Geometric morphometric assessment of sexually dimorphic characteristics of the distal humerus.

A number of recent studies investigated the use of morphological characteristics of the distal humerus to estimate the sex of unknown individuals. Using visual assessment, accuracies ranging from 74% to more than 90% were reported. The aim of this study was to assess these traits with geometric morphometrics, in order to determine if they corroborate the findings described with pure visual assessment. A total sample of 155 female and 175 male humeri of South Africans were used. All humeri were photographed in standardized positions from a posterior and inferior view, and homologous landmarks assigned. Olecranon fossa shape, angle of the medial epicondyle and trochlear symmetry were assessed. Males and females could be separated with accuracies ranging from 78% to 91%. The results of this study confirm the existence of these traits and their usability in assessment of sex from skeletal remains, and the observed anatomical characteristics largely agree with what have been described by visual assessment.

A cross-sectional analysis of age related changes in the osteometric dimensions of long bones in modern South Africans of European and African descent.

New techniques are continuously developed to establish individualizing characteristics of unknown skeletonized remains. However, the critical evaluations of older, and seemingly standardized, methods are also necessary. Since many of the methods to determine skeletal sex are used in a medico-legal arena, the application of proper techniques to achieve accurate results is paramount. The purpose of this study was to evaluate whether the osteometric variables that are often used in discriminant function formulae to determine sex, namely the dimensions of the proximal and distal articular surfaces and the mid-shaft diameters of the long bones, increase or decrease with the advancement of age. Twenty-three standard anthropometric measurements were taken from the long bones of 404 male (n=106 white, n=298 black) and 189 female (n=82 white, n=107 black) known skeletons housed at the medical schools of the Universities of Pretoria and the Witwatersrand in South Africa. Results indicated that males and females of both ancestral groups were sexually dimorphic for the long bone measurements. The mean size of these measurements demonstrated a statistically significant increase in size from young to old groups in white females and males, with black females remaining static for their measurements and changes with age. Reasons for an increase in size are multi-faceted and may include normal degenerative changes such as bone remodeling, microfractures at articular joint surfaces, and changes in the relationship of cortical and endosteal bone as well as disease (osteoporosis). Males also increase in robusticity long after their epiphyses had closed. These changes may pose challenges to the accurate determination of sex should only metric characteristics be used.