Developing Subadult Sex Estimation Standards Using Adult Morphological Sex Traits and an Ontogenetic Approach

Forensic anthropologists routinely assist law enforcement agencies in the identification of unknown human skeletal remains by creating a biological profile, which consists of an estimate of a decedent’s sex, ancestry, stature, and age at death. Unfortunately, the only parameter of the biological profile that is routinely estimated for subadults is age at death, resulting in limited demographics to facilitate a positive identification. Research dedicated to subadult sex estimation has consistently reported low accuracy rates, likely because the methodological approaches are flawed and the samples are inappropriate. Techniques have largely focused on the skull and pelvis while utilizing individuals younger than 12 years of age despite the fact that these skeletal regions do not become substantially dimorphic until puberty. In contrast to previous research, the current proposal takes an ontogenetic approach to investigate the developmental trajectories of the skull and pelvic traits most commonly used for estimating sex in adults to determine their applicability in estimating sex in subadults. Morphological skull and pelvic data will be collected from ~1,000 full-body postmortem computed tomography scans of contemporary, known children from the United States between the ages of 8 and 20 years. Kruskal-Wallis with a Dunn’s test and Holm’s stepwise adjustment will be used to determine the age at which 1) the expression of each trait becomes significantly different between the sexes and 2) subadult and adult trait frequencies are comparable. Logistic regression will then be used to develop single and multiple variable classification models specifically for use with subadults. The models will be incorporated into graphical user interfaces (GUIs) and made freely available to forensic practitioners. While it is known that dimorphism in the skull and pelvis result from downstream consequences of puberty, the current study will allow for a better understanding of each trait’s unique developmental trajectory, quantify the predictive power of each trait in estimating sex throughout ontogeny, and inform forensic anthropologists of the age at which sex can be accurately estimated using the most commonly relied upon traits for adult sex estimation. Ultimately, this research will allow for the inclusion of sex in the subadult biological profile, effectively increasing the number of positive identifications in forensic contexts, and subsequently, improving outcomes in medicolegal death investigations. Note: This project contains a research and/or development component, as defined in applicable law, and complies with Part 200 Uniform Requirements - 2 CFR 200.210(a)(14). CA/NCF