A comparative study of nonmetric cranial variation revealed population affinities between the Northeast and East Asians. The recent eastern Siberian populations were basically divided into the three groups defined by Debets (1951), though the Baikal group peoples, consisting of the Amur, Evenki and Yukagir, do not cluster together. The Yukagir remain intermediate between the Baikal and Central Asian groups, while the Evenki are isolated from other Siberians, probably because of their small sample size. The Neolithic Baikalian are close to the Amur peoples, while the Troitskoe of the Mo-ho culture from the Amur basin show some close affinities with the Central Asian group. Because the Central Asian group peoples are more similar to the Northern Chinese than to the Neolithic Baikalian, the former two seem likely to have interacted with each other since the Neolithic age. The Hokkaido Ainu show no close affinity with the Neolithic or the later Siberian Mongoloids, nor with the Europeans.
The Anthropological Society of Nippon