Investigating Cranial Variation in Japanese Populations Using Geometric Morphometrics

The Japanese archipelago exhibits an immense amount of variation in culture and history, despite the lay population mostly considering the modern Japanese a homogeneous population. Japan has experienced an amazing amount migration activity. These migration events are well represented in the archaeological record and have provided fodder for hypotheses proposed for peopling of the new world.

Biological anthropologists have tested hypotheses surrounding the initial peopling of the islands using linear data in conjunction with non-metric traits of the skull. Recent molecular studies have provided evidence for population substructure, which suggests an original founding group of North Asian descent, and a more recent migration into Southern Japan from the Korean peninsula. The secondary migration interbred with the indigenous Jomon inhabitants, ultimately giving rise to two distinct genetic lineages.

An examination of a variety of skeletal collections from a range of temporal and regional samples in Japan allows for an expansion of hypotheses proposed by previous research to explain the range of variation observed through time and space in Japan. This study aims to build upon research endeavors that have quantified various aspects of skeletal morphology represented in Japan. This study reexamines the majority of analyses that have used metric data by using three dimensional data (3D). 3D or coordinate data can be used to better identify evolutionary patterns in biological populations via geometric morphometric approaches. Samples utilized represents skeletal collections of a nearly temporally continuous sequence that encompasses the indigenous Jomon culture that dates to 10,000 BP to the modern period.

Results highlight the utility of comparisons of various types of data that represent morphological variation. It is argued that 3D data can provide novel results and thus the reexamination of a host of hypothesis that examine morphology of the cranium is warranted.