Sex estimation through geometric morphometric analysis of the frontal bone: an assessment in pre-pubertal and post-pubertal modern Spanish population

Abstract

Sex estimates is a key step of biological profile assessment in a forensic or anthropologic context. In this study, the sexual dimorphism of the frontal bone was analyzed to assess the accuracy of sex estimates using a geometric morphometric approach in a pre-pubertal and post-pubertal sample. The shape of the frontal bone was digitized on the lateral cephalograms of 87 pre-pubertal subjects (42 males, mean age 10.14, SD ± 1.48 years; 45 females mean age 10.02, SD ± 1.11 years) and 103 post-pubertal ones (53 males, mean age 29.33 SD ± 11.88 years; 50 females, mean age 26.77 SD ± 11.07 years). A generalized Procrustes analysis (GPA) was performed for shape analyses, filtering the effects of position, rotation, translation, and size. A principal component analysis (PCA) was performed on the GPA transformed variables, and a multiple logistic regression model was used to assess the accuracy of sex estimates. In both age groups, the average size of the centroid was significantly larger in males. The females presented shapes with a shorter distance between P2 (glabella) and P1 (supratoral) and a general narrowing of the structure on the sagittal plane. In the pre-pubertal group, the shape difference was not statistically significant. In the post-pubertal group, the mean shape was significantly different between the sexes. The method displayed a high accuracy for sex estimates (88.7% males, 90.3% females) also when applied in a validation sample (82.6% males and 94.1% females). The described morphometric analysis of the frontal bone is based on a limited number of landmarks, which allows sex estimates with high accuracy in post-pubertal subjects, while it is not applicable in pre-pubertal ones.

Predicting the eyebrow from the orbit using three-dimensional CT imaging in the application of forensic facial reconstruction and identification

“…1). The height of the orbit (measurement code 8, 9, 10) showed a higher correlation with the height of the upper border (measurement code 17,18,20,22,24,27) than the height of the lower border of the eyebrow (measurement code 19,21,23,25,26,28).…”

“…The general size of the orbit was larger in males; this is expected since the body size of males tends to be larger than females. Shape analysis, such as geometric morphometric analysis (GMM) has been applied to assess sex or ethnicity in other studies [26][27][28] . Future research should investigate sexual dimorphism and age change in Koreans using GMM, which was not dealt in this study.…”

Predicting the Eyebrow from the Orbit Using Three-dimensional CT Imaging: An Application in Forensic Facial Reconstruction and Identification

“…3). The height of the orbit (measurement code 8, 9, 10) showed a higher correlation with the height of the upper border (measurement code 17,18,20,22,24,27) than the height of the lower border of the eyebrow (measurement code 19,21,23,25,26,28).…”

“…Shape analysis, such as geometric morphometric analysis (GMM) has been applied to assess sex or ethnicity in other studies [25][26][27]. Future research should investigate sexual dimorphism and age change in Koreans using GMM, which was not dealt in this study.…”

Mapping sexual dimorphism signal in the human cranium

“…Most of the recent works focusing on cranial differences between sexes agree that sexual dimorphism signal is more marked if the analyses are performed on single populations than on a worldwide sample 25 , 31 – 33 . Despite the vast literature on this topic, protocols used day to day to classify individuals by sex are limited to empirical and visual morphological approaches.…”