Exploring sexual dimorphism of human occipital and temporal bones through geometric morphometrics in an identified Western‐European sample

Abstract

Sex estimation is a paramount step of bioprofiling in both forensic anthropology and osteoarchaeology. When the pelvis is not optimally preserved, anthropologists commonly rely on the cranium to accurately estimate sex. Over the last decades, the geometric morphometric (GM) approach has been used to determine sexual dimorphism of the crania, in size and shape, overcoming some difficulties of traditional visual and metric methods. This article aims to investigate sexual dimorphism of the occipital and temporal region through GM analysis in a metapopulation of 50 Western-European identified individuals. Statistical analyses were performed to compare centroid size and shape data between sexes through the examination of distinct functional modules.Regression and Procrustes ANOVA were used to examine allometric and asymmetrical implications. Discriminant functions, combining size and shape data, were established.Significant dimorphism in size was found, with males having larger crania, confirming the major influence size has on cranial morphology. Allometric relationships were found to be statistically significant in both right and left temporal bones while shape differences between sexes were only significant on the right temporal bone. The visualization of the mean consensus demonstrated that males displayed a larger mastoid process associated with a reduced mastoid triangle and less projected occipital condyles. This exploratory study confirms that GM analysis represents an effective way to quantitatively capture shape of dimorphic structures, even on complex rounded ones such as the mastoid region. Further examination in a larger sample would be valuable to design objective visualization tools that can improve morphoscopic sex estimation methods.

Test of the lateral angle method of sex estimation on Anglo‐Saxon and medieval archaeological populations with genetically estimated sex

“…This variability, as is evident from the anterior LA results in this study, cannot be explained by sexual dimorphism (Duquesnel Mana et al, 2016). Although there is sexual dimorphism in the temporal bone and cranial base (e.g., Boucherie et al, 2022), discriminant functions developed from these regions typically fail to perform accurately when they are subsequently applied to populations unrelated to those on which the methods were developed (Inskip et al, 2018; Pezo‐Lanfranco & Haetinger, 2021; Uhl et al, 2020). It is therefore not surprising that the IAC anterior angle sectioning point developed on a forensic sample population has failed to estimate sex among Anglo‐Saxon and Medieval inhabitants of Cambridgeshire.…”

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

“…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). The glabella is the attachment region for muscles involved in eye closure and downward pulling of the eyebrows (Godde, 2015).…”