Ainu and Ryukyuan cranial nonmetric variation: Evidence which disputes the Ainu-Ryukyu common origin theory

Abstract

Presence or absence of 22 nonmetric traits was recorded in the crania from the islands of Amami, Okinawa, and Sakishima of the Ryukyu Islands. Their trait-frequency patterns were compared with the samples from East/Southeast Asia and the world using Smith's Mean Measure of Divergence (MMD) statistic, principal coordinate analysis, and neighbor-joining clustering algorithm. The results indicated that the Ryukyuan samples aligned with the East/Southeast Asian "Mongoloid" cluster and are far distant from the Jomon/Ainu cluster. These results do not support the prevailing view which favors a common origin of the Ainu and Ryukyuan peoples. Moreover, evidence based on morphological and genetic data supporting the present conclusion, and populational uniqueness of the Jomon and Ainu were discussed.