Sexual dimorphism and biomechanical loading in occipital bone morphological variation

Abstract

This research explores the contribution of biomechanical activity to several metric and non-metric aspects of occipital bone variation. Previous studies note that occipital traits including robusticity and size can often be used to illicit estimates of ancestry and sex. The utility of occipital traits in fragmentary human remains for population affinity or sex however may be compromised by a previously unexplored contribution from biomechanical stress. Through the examination of traits highly associated with biological sex (foramen magnum area, external occipital protuberance depth, lambda-inion length, bicondylar breadth, occipital form, and nuchal line rugosity) this study examined the potential sex estimation against a reflection of gender specific lifestyle differences or changes in activity patterns over time in occipital dimensions. Directly collected data and previously published data were analyzed from several sites, including Archaic hunter-gatherers from Florida, Agricultural groups from South Dakota, and modern populations from FSU teaching collection and the Terry and Hamann-Todd collections. Findings suggest that the foramen magnum area is not sufficiently dimorphic amongst our samples to accurately estimate biological sex and significant inter-group variation in bicondylar breadth and lambda-inion may indicate activity related differences.

Testing of morphological sex estimation traits with a sex‐known collection: Ottoman period skulls

“…An increase in muscular mass may require a larger attachment area (Garvin, 2020). The nuchal crest can be influenced by environmental factors until adolescence and mechanical loads can alter its morphology (Hoover & Thomas, 2022;Zhang & Schepartz, 2021). The mastoid process, having multiple neck muscles, can be affected by biomechanical forces related to the flexion and rotation of the head (Boucherie et al, 2022).…”