Evaluating the morphological and metric sex of human crania using 3-dimensional (3D) technology

Identifying the skeletal remains of an unidentified individual is a priority for the medico-legal system because identification increases the chances of finding the person responsible and provides closure to the family. The purpose of this research was to develop a combined morphological and metric cranial sex assessment method using 3D technology that accommodates the medico-legal system, and their use of 3D models facilitates the technological transition to digitally archived skeletal collections. A total of 91 individuals of European biogeographical ancestry from the William M. Bass Donated Skeletal Collection (University of Tennessee Knoxville) were imaged using photogrammetry, turned into 3D models using Agisoft PhotoScan, and digitally evaluated using 3D Studio Max. This novel method digitally evaluated five cranial traits, including the nasal aperture height, nasal aperture width, mastoid length, the general size and architecture, and the supraorbital ridges, combining techniques that can only be done digitally with those that can be completed on the actual bone. Preliminary statistical tests demonstrate an overall accuracy rate of 90% when tested against the training sample (20 males, 20 females) and 75% when tested against the test sample (51 individuals). Although no intra- or inter-observer error rate tests were done, and further testing on other skeletal collections is necessary, this method allows forensic anthropologists to perform relatively easy point-to-point measurements, the quantification of traditionally non-quantified traits, the possibility of reproducible results, and the ability for future analyses or research.