A recent study suggests human altitude adaptation in Tibet may be linked to the introgression of DNA from human ancestors such as Denisovans.
A recent study, published in Nature, provides new insight into how humans adapt to diverse environments such as extreme temperatures and high altitudes, BGI Shenzhen said. These types of adaptations have allowed Tibetans to live at 13,000 feet all year around without suffering health consequences.
Scientists have long-wondered how Tibetans conquered the threat of hypoxia in this harsh environment. Hypoxia is a lower-than-normal level of oxygen in the blood, Mayo Clinic reported. The potentially-fatal condition is characterized by "severe shortness of breath with headache, insomnia, fluid retention and cough," it can occur at altitudes above 8,000 feet.
Recent studies on the genetics of Tibetans identified a hypoxia pathway gene, EPAS1, whicht may have been linked to differences in hemoglobin concentration at high altitudes. To make their findings the research team re-sequenced the region around EPAS1 in 40 Tibetan and 40 Han individuals. The team found the gene in Tibetans had a slightly different haplotype that has only been observed in certain regions of the Denisovan genome.
In past studies researchers have found evidence for Denisovan admixture throughout Southeast Asia; this means early Tibetans may have bred with the human ancestors. This event may have facilitated the adaptation to higher altitudes.
"The Denisovan-like DNA we found in the genome of Tibetans implied that the adaptation to local environments could be facilitated by gene-flow from other hominins who have been adapted to such environments. This unique finding may help us re-examine the similar fast-evolution cases in the future," in Jin, Research Scientist from BGI, said.
"The genetic relationship or blood relationship between modern human and archaic hominins is a hot topic of the current paleoanthropology. . The finding of Tibetans's selected EPAS1 haplotype in Denisovans not only demonstrates the possibility of ancient gene-flow from Denisovans- or -like population to ancestors of Tibetans , but also shows the importance of such events in local adaptation of modern humans," Asan Ciren, Another researcher from BGI, said.
