Ethnogenesis and craniofacial change in Japan from the perspective of nonmetric traits

Abstract

To examine population affinities in light of the 'dual structure model', frequencies of 21 nonmetric cranial traits were analyzed in 17 prehistoric to recent samples from Japan and five from continental northeast Asia. Eight bivariate plots, each representing a different bone or region of the skull, as well as cluster analysis of 21-trait mean measures of divergence using multidimensional scaling and additive tree techniques, revealed good discrimination between the Jomon-Ainu indigenous lineage and that of the immigrants who arrived from continental Asia after 300 BC. In Hokkaido, in agreement with historical records, Ainu villages of Hidaka province were least, and those close to the Japan Sea coast were most, hybridized with Wajin. In the central islands, clines were identified among Wajin skeletal samples whereby those from Kyushu most resembled continental northeast Asians, while those from the northernmost prefectures of Tohoku apparently retained the strongest indigenous heritage. In the more southerly prefectures of Tohoku, stronger traces of Jomon ancestry prevailed in the cohort born during the latest Edo period than in the one born after 1870. Thus, it seems that increased inter-regional mobility and gene flow following the Meiji Restoration initiated the most recent episode in the long process of demic diffusion that has helped to shape craniofacial change in Japan.

Craniometric divergence history of the Japanese populations

“…The view that the Jomon in Hokkaido were the probable major ancestors of the Ainu has been supported by many researchers (e.g. Turner, 1976;Yamaguchi, 1982;Ishida, 1990Ishida, , 1992Ishida, , 1993Kozintsev, 1992;Ishida and Dodo, 1997;Pietrusewsky, 1999Pietrusewsky, , 2000Pietrusewsky, , 2004Dodo and Kawakubo, 2002;Shigematsu et al, 2004;Fukumine et al, 2006;Ossenberg et al, 2006). Dodo and Kawakubo (2002), as well as the simple "dual-structure model" (Hanihara K., 1991), hypothesized that the Ainu in Hokkaido are the direct descendants of the Jomon without the effects of admixtures such as from the Yayoi.…”

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

“…It is generally agreed, based on cranial and dental morphology, that Jomon period populations are direct ancestors of the Hokkaido Ainu (e.g. Howells, 1966;Turner, 1976;Brace and Nagai, 1982;Yamaguchi, 1982;Hanihara, 1985Hanihara, , 1991Dodo, 1986;Mouri, 1986;Matsumura, 1989Matsumura, , 1994Matsumura, , 1995aDodo and Ishida, 1990;Pietrusewsky, 1994Pietrusewsky, , 2004Ossenberg et al, 2006). Geographical variation in Jomon period material has been investigated by several researchers and only minor differences have been found in the cranial morphology of samples dating from the middle to final Jomon periods (ca.…”

Interpretation of craniometric variation in northeastern Japan, the Tohoku region

“…The intensely studied population history of Japan has elucidated the origin and the process of differentiation of the present inhabitants of the Japanese archipelago (Yamaguchi, 1982(Yamaguchi, , 1992Turner, 1987Turner, , 1990Mizoguchi, 1988;Brace et al, 1989;Hanihara, 1991;Dodo and Ishida, 1992;Ossenberg, 1992;Ossenberg et al, 2006). Modern Japan has two related but morphologically and genetically distinguishable ancestral populations: the Jomon people, Neolithic hunter-gatherers; and migrants from eastern Asia to the southwestern part of Japan via the Korean Peninsula, who brought rice agriculture and metal-tool technologies (outlined by Hanihara, 1991;Dodo and Ishida, 1992;Yamaguchi, 1992).…”

“…Modern Japan has two related but morphologically and genetically distinguishable ancestral populations: the Jomon people, Neolithic hunter-gatherers; and migrants from eastern Asia to the southwestern part of Japan via the Korean Peninsula, who brought rice agriculture and metal-tool technologies (outlined by Hanihara, 1991;Dodo and Ishida, 1992;Yamaguchi, 1992). After the end of the Jomon period, during the subsequent Aeneolithic Yayoi and protohistoric Kofun periods, admixture between the indigenous people and the incoming populations blurred the distinction between the two populations (Turner, 1987(Turner, , 1990Brace et al, 1989;Brace and Hunt, 1990;Dodo and Ishida, 1990;Kozintsev, 1990Kozintsev, , 1992Hanihara, 1991;Lahr, 1996;Ossenberg et al, 2006).…”

“…The impact of the post-Jomon migrants was not, however, uniform throughout the Japanese archipelago (Hanihara, 1985(Hanihara, , 1991Ossenberg, 1986;Horai and Omoto, 1998;Ossenberg et al, 2006). The available skeletal and genetic data have suggested a stepwise process of differentiation and diversification of the physical traits, without complete disappearance of the Jomon characteristics (Yamaguchi, 1982(Yamaguchi, , 1992Horai and Matsunaga, 1986;Hanihara, 1991;Brace and Hunt, 1990;Turner, 1990;Dodo and Ishida, 1992;Tajima et al, 2004).…”