Tooth size in Chinese Oroqen ethnic minority of Inner Mongolia Autonomous Region.

The Oroqen are Tungusic hunters of the Amur River basin. We analyzed dental crown measurements from their dental impression models for anthropological characteristics. Sex difference was comparatively larger in the mesiodistal diameters. To examine the Mongoloids' distribution in the Northeast Asia, the data were compared with the results from the previous studies on other Northeast Asian races, using deviation diagrams, cluster analysis, and Multidimensional Scaling from Q-mode correlation coefficients. The Oroqen dentition is classified as Sinodont by the large surface area of their crowns. In the deviation diagram, the Oroqen beared an inverse proportion to the Aleutian Islanders, while showing little difference from the Okhotsk culture people, which suggested a close relation between the two races. The Q-mode correlation coefficients clustered the Oroqen into the Central Asian group with the Buriats and Mongolians. In the analysis of the distances transformed from Q-mode correlation coefficients, the Oroqen was delineated in the neighboring cluster to the Epi-Jomon/Satsumon and the Okhotsk people. It is inferred that the Central Asian group, spreading from Lake Baikal to the Amur basin have gradually mixed with the Baikal group, which later moved into the Amur region from the south. The mixing of the two groups could have been influenced by the geographical features of this area. It would be valuable to gather more data on the groups around the lower Amur region and to evaluate the distribution of the Mongoloids in Eastern Asia.