Quantifying Male and Female Shape Variation in the Mastoid Region of the Temporal Bone

The shape of the temporal bone of the adult human cranium, specifically the mastoid region, is documented widely in past literature as a measure of sexual dimorphism within and among human populations. Yet, past research focus primarily on the qualitative assessment of the size of the mastoid region as it varies between males and females. This study explores both standard qualitative and standard and nonstandard quantitative measures of variation, in both size and shape, of the inferiorly projecting cone-shaped process of the temporal known as the mastoid process. A set of five measurements, two of which use five non-metric scores, compiled or developed at the Wichita State University Biological Anthropology Laboratory (WSU-BAL) to better characterize the mastoid region, are recorded for 100 male and 100 female adult crania from the Hamann-Todd collection at the Cleveland Museum of Natural History. Descriptive statistics demonstrate patterns of sexual dimorphism in the mastoid region and the results indicate that a quantitative approach provides greater consistency in identification than the qualitative characterization of the mastoid region, as it is used almost exclusively in current practice.