Sexual dimorphism in modern Japanese crania

Abstract

The Japanese population has gone through significant micro-evolutionary changes during the last half century. One approach to quantify these changes is an osteometric analysis of sexual variation in the skeleton. The present study evaluates sexual dimorphism in modern Japanese cranial dimensions. Comprehensive osteometric data were obtained from 84 modern Japanese skeletons of known sex and age at death from the dissecting room collection at Jikei Medical University, Tokyo. The remains were macerated between 1960 and 1970 and thus are from individuals who lived through World War II. A total of 16 cranial dimensions were subjected to SPSS-X discriminant function analysis. Using 11 measurements of the cranium, five dimensions were selected by the stepwise discriminant methods, including bigonial breadth. In a second stepwise function using 11 cranial measurements, seven contributed to the function. In both functions, mastoid height was selected first and prediction accuracy averaged 84%. Because of its significant contribution, a function was calculated from mastoid height alone. This produced an average of 74% prediction accuracy. In general, width dimensions better reflected differences between the sexes. The accuracy of correct classification from the Jikei sample was slightly lower than those of earlier Japanese populations. The results of this study also suggested that sexual dimorphism in Japanese crania may have decreased as a result of an increase in size of females. © 1995 Wiley-Liss, Inc.