Sexual dimorphism in the humerus: A comparative analysis of Chinese, Japanese and Thais

Determination of sex from the skeleton is vital to medicolegal investigatio ns. There is no longer any question that populations differ in size and pro portions and these differences affect the metric assessment of sex. The ext ent of variation in sexual dimorphism among Asian Mongoloids within and bet ween regions has not been quantified by discriminant function analysis, nor have standards for most groups been introduced for the humerus. Therefore, the purpose of this research is to establish metric standards for sex dete rmination from the humerus of Chinese, Japanese and Thais, as well as to co mpare size and sexual dimorphism in these Asian Mongoloid populations. The database for this study consisted of documented skeletal samples from China (N=87), Japan (N=90), and Thailand (N=104). Six standard dimensions, inclu ding maximum length, vertical head diameter, minimum midshaft diameter, max imum midshaft diameter, midshaft circumference, and epicondylar breadth wer e taken and subjected to stepwise and direct discriminant function analysis . Of dimensions selected by the stepwise function, vertical head diameter a nd epicondylar breadth were the only elements common to all there groups. O verall, mean accuracies were highest using formulae produced by the stepwis e procedure and ranged from 86.8% in the Chinese to 92.4% in the Japanese t o 97.1% in the Thais. Group comparisons also revealed that while the Chines e had the largest measurements, they were the least dimorphic. The reverse was true for the Thais and the Japanese were intermediate on both counts. I n cross validation tests, classification accuracy decreased in all cases wh ere a formula from one group was applied to another. It was therefore concl uded even though all individuals were Asian Mongoloids, these regionally di verse populations exhibited significant metric differences that affect sex determination from the skeleton. These findings confirm those of previous s tudies that there is a need for group specific metric standards of assessme nt. (C) 1998 Elsevier Science Ireland Ltd. All rights reserved.