Heat-induced dimensional changes in bone and their consequences for forensic anthropology

An understanding of heat-induced transformation of hard tissue is vital before a full interpretation of burned human remains can be successfully achieved. Samples of modem sheep (n = 60) were analyzed resulting in 5440 data points. An experimental approach was undertaken that explored the bi-variable impact of heating temperature and duration of burning. Subsequent heat-induced bone changes included the progression of color from natural through to blue-white, the significant loss of weight, the reduction in mechanical strength, the development of distinct fracture patterns, alterations in the microscopic porosity, substantial alterations in crystalline structure and reduction and expansion in size. Collation and integration of this information demanded a revision of the four stages of heat-induced degradation of bone previously presented by Mayne Correia (1) and Thompson (2). The results demonstrate that heat-induced shrinkage is also accompanied by expansion and that both can be statistically significant. This suggests that anthropological techniques applied to burned bone will likely be detrimentally affected and accuracy will be reduced.     

A New Method to Pair‐match Metacarpals Using Bilateral Asymmetry and Shape Analysis

Matching pairs of skeletal elements is of fundamental importance when re‐associating skeletons from commingled settings. This study presents a new method that combines the use of traditional anthropometric size measurements and the analysis of shape, through geometric morphometrics, to form pairs from commingled settings. We tested the hypothesis that shape asymmetry among individuals is smaller than between individuals that share similar dimensions. The metacarpals were measured in their maximum length, and absolute means of asymmetry between right and left metacarpals were calculated. To analyze the shape characteristics, two‐dimensional landmarks were recorded from digital images of 111 metacarpals. The specimens were analyzed using generalized Procrustes analysis and multivariate statistics. The accuracy of pair‐matching bones using a combined method was of 100%, showing that the incorporation of geometric morphometrics techniques—in the assessment of shape in physical anthropology—is of particular use when comparing the shape differences/similarities between individuals.