Geographical Variation of Dental Measurements in the Jomon Population

Abstract

Mesiodistal and buccolingual crown measurements were taken from the permanent tooth remains of the five Middle to Latest Jomon population samples from the Hokkaido, Tohoku, Kanto, Tokai and San'yo districts of Japan. The metrical data were compared with each other through multivariate statistical methods. The analysis of variance for these crown measurements suggested that most of the variables showing significant geographical difference were buccolingual diameters. The distance analysis based on the crown measurements revealed that the Hokkaido Jomon was isolated from the Jomon in Honshu, the main island of Japan. The Honshu Jomon groups were closely related to each other, although the male Tohoku Jomon was slightly closer to the Hokkaido Jomon. The principal factor analysis revealed that the overall dental proportion of the Hokkaido Jomon was different from those of the Honshu Jomon groups, and the Tohoku Jomon carried the smallest overall tooth size among the five Jomon population samples compared. From the comparisons with recent groups, it was indicated that 1)the diversity in dental morphology between the Hokkaido and Honshu Jomon was smaller than that between the recent Kanto Japanese and the Jomon as a whole; 2) the dentition of the Jomon population was characterized by relatively small canines, premolars and second molars as compared with thefirst molars; 3) these dental characteristics could also be seen in the dentition of the Ainu. These facts suggested a close affinity between the Ainu andJomon in the posterior tooth characteristics. However, with regard to the anterior teeth, both the relative and absolute dimensions of the incisors werelarger in the Jomon than in the Ainu. Thus, the size reduction of the incisors may have proceeded from the prehistoric Jomon to the recent Ainu.