Exploring sexual dimorphism of the modern human talus through geometric morphometric methods

Abstract

Sex determination is a pivotal step in forensic and bioarchaeological fields. Generally, scholars focus on metric or qualitative morphological features, but in the last few years several contributions have applied geometric-morphometric (GM) techniques to overcome limitations of traditional approaches. In this study, we explore sexual dimorphism in modern human tali from three early 20th century populations (Sassari and Bologna, Italy; New York, USA) at intra-and interspecific population levels using geometric morphometric (GM) methods. Statistical analyses were performed using shape, form, and size variables. Our results do not show significant differences in shape between males and females, either considering the pooled sample or the individual populations. Differences in talar morphology due to sexual dimorphism are mainly related to allometry, i.e. size-related changes of morphological traits. Discriminant function analysis using form space Principal Components and centroid size correctly classify between 87.7% and 97.2% of the individuals. The result is similar using the pooled sample or the individual population, except for a diminished outcome for the New York group (from 73.9% to 78.2%). Finally, a talus from the Bologna sample (not included in the previous analysis) with known sex was selected to run a virtual resection, followed by two digital reconstructions based on the mean shape of both the pooled sample and the Bologna sample, respectively. The reconstructed talus was correctly classified with a P post between 99.9% and 100%, demonstrating that GM is a valuable tool to cope with fragmentary tali, which is a common occurrence in forensic and bioarchaeological contexts.

Sex- and age-related variations in the three-dimensional orientations and curvatures of the articular surfaces of the human talus

“…Sex differences in the navicular articular surface of the talus have been reported by Ferrari et al [17], who indicated that the female navicular articular surface of the talus was more twisted in the frontal plane and more curved than that in males. In contrast, a recent geometric morphometric studies [18][19][20] has not detected sex differences in the articular surface orientation of the talus. Hence, based on these previous studies, the sex-and age-related differences in the articular morphology of the talus are still under debate.…”

Sex- and age-related variations in the three-dimensional orientations and curvatures of the articular surfaces of the human talus

“…Sex differences in the navicular articular surface of the talus have been reported by Ferrari et al [17], who indicated that the female navicular articular surface of the talus was more twisted in the frontal plane and more curved than that in males. In contrast, a recent geometric morphometric studies [18][19][20] has not detected sex differences in the articular surface orientation of the talus. Hence, based on these previous studies, the sex-and age-related differences in the articular morphology of the talus are still under debate.…”

Unveiling an odd fate after death: The isolated Eneolithic cranium discovered in the Marcel Loubens Cave (Bologna, Northern Italy)

“…Therefore, the stepwise selected measurements were analysed by leave-one-out cross-validation linear discriminant analysis (LDA), using final discriminant functions to predict the sex of the MLC. Finally, the MLC was projected into the Principal Component Analysis (PCA) previously computed on the known sample to explore its proximity with one sex or the other, as already done with other bones [ 27 ]. The cranial metric dataset was analysed in R v. 3.6.2 [ 28 ].…”