China’s southwestern mountainous region is home to one of the most ethnically diverse populations in the country. In the most comprehensive genetic analysis of native people to date, researchers reveal that the settlement and migration history of ethnic groups is more complex than previously thought. The study appears on April 26 in the journal Cell reports.
The Tibetan-Yi Corridor (TYC), named after two major ethnic groups in the region, east of the Tibetan Plateau in southwest China, is believed to have served as an important area for migration and ethnic diversification. The corridor’s undulating landscape, composed of deep river valleys and high ridges, formed natural passageways and barriers for gene flow.
Scientists have already analyzed how the region’s inhabitants are genetically related to Tibetans, who live mainly in the west of the region, and the Han, China’s main ethnic group. But previous studies had limited gene samples from the region, which inhabits more than a dozen different ethnic groups.
To gain a better understanding of ethnic groups in the TYC, Shengbin Li, co-corresponding author of the paper at Xi’an Jiaotong University in central China, spent a decade collecting blood samples from over of 200 people from the 16 ethnic groups in the region. .
“The steep mountains that contributed to the high levels of ethnic diversity in the area also made data collection extremely difficult,” Li says. “Most places were inaccessible by car, so we had to travel on horseback. And some groups were so isolated that we had to walk for hours to get there.”
The team selected individuals from each ethnic group with at least three generations of history living in a relatively fixed area. By comparing the genomes of different ethnic groups and those of the Han and Tibetan populations, the team found that all ethnic groups in the region are genetically similar, suggesting that they share a common ancestor. But people living in northern TYC are more closely related to mountain Tibetans living on the plateau, while people in southern TYC have a closer genetic relationship with Southeast Asians, such as Thais and Cambodians. .
Previous research suggests that the region’s first settlers came from the upper reaches of the Yellow River region in northern China during the Neolithic period, and the corridor was gradually populated as settlers expanded towards South. The new study, while not contradicting the previous finding, found that the migration pattern is more complex than just north-south movement. For example, new data suggests that the ancestors of some southern TYC populations may have originated in Southeast Asia.
“More studies are needed to better understand the region’s origin and population flow, especially a more comprehensive analysis that incorporates not only genetic but also archaeological, cultural, linguistic and geographic evidence,” Shuaicheng said. Li, co-corresponding author of the study at Hong Kong Municipal University.
Next, the team hopes to study the gut microbiota of people with TYC. “The region has no air pollution and locals don’t eat processed foods containing chemicals. Their microbiota has the potential to reveal more links between the gut and health,” says Shuaicheng Li.
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