Sex determination from the metacarpals in a modern South African male and female sample

Abstract

Forensic anthropological studies include the determination of demographic characteristics such as sex. Parts of the human skeleton that are accurate predictors for sex include the skull, pelvis, femur and tibia. Metacarpals were previously excluded from studies on sexual dimorphism due to their relatively small size and often poor preservation. Scheuer and Elkington (1993) have shown that metacarpals (MC) are sexually dimorphic, with accuracies ranging from 78 to 92%. The aim of this study was to develop discriminant function formulae to determine sex from the metacarpals in a South African population. Metacarpals of 200 individuals, which comprised 50 individuals from each sex-race group (blacks, whites, males and females), were used. Seven measurements on each bone were recorded with a caliper to an accuracy of 0.01mm. Data were analyzed using SPSS version 11.5. Stepwise discriminant functions were performed using all seven variables for each metacarpal bone. Only those variables that best distinguished between the sexes were selected and subjected to direct discriminant analysis. Statistically significant differences (p<0.0001) were found between males and females for all variables. In the stepwise discriminant function the following variables were selected first: the medio-lateral diameter for the first metacarpal, the antero-posterior measurement of the base for the second, third and fourth metacarpals and the antero-posterior measurement of the head for the fifth. Classification accuracy using the stepwise analysis ranged between 76% and 87%, with highest accuracies obtained for MC1. Accuracies for cross-validations were similar. Direct analyses using single variables produced accuracies ranging from 71% to 78%. Measurements of the metacarpals appear to be moderate discriminators of sex with overall classification accuracies ranging between 76.9 and 85.4%. These formulae can be used to determine sex should only single hand bones be found.