A cross-population study of sexual dimorphism in the bony labyrinth

Previous research found sexual dimorphism in the bony labyrinth of a Greek population sample (Osipov et al.2013). This study intends to investigate the nature of this structure's sexual dimorphism across populations of diverse geographic origin and to identify the effect of inter-population variation on the accuracy of determining sex using the bony labyrinth. Three population samples of known sex were analyzed originating from Europe (n = 30), Africa (n = 38), and North America (n = 30). The discriminant function developed in Osipov et al. (2013) was applied, and new function equations for sex estimation were developed. In addition, we used principal component analyses for investigating population differences, while bivariate tests were used to compare across population samples, sexes, and anatomical sides. A significant level of sexual dimorphism was found in all population samples, being driven by both size and shape differences. Discriminant functions for sex estimation were developed for all three population samples combined (71.4% accuracy) as well as separately (70-80% accuracy). The German sample was the least sexually dimorphic, whereas the North American sample exhibited the greatest sexual dimorphism. The size and shape of the bony labyrinth also significantly differed across population samples. The bony labyrinth is found to be sexually dimorphic across distinct population groups. Due to significant differences across our population samples, the accuracy of the previously proposed method for sex determination (Osipov et al.,2013) was relatively low. For this purpose, this study presented new functions, whose accuracy was tested in three distinct population samples.