New method for sex prediction using the human non-adult auricular surface of the ilium in the Collection of Identified Skeletons of the University of Coimbra

Sex estimation in non-adult skeletons is crucial in bioarchaeology and forensic anthropology. It was not extensively considered in the past, mainly because it was stated that the dimorphic osteological features were difficult to identify before adulthood. Over the past few years, this statement was disproved, and the study of numerous dimorphic non-adult skeletal traits was approached. This paper presents a new methodology that evaluates the auricular surface of the non-adult ilia. Several morphological and continuous variables were recorded for 34 individuals (21 females and 13 males) aged between 7 and 18 from the Coimbra Identified Skeletons Collection (University of Coimbra, Portugal). The results show low intra and inter-observer errors for all the variables, which renders the methodology replicable. Two ratios related to the shape of the anterior area of the auricular surface offer the most dimorphic data (proportions of cases correctly assigned: 0.82 and 0.88; sexual allocation probabilities: 0.85 for both variables). A discriminant function and a logistic regression were developed, which correctly classified the 82.35 and the 88.23% of the individuals, respectively. Moreover, two qualitative variables, referred to as the overall morphology and the apex morphology, also show statistically significant differences between males and females (proportions of correct assignation: 0.82 and 0.76; sexual allocation probabilities: 0.79 and 0.76). These variables can be incorporated in a multifactorial approach together with other indicators already available in the specialised literature in order to help improve the accuracy of the results obtained. This methodological procedure has to be applied with other identified samples, including younger individuals, so as to test whether the trends presented in this context are maintained and are useful in populations from a different geographical provenience