Brachycephalization in Japan has ceased.

Abstract

Somatometric data are presented which show that the rapid brachycephalization in Japan has recently ceased. The causes of brachycephalization are investigated in relation to the secular change in height. Increases in head breadth have been the main cause of brachycephalization, and its pattern of secular change is very similar to that in height. Associations between head breadth, height, and year of birth were examined by partial correlation coefficients and through a comparison of students and the general population. Brachycephalization is thought to result from increases in the growth rate for head breadth caused by improvements in nutritional levels, as seen in increases in height. Increases in height over the last 100 years have been accompanied by brachycephalization in Japanese and Koreans, but by debrachycephalization in many European populations. Increases in lateral growth in Asian heads may be related to the facial flatness which is characteristic to northern Mongoloid populations.