Evaluation of the Potential Use of Four Skull Traits for Sex Estimation

Background: Sex estimation is a basic step of human identification in both legal cases and archeological contexts. The highest accuracy for sex estimation is achieved when a complete skeleton is available, though there are situations, such as cremated, dismembered, and otherwise taphonomically altered skeletal remains, where a complete skeleton is not available. The aim of the present preliminary study was to evaluate the usefulness of four non-metric skull traits that are considered taphonomically resilient for sex estimation and their potential application in forensic cases. Methods: Non-metric skull traits of 100 skulls from the Bass Donated Skeletal Collection were analyzed. These traits included foramen magnum shape, zygomatic arch extension with respect to the external auditory canal, sigmoid notch, and gonial angle muscle attachment. A discriminant function analysis model was used to develop specific formulae for sex estimation. Results: The foramen magnum and sigmoid notch showed no significant differences between males and females. The zygomatic arch extension (ZAE) and gonial angle morphology (GO) showed strong, significant differences between the sexes. However, gonial angle morphology has shown to be affected by edentulism. Based on the ZAE, the function obtained by the discriminant function analysis was sex = 2.469*ZAE − 1.247, with a result of zero pointing to males and result of one pointing to females, which correctly classified 79.8% of the original cases. Conclusions: This study highlights the value of four different skull traits and their potential use in forensic cases. Of all the evaluated traits, zygomatic arch extension was the best indicator for sex estimation. This anatomical region corresponds to a highly resistant skeletal structure.