Long bone morphometrics for human from non-human discrimination

Abstract

Forensic anthropologists are frequently required to verify the human origin of complete and partial skeletal remains. This determination, however, can be difficult for bone fragments with few or no distinctive morphological markers. Current methods of distinguishing human from non-human bone fragments include microscopic, immunological and DNA testing, which are each limited to some degree (e.g. time consuming and expensive). The purpose of this study is to investigate an alternative morphometric approach to quantify the external structure of human long bones (humeri, femora, and tibiae) compared to quadrupedal (sheep, dog, and pig) and bipedal (kangaroo and emu) animals common to Australia. Eight traditional measurements were taken on a sample of 50 human and at least 10 of each of the five animal species; measurements were then analysed using linear discriminant analysis (LDA). The results expectedly indicate enough variation between species to correctly assign an unknown bone as that of a human or non-human, with cross-validated classification accuracy of 95% or better. More importantly, however, the technique also proved to be accurate if only a fragment of the diaphysis is analysed; classification accuracy 63-99%. The results of this study, therefore, outline a forensically useful non-invasive method to distinguish human from animal bones.