Morphometric analysis of pelvic sexual dimorphism in a contemporary Western Australian population
Requisite to routine casework involving unidentified skeletal remains is the formulation of an accurate biological profile, including sex estimation. Choice of method(s) is invariably related to preservation and by association, available bones. It is vital that the method applied affords statistical quantification of accuracy rates and predictive confidence so that evidentiary requirements for legal submission are satisfied. Achieving the latter necessitates the application of contemporary population-specific standards. This study examines skeletal pelvic dimorphism in contemporary Western Australian individuals to quantify the accuracy of using pelvic measurements to estimate sex and to formulate a series of morphometric standards. The sample comprises pelvic multi-slice computer tomography (MSCT) scans from 200 male and 200 female adults. Following 3D rendering, the 3D coordinates of 24 landmarks are acquired using OsiriX® (v.4.1.1) with 12 inter-landmark linear measurements and two angles acquired using MorphDb. Measurements are analysed using basic descriptive statistics and discriminant functions analyses employing jackknife validation of classification results. All except two linear measurements are dimorphic with sex differences explaining up to 65 % of sample variance. Transverse pelvic outlet and subpubic angle contribute most significantly to sex discrimination with accuracy rates between 100 % (complete pelvis—10 variables) and 81.2 % (ischial length). This study represents the initial forensic research into pelvic sexual dimorphism in a Western Australian population. Given these methods, we conclude that this highly dimorphic bone can be used to classify sex with a high degree of expected accuracy.
KeywordsSex discrimination Forensic anthropology Pelvic measurements Computed tomography Population standards Sexual dimorphism
The authors would like to thank A/Prof. Rob Hart, Frontier Medical Imaging International, Western Australia, for the assistance in obtaining the CT scans. We also offer our thanks to Dr Len Freedman and two anonymous referees for their helpful comments on this manuscript and to Dr. Allowen Evin for her fundamental help with the use of R. AC acknowledges the support of the Durham University Department of Anthropology and Durham International Fellowships for Research and Enterprise (DIFeREns) co-funded by Durham University and the European Union. We also acknowledge funding from a now completed ARC Discovery Grant (DP1092538) held by DF, AC and MKM.
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