The application of traditional and geometric morphometric analyses for forensic quantification of sexual dimorphism: preliminary investigations in a Western Australian population

Abstract

A current limitation of forensic practice in Western Australia is a lack of contemporary population-specific standards for biological profiling; this directly relates to the unavailability of documented human skeletal collections. With rapidly advancing technology, however, it is now possible to acquire accurate skeletal measurements from 3D scans contained in medical databases. The purpose of the present study, therefore, is to explore the accuracy of using cranial form to predict sex in adult Australians. Both traditional and geometric morphometric methods are applied to data derived from 3D landmarks acquired in CT-reconstructed crania. The sample comprises multi-detector computed tomography scans of 200 adult individuals; following 3D volume rendering, 46 anatomical landmarks are acquired using OsiriX (version 3.9). Centroid size and shape (first 20 PCs of the Procrustes coordinates) and the inter-landmark (ILD) distances between all possible pairs of landmarks are then calculated. Sex classification effectiveness of the 3D multivariate descriptors of size and shape and selected ILD measurements are assessed and compared; robustness of findings is explored using resampling statistics. Cranial shape and size and the ILD measurements are sexually dimorphic and explain 3.2 to 54.3 % of sample variance; sex classification accuracy is 83.5-88.0 %. Sex estimation using 3D shape appears to have some advantages compared to approaches using size measurements. We have, however, identified a simple and biologically meaningful single non-traditional linear measurement (glabella-zygion) that classifies Western Australian individuals according to sex with a high degree of expected accuracy (87.5-88 %).

Estimation of sex from the metric assessment of digital hand radiographs in a Western Australian population

“…Misclassification may have a flow on effect that reduces the accuracy of the estimation of other biological attributes and ultimately compromise the identification of an individual. Population specific sex estimation standards afford the most accurate possible classification [11,21,28]. Within a forensic context it is particularly important to subject results to statistical interrogation and supply the end-user with a measure of sexual dimorphism and a quantification of the accuracy of the sex estimation standards developed.…”

“…Sex is often the first component of the biological profile estimated and the remaining elements (age and stature) are generally assessed using sex-specific methods [1,28]. Misclassification may have a flow on effect that reduces the accuracy of the estimation of other biological attributes and ultimately compromise the identification of an individual.…”

Quantification of the timing of anterior fontanelle closure in a Western Australian population

“…13 Thus, with current global migration patterns, and genetic admixture between previously separated groups, these skeletal collections may no longer be representative of contemporary populations. 13 In the analysis of human growth, the statistical quantification of the timing of the attainment of developmental milestones (such as the initial appearance of ossification centres and their subsequent fusion) can be affected by a variety of intrinsic and extrinsic factors, which include (but are not limited to) access to adequate nutrition, disease and illness susceptibility, and the level of socio-economic development (see Delemarrevan de Waal 14 ; Schmeling, Olze, Reisinger and Geserick 15 ; and Simondon, Simon and Simondon 18 ). Severe childhood illness and malnutrition can retard skeletal growth and development due to insufficient nutrients necessary for bone growth and will, therefore, affect the age at which children attain developmental milestones.…”

Sexual dimorphism of sternum using computed tomography – volume rendering technique images of Western Chinese

“…In addition, populations may experience secular variation, thus requiring the use of temporally representative skeletal collections in the derivation of anthropological standards, including those for the discrimination of sex 9,10 . Therefore, the objective of the current study was to develop population-specific discriminant function equations for predicting sex from measurements of the sternum in contemporary Western Chinese.…”