Sexual Dimorphism in the Tarsals: Implications for Sex Determination.

Abstract

The accurate determination of sex is the first analytic task of physical anthropologists in the study of human skeletal remains. Correct sex determinations are essential because most other skeletal analyses rely on this to be accurately determined. Although morphological features of the skull and pelvis have been traditionally used for sex determination, certain metric analyses have also been useful. In the absence of the most commonly used bones, metric measurements obtained from the tarsals have the ability to provide accurate information regarding sex. Metric sex assessments are based on the levels of sexual dimorphism between males and females. This thesis evaluates the presence of sexual dimorphism in the tarsals and their dimensions of length, width, and height and assesses which bones and dimensions are most useful for sex determination using a modern skeletal sample (n = 160) comprised of individuals of known sex and age. Summary statistics were calculated for males and females separately to assess the sexual variation for each measure. Pearson’s Correlation Coefficient was used to establish correlations between sex and each measurement. Logistic regression analysis was used to determine the levels of sexual dimorphism in the bones and dimensions for the sample. Accuracy of sex estimations was compared between the left and right sides for each bone to determine if one side was more sexually dimorphic than the other. Logistic regression coefficients from the most accurate bones and dimensions were generated from the sample, which can be used to develop equations to accurately sex other samples of similar Euro-American ancestry. The most sexually dimorphic tarsals were the talus and first cuneiform. Tarsals from the right side were slightly more sexually dimorphic than those from the left. Length and height dimensions were more variable than breadth dimensions. Correct classifications for individual variables were as high as 87.8 %, with the highest overall percentage of correct classification of 93.5% obtained from a combination of all height measurements from the right tarsals for the total sample. This has implications for sexing skeletal remains from archaeological samples when other more commonly used bones are absent or poorly preserved.