Ainu, Japanese, their ancestors and neighbours: Cranioscopic data.

Seven sutural and two foraminal non-metric characters were studied in ancient and recent skulls from Japan and surrounding areas. Variation of three principal traits in most groups can be best explained by a mixture of two components, Jomon and Mongoloid, the latter one increasing in the following order: West Jomon people -East Jomon people -Hokkaido Ainu -Sakhalin Ainu -Ryukyuans -Yayoi people -Kofun people -West Japanese -Tokyo Japanese . In the Japanese and their ancestors beginning from the Yayoi period, the Mongoloid component is very similar to the one represented in modern Chinese. Its introduction to Japan in Yayoi times was abrupt and obviously caused by massive immigration.