Taphonomic Agents and their Effects on Striated Toolmarks in Bone

Abstract

Forensic taphonomy is the study of any postmortem processes that affect remains from death until they are recovered. Taphonomy is a relatively new area to forensic science and researchers only beginning to understand its potential to modify human remains. The aim of this research was to determine whether or not environmental conditions could change toolmarks in defleshed bones. Striated toolmarks were produced by using the sharp edge of a wood chisel on Sus scrofa femora. All toolmarks were cast with Mikrosil® casting material and retained for later comparison to the respective exposed toolmark. Groups of bones were then placed in one of the following environmental conditions; laboratory, native bush, soil, stream and an intertidal marine environment. These bones were removed at weekly intervals for the first month and then monthly for the next five months. Upon removal the toolmarks were recast using Mikrosil® and compared to their original toolmark using the comparison macroscope. Percent of matching lines were calculated to record if any changes observed to the toolmarks after being exposed to an environmental condition. In all the outdoor environmental conditions the bones exhibited deterioration of the toolmarks during the six months of exposure. At the end of six months exposure, 30%, 38% and 54% of the original matching striae were lost from toolmarks in bone which had been weathered in the bush environment, buried and placed in the intertidal marine environment, respectively. Bones that had been exposed to the running water of the stream lost all striae after three months. The toolmarks in the bones placed in the laboratory did not change during the six month period. The results of these experiments showed that there is the potential to rapidly lose toolmark detail from bones which been exposed to an external condition.