Mitochondrial DNA analysis of the human skeletons excavated from the Shomyoji shell midden site, Kanagawa, Japan

Recent studies have revealed that the Jomon people are considerably genetically different from any other population, including modern-day Japanese. This gives rise to an intriguing question: when after the Jomon era did this drastic change of genetic features occur? The Shomyoji shell midden site in Kanagawa, Japan can provide some clues to address this question. The skeletons buried at this site include some that are more recent than the Jomon-era skeletons with whom they are almost contiguously buried. We tested the genetic continuity of the Shomyoji shell midden people by analyzing mitochondrial DNA (mtDNA). Our results show that the mtDNA haplogroups of the Kofun and Heian skeletons vastly differ from those of the Jomon skeletons. This finding implies that the genetic conversion of the Japanese people may have occurred during or before the Kofun era, at least at the Shomyoji site. To confirm this hypothesis, nuclear genome analysis of the Shomyoji people is considered promising.