A closer look at density mediated attrition: relationships between pathology, taphonomy, and preservation

Accurate information as to how taphonomy effects skeletal material with varying degrees of structural integrity and density is vital to current understandings of preservation. Interaction effects can assist with research design, as well as excavation and curation strategy. To this purpose, the current study focuses on the interactions between pathological and taphonomic variables, with a special focus on density and preservation. It was hypothesized that (1) preservation trends related to density present in the literature would be reflected in the sample data, (2) pathological variables that increase bone density would be more resistant to individual taphonomic processes while pathological variables that decreased bone density would be more vulnerable, and (3) the common practice of excluding elements under fifty percent preservation would significantly reduce prevalence rates, especially of variables that decrease bone density. Data collection was undertaken on three samples; forty-one individuals from the Santa Clara Valley Medical Center (VMC) collection and twelve individuals from the CSUC modern collection, both housed at California State University, Chico. In addition, twenty-four unidentified individuals housed at the New York City Office of the Chief Medical Examiner were examined. Preservation rates, using two recording methods, were assessed for associations with sex, age, and element type. Pathological variables were then compared to taphonomic variables to assess interactions. The final analysis compared preservation rates before and after removal of elements under fifty percent present to establish any significant differences. The results suggest that the preservation trends in the sample data do not directly reflect those present in the literature, although general trends do lean in that direction. The results of the association tests between pathological and taphonomic variables reveal that bone removing processes were related to decreased vulnerability for a number of taphonomic processes. While this result is possibly a product of the samples used, it perhaps indicates that the interaction between pathology and taphonomy encompasses more than just density. Testing of the final hypothesis revealed that there was only a significant difference in prevalence rates before and after removal of elements under fifty percent present occurred in the bone building/stasis category. These results highlight the importance of continued research in how taphonomic processes interact with skeletal material on an individual level. This research also calls into question the practice of removing elements from analysis based on preservation and presents an alternative based on smaller units of comparison. While further research on this topic is necessary, this study represents a beginning in the understanding the complexity of taphonomic interaction.