Sexual dimorphism in human browridge volume measured from 3D models of dry crania: A new digital morphometrics approach

Sex estimation from the human skull is often a necessary step when constructing a biological profile from unidentified human remains. Traditional methods for determining the sex of a skull require observers to rank the expression of sexually dimorphic skeletal traits by subjectively assessing their qualitative differences. One of these traits is the prominence of the glabellar region above the browridge. In this paper, the volume of the browridge region was measured from digital 3D models of 128 dry crania (65 female, 63 male). The 3D models were created with a desktop laser scanner, and the browridge region of each 3D model was isolated using geometric planes defined by cranial landmarks. Statistical analysis of browridge-to-cranium volume ratios revealed significant differences between male and female crania. Differences were also observed between geographically distinct populations, and between temporally distinct populations from the same locale. The results suggest that in the future, sex determination of human crania may be assisted by quantitative computer-based volume calculations from 3D models, which can provide increased objectivity and repeatability when compared to traditional forensic techniques. The method presented in this paper can easily be extended to other volumetric regions of the human cranium.