China: A new genetics study has revealed that some of the first humans to migrate to the Americas included individuals from China. Previous studies had suggested that Native Americans were descended from ancient Siberians who had crossed over a land bridge between Russia and Alaska. However, more recent research suggested that the ancestry of the founding populations of the Americas might have more diverse sources from Asia, including in Bolivia, Brazil, Chile, Ecuador, Mexico, and California. The lineage responsible for these populations, known as D4h, is found in mitochondrial DNA inherited only from mothers.
Researchers from the Kunming Institute of Zoology conducted a decade-long search for D4h, combing through 100,000 modern and 15,000 ancient DNA samples from across Eurasia, eventually identifying 216 contemporary and 39 ancient individuals who came from the ancient lineage. By analyzing the mutations that had accrued over time and the geographic locations of the samples, the team was able to reconstruct the lineage’s origins and expansion history.
“Our findings indicate that besides the previously indicated ancestral sources of Native Americans in Siberia, the northern coastal China also served as a genetic reservoir contributing to the gene pool,” Mr. Yu-Chun Li, one of the report authors, commented.
“However, we don’t know in which specific place in northern coastal China this expansion occurred and what specific events promoted these migrations. More evidence, especially ancient genomes, are needed to answer these questions,” Mr. Li added.
The results showed two migration events. The first occurred between 19,500 and 26,000 years ago during the Last Glacial Maximum, when the ice sheet coverage was greatest and climate conditions in northern China were likely inhospitable. The second occurred during the melting period between 19,000 and 11,500 years ago, when increasing human populations might have triggered migrations. This finding aligns with archeological similarities between ancient people in the Americas, China, and Japan. The study further provides new insights into the complex genetic history of the Americas and the origins of its earliest inhabitants.