Home History Three-Part Origin of the Japanese People

Three-Part Origin of the Japanese People

Daisen-Kofun, the tomb of Emperor Nintoku, Osaka Photo © National Land Image Information

By David Yamaguchi The North American Post

In September 2021, an article appeared in the scientific journal, “Science Advances,” that scarcely garnered media coverage, but should have. It presents genetic evidence that the origins of present-day Japanese people derive from three sources, not two as previously thought. This matters because many people today want to know where their ancestors came from and something of their journey across space and time. 

“Genetic diversity through time in Japan.” At upper left, Jomon Period (14,000 – 300 BC) skeletons reveal a “pure Japanese” genetic composition (red). This becomes diluted by one-fourth during the Yayoi Period (300 BC to 300 AD) and again to 80 percent during the Kofun Period (AD 250-538). The latter change in genetic composition is the largest, and results in one similar to that of modern Japanese (upper right). The second and third rows provide a menu of ancient populations from which the Yayoi and Kofun people may have come. The second row is essentially China; both the Yellow River and Liao River empty into the Yellow Sea east of Beijing. The third row is present-day Russia (left) and Kazakhstan (right). Image from NP Cook and others, 2021, Ancient genomics reveals tripartite origins of Japanese populations, Science Advances, v. 7, no. 38 (17 Sep.).

Regular readers of this paper will remember that the Japanese have been thought of as the descendants of two peoples. The Jomon were the original indigenous people of Japan. The Ainu descend from these original hunter-gatherers. The Jomon were later joined by the Yayoi, rice farmers from Korea, who spread northward across the archipelago.

This conventional view of Japanese anthropology was recently upended by genetic studies of ancient East Asian skeletons. It turns out that a third group joined the original two, in large enough numbers to nearly dwarf their genetic contributions to present-day Japanese.

The third group is now believed to be the kofun builders, who were apparently distinct from the Yayoi rice farmers. Recall that kofun are the commonly enormous burial tombs built for Japanese rulers. Over 161,000 of them were made across Japan during the third to sixth centuries. 

Rivers and regions mentioned in the top figure and text, north to south.

What does the genetic evidence for the new interpretation of the Japanese past look like? They are summarized as color-coded diagrams in the original research paper, reproduced above. What is most surprising is that it is the arrival of the kofun builders, not the Yayoi farmers, that most substantively changed Japanese population genetics. This change may be the result of the arrival of many more kofun builders than Yayoi farmers. Alternatively, the latter may have died off owing to their increased exposure to continental diseases, or to their being killed by superior weapon technology, as happened in the Americas.

The remaining question is, where did the kofun builders come from? The short answer is “southern and eastern China,” for the ancient people of the Russian Far East and Central Asia were too different genetically from present-day Japanese. Interestingly, the Yayoi people appear to descend from these regions, especially the Amur River (green band). 

The bottom line is that present-day Japanese people are more ethnically Chinese than we have known. 

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David Yamaguchi is a third-generation Japanese American [Sansei]. He has written for the Post since 2006, at first as a volunteer, later as a paid freelancer. He joined the paper's staff in May 2020, when he began learning how articles flow from Word files through layout to social media.