The analysis also revealed that the adaptations were unevenly enhanced in frequency in Tibetans. 

"There is a strong possibility that these genes are adaptations to high altitude," Di Rienzo added in the press release. "They represent an example of how the ancestry-based approach used in this study will help make new discoveries about genetic adaptations."

The study is published in the Nature Communication.