Morphology of Sexually Dimorphic Cranial Traits in Postmenopausal Females

Sexually dimorphic morphoscopic traits of the cranium are used to estimate sex with a high degree of accuracy. Researchers have suggested that postmenopausal females (>50 years of age) express more robust cranial features than younger females, particularly a more robust glabellar region, that may result in misidentification of older females as males. However, no scientific studies have substantiated this theory. The purpose of this study is to determine if morphoscopic cranial traits in postmenopausal females are more robust than in younger females. Five cranial traits were scored on 220 American White crania from the William M. Bass Donated Skeletal Collection at the University of Tennessee: nuchal crest, mastoid process, supra‐orbital margin, glabella and mental eminence. Sex and age (range=20‐94 years) were undisclosed during the scoring process to control for bias. The sample was broken into four cohorts for statistical analyses: 55 males and 55 females >50 years of age and 55 males and 55 females 蠄50 years of age. Two‐sample Kolmogorov‐Smirnov tests were used to compare the frequency distributions of the traits between the cohorts. The only trait with a significantly different distribution between pre‐ and postmenopausal females was the nuchal crest (p=0.032), with females 蠄50 yrs old presenting with more prominent nuchal crests on average. The data suggests that American White postmenopausal females do not exhibit more robust glabellas or other cranial traits, therefore contradicting the current published theory. Since the degree of sexual dimorphism is known to vary between populations, further studies should be done to explore these findings across demographics.