Abstract

The frequencies of occurrence of 17 tooth crown traits in the living Ami tribe, which inhabits the east coast of Taiwan, were investigated and compared with other East Asian populations based on Turner's (1987) Mongoloid dental variation theory. Principal coordinate analysis based on Smith's mean measure of divergence using frequencies of the 17 traits suggests that the Ami tribe together with the Yami tribe and the Bunun tribe is included in the sinodont group typical of the Chinese mainland and northeast Asia. In light of these results and the estimated distribution of sinodonty and sundadonty in the past and the present, we speculate that the gene flow from Chinese mainlanders to native sundadonts, who seem to have migrated northward to Taiwan, contributed significantly to the formation of the living Taiwan aboriginal groups, sinodonts. Among the aboriginal tribes of Taiwan, the Ami have characteristics intermediate between those of the Yami and the Bunun. The relative positions of these tribes in East Asian populations suggests that the extent of sinodontification and of genetic isolation is one of the causes of the intertribal variation.