Determination of the Pretreatment of Bone: A Macroscopic and Microscopic Approach to Fracture Patterns

Actualistic studies of bone can contribute to an understanding of cultural modification of archaeologically recovered bone. Two such cultural modifications include cooking and subsequent fracturing during food preparation. In an effort to understand the fracture dynamics and patterns of cooked bone, a three part study is undertaken including fresh, boiled, and roasted bone. This study incorporates mechanical stress testing of bone, hand-fracturing with study of macroscopic fracture details, and examination of surface morphology using a scanning electron microscope (SEM).

Results of this study indicate that macroscopic features such as texture, fracture class, impact point, presence of longitudinal fractures, and fractures that continue through the diaphyseal ends are not independent of pretreatment and should be noted during analysis. Changes in microscopic surface texture and the ability to view associated structures form a possible basis for the assignment of bone to its treatment class. Mechanical testing indicates that boiled and fresh bone can carry similar loads to first failure, although the degree of failure is more complete for fresh bone. The strength of boiled bone declines significantly with cooling. Roasted bone is significantly weaker than the other two groups.

This study may be applied to faunal assemblages and in some cases, physical anthropology. Prior to the advancement of a method to determine the treatment class of bone, however, post-depositional and diagenetic factors must be taken into account.