Age estimation from features of the first rib

Abstract

Several techniques for estimating adult age-at-death are used in biological and forensic anthropology, including morphological changes of the ribs. However, due to human variation and taphonomic damage, it remains difficult to produce accurate and meaningful age-at-death estimations based on skeletal remains. This research further explores morphological changes to the first rib, which is easily identifiable and relatively robust, including the costal face and tubercle facet identified by Kunos’ (1999) and modified by DiGangi et al. (2009). A total of 400 European American individuals (f=200; m=200) from the William M. Bass Donated Skeletal Collection at the University of Tennessee, Knoxville, were observed using modified descriptions for Kunos’ (1999) five traits of the costal face and tubercle facet, on an ordinal scale of 1-8. Additionally, bone quality was assessed on an ordinal scale of 1-3 and was incorporated as a variable in order to improve estimations. Exploratory statistical analysis demonstrates that all eleven traits correlate with age at a statistically significant level, with bone quality being the most significant feature for both sexes. Female and male differences were found, and cross-validated ordinal logistic regression equations are presented for each. The resulting AIC table estimates 100% of the male and female sample correctly, though the produced ranges are too large to be forensically relevant. The results of this research underscore the importance of developing age estimation methods on skeletal regions that are under researched and for those that are more resistant to taphonomic damage.