No abstract

The mastoid process is one of the most sexually dimorphic features in the human skull, and is therefore often used to identify the sex of skeletons. Numerous techniques for assessing variation in the size and shape of the mastoid process have been proposed and implemented in osteological research, but its complex form still presents difficulties for consistent and effective analysis. In this article, we compare the different techniques and variables that have been used to define, measure, and visually score sexual dimorphism in the mastoid process. We argue that the current protocols fail to capture the full morphological range of this bony projection, and suggest ways of improving and standardizing them, regarding both traditional and 3D-based approaches.

No abstract

The frontal bone is one of the most sexually dimorphic elements of the human skull, due to features such as the glabella, frontal eminences, and frontal inclination. While glabella is frequently evaluated in procedures to estimate sex in unknown human skeletal remains, frontal inclination has received less attention. In this study we present a straightforward, quick, and reproducible method for measuring frontal inclination angles from glabella and supraglabella. Using a sample of 413 human crania from four different populations (U.S. Whites, U.S. Blacks, Portuguese, and Chinese), we test the usefulness of the inclination angles for sex estimation and compare their performance to traditional methods of frontal inclination assessment. Accuracy rates in the range 75-81% were achieved for the U.S. White, U.S. Black, and Portuguese groups. For Chinese the overall accuracy was lower, i.e. 66%. Although some regional variation was observed, a cut-off value of 78.2° for glabellar inclination angles separates female and male crania from all studied populations with good accuracy. As inclination angles measured from glabella captures two sexually dimorphic features (i.e. glabellar prominence and frontal inclination) in a single measure, the observed clear male/female difference is not unexpected. Being continuous variables, inclination angles are suitable for use in statistical methods for sex estimations.