Non-metric dental trait variation among local sites and regional groups of the Neolithic Jomon period, Japan

The eight diagnostic morphological traits of the Sundadont and Sinodont divisions of the Mongoloid dental complex are identified. Intra- and intergroup variation for these crown and root features is plotted. The univariate frequency distributions provide useful evidence for several suggestions about East Asian prehistory, dental microevolution, and intergroup relationships. The case for local evolution of Sundadonty is strengthened by finding Australian teeth to be very similar to this pattern. Australian Aboriginal teeth are also generally like those of Jomonese and some Ainus, suggesting that members of the late Pleistocene Sundaland population could have initially colonized Sahulland as well as the continental shelf of East Asia northward to Hokkaido.

This article uses metric and nonmetric dental data to test the "two-layer" or immigration hypothesis whereby Southeast Asia was initially occupied by an "Australo-Melanesian" population that later underwent substantial genetic admixture with East Asian immigrants associated with the spread of agriculture from the Neolithic period onwards. We examined teeth from 4,002 individuals comprising 42 prehistoric and historic samples from East Asia, Southeast Asia, Australia, and Melanesia. For the odontometric analysis, dental size proportions were compared using factor analysis and Q-mode correlation coefficients, and overall tooth size was also compared between population samples. Nonmetric population affinities were estimated by Smith's distances, using the frequencies of 16 tooth traits. The results of both the metric and nonmetric analyses demonstrate close affinities between recent Australo-Melanesian samples and samples representing early Southeast Asia, such as the Early to Middle Holocene series from Vietnam, Malaysia, and Flores. In contrast, the dental characteristics of most modern Southeast Asians exhibit a mixture of traits associated with East Asians and Australo-Melanesians, suggesting that these populations were genetically influenced by immigrants from East Asia. East Asian metric and/or nonmetric traits are also found in some prehistoric samples from Southeast Asia such as Ban Kao (Thailand), implying that immigration probably began in the early Neolithic. Much clearer influence of East Asian immigration was found in Early Metal Age Vietnamese and Sulawesi samples. Although the results of this study are consistent with the immigration hypothesis, analysis of additional Neolithic samples is needed to determine the exact timing of population dispersals into Southeast Asia. 2004 Wiley-Liss, Inc.

The origins of the four major geographical groups recognized as Australomelanesians, Micronesians, Polynesians, and East and Southeast Asians are still far from obvious. The earliest arrivals in Sahulland may have migrated from Sundaland about 40,000-50,000 years B.P. and begun the Australomelanesian lineage. The aboriginal populations in Southeast Asia may have originated in the tropical rain forest of Sundaland, and their direct descendants may be the modern Dayaks of Borneo and Negritos of Luzon. These populations, the so-called "Proto-Malays," are possible representatives of the lineage leading to not only modern Southeast Asians, but also the Neolithic Jomon populations in Japan. The present study suggests, moreover, that the Polynesians and western Micronesians have closer affinities with modern Southeast Asians than with Melanesians or Jomonese.