Ontogenetic Study of the Pelvis Through Examination of Interlandmark Distances and Geometric Morphometric Analyses: Implications for Subadult Sex and Age Estimation

The human pelvis is extensively relied upon by forensic anthropologists for age and sex estimations of unidentified skeletal remains. However, subadult individuals are an underrepresented demographic in skeletal collections. Without data sources, there is a concomitant lack of ontogenetic knowledge of the sub-elements (ilium, ischium, and pubis) and the overall pelvic complex. Without knowledge, there is a lack of understanding of the onset of sexually dimorphism and/or age-related size and shape changes. The purpose of this research is to provide a detailed analysis of modern human pelvic growth using in situ pelvic landmarks and subsequent size (interlandmark distances) and shape (geometric morphometric) variables to understand how age and sex impact the ontogeny of the pelvis. It is expected that the size and shape of the pelvis stabilizes at a younger age than previously assumed and subsequently the pelvic phenotype has an increased utility in the subadult biological profile, specifically age and sex estimation.

Two virtual anthropology sources will be used, the Subadult Virtual Anthropology Database (SVAD) and the New Mexico Decedent Image Database (NMDID). The contemporary United States sample in SVAD enables data collection on ~1000 individuals between the ages of 0 and 20 years, and the additional NMDID data enables data collection on individuals between the ages of 20 and 30 years. Thirty-four pelvic landmarks on the left and right segmented surface models lead to 68 landmarks per individual. Standard and non-standard interlandmark distances will be used in sex-specific and pooled-sex nonlinear regression models. Geometric morphometric analyses will be performed on the ilium, ischium, pubis, and innominate (post-fusion) to understand shape variation through ontogeny. Lastly, the size and shape variables will be used in a mixed cumulative probit (MCP) algorithm to estimate age and flexible discriminant analysis (FDA) to estimate sex.

Successful subadult sex and age estimation models utilizing pelvic metrics will be incorporated into graphical user interfaces and added to KidStats for easy application. The current study is a unique opportunity to conduct innovative and novel research on the most complex and informative postcranial skeletal element leading to a transformative impact on the field and broader impacts in a variety of disciplines. CA/NCF