A team led by scientists at the University of Oklahoma used next-generation sequencing to study eight ancient DNA samples from the Himalayas, enabling them to determine a “strong and consistent genetic affiliation” to contemporary East Asians — Tibetans and Sherpas.
The samples came from eight individuals who lived 3,150—1,250 years ago and whose relics were found in the Annapurna Conservation Area, Nepal.
The results, detailed in a paper published last month (July) in PNAS, should dispel theories of other origins for Himalayan populations, in South Asia, Central Asia, West Eurasia and Southeast Asia, as well as speculation about prehistoric population replacement of the mix with lowland populations, according to the authors.
Christina Warinner, assistant professor of anthropology at the University of Oklahoma, and corresponding author of the paper, said she was “surprised” by how genetically stable the population in the Himalayan Arc was. Warinner notes that while the material culture of the Himalayas shared many features with the lowland cultures on the Ganges Plain, hinting at common ancestry, the genomes of the ancient samples interrogated showed no sign of such admixture.
“Elsewhere in the world, such as in prehistoric Europe, changes in material culture and genetics almost always go hand in hand,” says Warriner. “By contrast, in the Himalayas new ideas, goods, and religious beliefs were adopted by these high-altitude peoples without population change.”
The authors speculate that topographical differences may have made it easier for East Asian populations to move into the Himalayan Arc, than South Asians, given that the altitudinal gradient is more gradual in the north than it is in the south of the arc, allowing migrants from the Tibetan Plateau to stay at intermediate altitudes and acclimatise.
Based on the genetic data, scientists were able to determine that EGLN1, a marker found in Tibetan populations associated with adaptation to high altitudes, was already present in the earliest samples sequenced. The marker EPAS1 was found only in more recent samples, meaning that it perhaps played a less important role in high-altitude colonisation than previously thought.
“We had assumed that [the markers] would appear together, but it is clear that selection for EGLN1 predates EPAS1,” Warinner says. “What this means we don't yet know, but it certainly changes our understanding of high-altitude adaptation in the region.”
Chuanchao Wang, a geneticist at Harvard Medical School, called the team’s findings “super exciting,” noting that it contains the first genome-wide sequencing data for ancient individuals in the region.
According to Wang, the study has helped to “solve the long-standing dispute on the origin of the earliest Himalayan inhabitants that they were from East Asia rather than from West Eurasia, South Asia, Central Asia, or lowland Southeast Asia.”
This piece was produced by SciDev.Net’s South Asia desk.