How migrations and diet contributed to the formation of ancient Japan's population

New DNA analysis of ancient individuals in Japan is shedding light on the complex migratory patterns from East Asia and the early dietary adaptations of its inhabitants. The study provides some of the most detailed genetic data to date from people who lived in ancient Japan, tracing how migrations, climate shifts, and diet shaped the archipelago's population.

The research focused on the genomes of two individuals separated by thousands of years: a woman from the early Jōmon period, living approximately 8,300 years ago, and a man from the Yayoi period, who lived about 2,300 years ago. Obtaining high-quality genomes from ancient Japan is challenging due to DNA degradation in warm, humid conditions and acidic soils. However, researchers achieved unusually high genomic coverage for both samples, enabling precise comparisons of their genetic origins.

The analysis revealed significant genetic differences between the two individuals. The Jōmon woman belonged to a population genetically close to earlier groups associated with the Jōmon culture, providing new evidence of a Jōmon genetic lineage contributing to modern Japanese ancestry. In contrast, the Yayoi man showed closer genetic ties to populations currently inhabiting Japan's main islands, with additional genetic components linked to Northeast Asian populations.

Further analyses of Yayoi period populations indicated connections to various ancient continental Asian groups, including those from the Amur River region, Inner Mongolia, and Shandong. Notably, the study identified genetic clues suggesting that adaptations for digesting starch were present in the region before rice agriculture became widespread. This research was led by Koji Ishii from Kanazawa University.