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The Value of Nonhuman Animal Models in Forensic Decomposition Research

Scientific inquiry into the process of decomposition has studied a wide range of mammals and developed a fundamental understanding of the stages of decomposition, but forensic scientists should use caution in applying nonhuman data to human bodies.
Date Published
November 12, 2018

When police find a body that has been hidden under a pile of leaves, left in a field, or dumped in a remote wooded area, they typically turn to experts who understand the stages of decomposition in order to determine when the person died. For the non-expert, the study of the decomposition of a human body can be a grim process, but researchers at the University of Tennessee Forensic Anthropology Center note that accurately understanding the science behind "insect succession and development" in a decaying body is the foundation of forensic entomology. The research also furthers the understanding of forensic taphonomy, the study of postmortem changes of a body.

The researchers, in a project supported by the National Institute of Justice, said that although the science of human decomposition is built on research done on dogs, pigs, and a wide range of other animal species, a problem may arise, "when data derived from animal studies are applied to explain decomposition phenomena in forensic casework of human remains, particularly the postmortem interval [time since death]." Their research "informs an ongoing important debate about the applicability of nonhuman animal models in forensic research and its probative value in casework," they said.

The project compared decomposition processes in the bodies of five humans, five domestic pigs, and five domestic rabbits in each of three separate seasonal trials that cover spring, summer, and winter. The bodies were left out in nature at the Anthropology Research Facility at the University of Tennessee, a 2 acre facility designed for the systematic study of human decomposition to understand how the human body interacts with the environment after death. Researchers meticulously studied progression of decomposition and recorded their observations twice daily for each set of remains.

The researchers found differences in the patterns of insect activity on the bodies and in the preference in body types by scavengers, primarily raccoons. The data showed that among scavengers, there is "a preference for humans over the other species."

The results of the study, the researchers said, "clearly demonstrate differential decomposition among humans and nonhuman animals." Rabbits do not make a suitable proxy for humans, they said, and while pigs are a closer proxy, there are still significant differences. "In sum," the researchers wrote, "our data indicates that human data is best for determining human patterns of decomposition in forensic cases."

About This Article

The research described in this article was funded by NIJ award 2013-DN-BX-K037, awarded to the Forensic Anthropology Center, The University of Tennessee, Knoxville. This article is based on the grantee report "A Multidisciplinary Validation Study of Nonhuman Animal Models for Forensic Decomposition Research" (pdf, 30 pages) by Dawnie Wolfe Steadman, Director of the Forensic Anthropology Center, The University of Tennessee.

Date Published: November 12, 2018