Biological relationships between the Jomon-Ainu and Pacific population groups were investigated through statistical analyses of the following 5 cranial indices: length-breadth, length-height, upper facial (after Kollmann), orbital and nasal indices. Data sets analyzed were consisted of 25 representative populations from Japan, Polynesia, Micronesia, Melanesia, and East Asia. The results supported a diffusion model supposed by many anthropologists as well cluster model proposed by Brace and colleagues and Katayama's similar hypothesis. The former 2 models stress the migration of both Pacific and Jomon-Ainu groups from somewhere in Southeast Asia, while the latter emphasizes a direct lineage from the Jomonese to the Pacific group. It was also confirmed that Java may have been part of a diffusion center from where the migration to the Pacific and Pacific-rim areas had taken place.
Hanihara et al. (1993) studied this question.