The analysis of rodent gnawing

Abstract

As the post-mortem interval (PMI) of human remains increases over a long period of time it becomes increasingly difficult for forensic anthropologists to determine how long since the remains have been deposited. There has been research establishing the PMI from taphonomic features that affect human remains. However, there is still some debate over the best process for forensic anthropologists to use to establish the PMI. It has been observed in various cases that rodent gnawing occurs on bones of many large vertebrates. Previous research has also demonstrated that certain rodents will gnaw on bone in various stages of decomposition and understanding which rodents gnaw on bones at which stage of decomposition could be used to help establish PMI. The present investigated the presence and timing of rodent activity on bone and the comparison of incisor widths from various rodent species to identify the species of rodent that gnaw on particular bones. It is hypothesized that this type of data could be used as a method to determine a PMI. Two complete porcine carcasses and bones from fourteen pigs were used in this study to obtain rodent gnawing marks on the bones. However, rodent activity was not observed on the remains during the time of exposure (six months). Therefore in addition, maxillary and mandibular incisor measurements were obtained from multiple rodent skulls (n = 160) of multiple taxa from the Zooarchaeology Laboratory and Mammalology Department at Harvard University. Univariate analysis was performed on these measurements to test for significant differences between rodent species. The results showed that while there were differences in the widths between the incisor measurements taken at Harvard University when compared to the measurements taken from the rodent impressions. Therefore, the size of the widths can still be used to correspond to certain rodent species. More research is needed to determine if the use of rodent gnawing on bones is a viable option for estimating PMI.