Sex estimation from the long bones of modern South Africans

Abstract

Best scientific practice for sex estimation incorporates accurate techniques that employ appropriate standards and population- and period-specific data. Single measurements provide accurate sex estimations, but multiple measurements and multivariate techniques offer greater validity to biological profile assessments. Appropriate, modern standards for sex estimation are limited to the cranium in South Africans (SA), which warrants the examination of the potential for sex estimation using the postcrania of socially defined SA blacks, whites and coloureds through multivariate models and advanced statistical techniques. A total of 39 standard osteometric measurements were taken from the postcrania of 360 socially defined SA blacks, whites and coloureds (equal sex and ancestry). Univariate and multivariate models were evaluated. Multivariate models, with cross-validation and equal priors, were explored with linear and flexible discriminant analysis (LDA and FDA, respectively). Classification accuracies associated with univariate models ranged from 56 to 89%, whereas multivariate classification accuracies using bone models (i.e. all measurements from one element) ranged from 75 to 91%. The highest correct classifications were achieved with multivariate subsets (i.e. combinations of measurements from different bones) and ranged from 90 to 98%. Overall, FDA and LDA yielded similar accuracy rates. Postcranial bones achieve comparable classification accuracies to the pelvis and higher accuracies than metric or morphological techniques using the cranium. While LDA is the most commonly used classification statistic in biological anthropology, FDA provides a good alternative for classification.