119(O5) Nonmetric cranial variation of Jomon Japan: implication for the evolution of eastern Asian diversity

A number of studies have shown that the prehistoric Jomon populations clearly differ from modern Japanese and eastern Asians, then supposed ancestors, and sister groups. In this study, R-matrix approach was applied to 20 nonmetric cranial traits for reconstructing the population history of the Jomon. Hokkaido region is the most diverse, and the diversity of Honshu Jomon is negatively correlated with their differentiation towards groups from Hokkaido except for Chugoku region. Such pattern of decrease in phenotypic diversity suggests a history of colonization of the Jomon population in Japanese archipelago characterized by a number of bottlenecks and limited gene flow. The larger variants of Chugoku region than those of eastern Japan suggest a possible gene flow from outside source. The splitstree analyses including samples from major geographic regions of the world indicate northern, and to a lesser extent southern, affinities of the Jomon and a separation of Southeast Asian samples from Northeast Asian series. These support complex population history for the peopling of Northeast Asian region rather than simple northward migration of Southeast Asians. Studying the population structure of the Jomon people may provide crucial clues to the peopling of not only the Japanese archipelago but also East/Northeast Asian region.