Ancient DNA Signals Reveal Overlooked “Third Ancestral Group” in Japanese History, Rewriting Dual-Origin Model

A landmark May 2026 Science Advances study by RIKEN researchers has uncovered compelling evidence for a previously unrecognized third ancestral population in the genetic makeup of modern Japanese people. Whole-genome sequencing of more than 3,200 individuals across the Japanese archipelago reveals a distinct northeastern Asian component that challenges the long-standing “dual origins” theory of Jomon hunter-gatherers plus later East Asian rice farmers.

The new lineage, most prominent in northeastern Japan, is genetically linked to ancient populations from the broader northeastern Asian mainland and may correspond to the historical Emishi people of northern Honshu. This triparтιтe model—Jomon, East Asian, and this third northeastern Asian source—had been hinted at in 2021 ancient DNA studies but lacked the statistical power of the current mᴀssive modern dataset.

Lead author Chikashi Terao noted: “Our data show that Japanese ancestry cannot be explained by just two sources. The third component is real, geographically patterned, and leaves detectable traces in health-related variants today.”

The discovery also detects lingering Neanderthal and Denisovan DNA, with regional variation suggesting multiple pulses of archaic admixture. By integrating modern genomes with ancient reference panels, the team demonstrates how overlooked ghost lineages can be recovered without new fossil finds.

This finding transforms our understanding of East Asian prehistory: migration and mixing were far more layered than textbooks described. The “third ancestral group” proves that human history in the Japanese archipelago was shaped by at least three major waves, adding a new chapter to the complex story of our species.