Sex determination by three-dimensional geometric morphometrics of craniofacial form

Abstract

The purpose of the present study is to define which regions of the cranium, the upper-face, the orbits and the nasal are the most sexually dimorphic, by using three-dimensional geometric morphometric methods, and investigate the effectiveness of this method in determining sex from the shape of these regions. The study sample consisted of 176 crania of known sex (94 males, 82 females) belonging to individuals who lived in Greece during the 20(th) century. The three-dimensional co-ordinates of 31 ecto-cranial landmarks were digitized using a MicroScribe 3DX contact digitizer. Goodall's F-test was performed in order to compare statistical differences in shape between males and females. Generalized Procrustes Analysis (GPA) was used to obtain size and shape variables for statistical analysis. Shape, Size and Form analyses were carried out by logistic regression and discriminant function analysis. The results indicate that there are shape differences between the sexes in the upper-face and the orbits. The highest shape classification rate was obtained from the upper-face region. The centroid size of the caraniofacial and the orbital regions was smaller in females than males. Moreover, it was found that size is significant for sexual dimorphism in the upper-face region. As anticipated, the classification accuracy improves when both size and shape are combined. The findings presented here constitute a firm basis upon which further research can be conducted.

Application of Three Dimensional Geometric Morphometric Analysis for Sexual Dimorphism of Human Skull: A Systematic Review

“…However, the study also proved that the gnathic index was correlated with the changes in the height of cranial vault, and facial height or cranial flexion between the two regions, which is not anadequate measure for prognathism. 4,29 The inferior and posterior vault shape represented the greatest shape differences between sexes in the American Black. However, the nasal and the orbital area represented the latest distinctions.…”

“…20 Besides, Chovalopulou et al (2013) yielded 72% classification accuracy, 26 and revealed 81.8% and 84.3% classification accuracy in females and males, respectively. 29 Schlager and Rudell (2015) compared the variations on nose shape in the Germans and Chinese of both sexes by 3D geometric morphometric analysis on osseous tissue of the outer nose by utilizing the anatomical landmarks and semilandmarks. They investigated the discriminatory power of sexual dimorphism and the variations in population-specific shape concerning the bony nose on Chinese and German samples.…”

“…26 Chovalopulou et al (2016) examined the most common sexual dimorphic skull traits namely,forehead shape, orbits, nasal aperture, zygomatic bones and glabella to estimate their reliability for sexual dimorphism. 29 Moreover, they are useful components for determination of sex from skeletal remains in Greek population. They studied the validity and workability of geometric morphometric tools for estimation of sex.…”

“…26 According to Chovalopulou et al (2016), the upper-face shape analysis was a significant method for estimation of sex. 29 Nevertheless, there was a disagreement with Hennessy & Stringer (2002), who indicated no sexual dimorphism in the crania, which may be attributed to the small number of landmarks used. 43 Chovalopulou et al (2016) indicated that analysis of orbital region by shape was inaccurate for determination of sexual dimorphism.…”

“…The most common cranial measurements for sexual dimorphism included maximum length, maximum breadth, facial breadth, skull height, upper facial height and total facial height. 29 The aim of this study was to to determine the most sexually dimorphic parameters by geometric morphometric analysis of human skulls.…”