Who are the Japanese? Huge DNA discovery rewrites history

A groundbreaking genetic study conducted by researchers at RIKEN’s Center for Integrative Medical Sciences has revealed a previously unrecognized third ancestral group in the Japanese population, challenging the long-held “dual origins” theory. The study, which analyzed whole-genome sequences from over 3,200 individuals across Japan, identified this third lineage as likely connected to the ancient Emishi people of northeastern Japan. This discovery supports the emerging "tripartite origins" model, suggesting that Japan’s genetic history is more complex and regionally diverse than previously understood. The research involved comprehensive whole-genome sequencing, a method that reads nearly all three billion DNA base pairs, providing vastly more detailed genetic data than earlier microarray techniques. Samples were collected from seven regions spanning from Hokkaido in the north to Okinawa in the south, making it one of the largest genome studies conducted on a non-European population. By integrating genetic data with medical and family histories, the team created the Japanese Encyclopedia of Whole-Genome/Exome Sequencing Library (JEWEL), enabling a nuanced analysis of rare genetic variants that shed light on ancient migration patterns within Japan. Findings revealed significant regional genetic differences, with Jomon ancestry strongest in Okinawa and the newly identified Emishi-related ancestry prominent in northeastern areas. The study also highlighted that the Japanese population is less genetically homogenous than previously assumed, exhibiting distinct subpopulation structures aligned with geographical locations. Additionally, inherited Neanderthal and Denisovan DNA segments were detected, some of which are linked to modern health conditions such as diabetes, heart disease, and cancer, underscoring the ongoing influence of ancient hominin interbreeding on contemporary health. This research not only reshapes the understanding of Japan’s population history but also provides valuable insights into the genetic diversity and health predispositions of its people. The identification of a third ancestral group enriches the narrative of human migration and settlement in East Asia, while the detailed genomic data offers a foundation for future medical and anthropological studies.