Testing the Use of Pigs as Human Proxies in Decomposition Studies

Abstract

Pigs are a common human analogue in taphonomic study, yet data comparing the trajectory of decomposition between the two groups are lacking. This study compared decomposition rate and gross tissue change in 17 pigs and 22 human remains placed in the Forensic Investigation Research Station in western Colorado between 2012 and 2015. Accumulated degree days (ADD) were used to assess the number of thermal units required to reach a given total body score (TBS) (1) which was used as the measure of decomposition. A comparison of slopes in linear mixed effects model indicated that decomposition rates significantly differed between human donors and pig remains χ = 5.662, p = 0.017. Neither the pig nor the human trajectory compared well to the TBS model. Thus, (i) pigs are not an adequate proxy for human decomposition studies, and (ii) in the semiarid environment of western Colorado, there is a need to develop a regional decomposition model.

Measuring Desiccation Using Qualitative Changes: A Step Toward Determining Regional Decomposition Sequences

“…An emphasis was placed on an all human cohort because proxies do not yield data with resolution sufficient to develop or refine models appropriate for use within human cohorts. The difference in decomposition rates between human and animal proxies has been repeatedly demonstrated . Pigs are the most commonly used analog but have fur that occludes the gross observation of superficial tissue.…”

Why does the UK need a Human Taphonomy Facility?

“…It is dangerous to assume that results and experience gained from animal experiments can be applied to human bodies. The fact that differences in the decomposition process between human and pigs have been found (Connor et al, 2017, Dautartas et al, 2018, Knobel et al, 2018, should worry all forensic scientists, and indeed all those working in the criminal justice sector. These findings can only come from institutions that have the ability to compare human and animal decomposition, but is it important that further research occurs on this topic.…”

“…This is not to say that animal experiments should stop. Such work is important to develop ideas and to identify trends in taphonomy (Connor et al, 2017), and are invaluable for undergraduate projects. However, it is vital that students wishing to pursue a career in forensic science are exposed to the sensory experiences of human decomposition, something that can only be achieved at a HTF.…”

“…A 2012 study in Texas also found differences in scavenging between animal and donated human cadavers (Rippley et al, 2016;Knobel et al, 2018). These differences suggest that animal carcasses not suitable as analogues for human remains (Duatartas et al, 2018;Connor et al, 2017;Stokes et al, 2013;Knobel et al, 2018;Alapo, 2016).…”

“…It has highlighted the enormous amount of variability that exists between and among humans, and that the rate of decomposition is affected by a vast array of factors, including temperature, humidity, access by insects, cause of death, clothing, body size and fat content, local fauna, soil type and many more (Blau, 2017;Byard, 2017). Research at UTK and other HTFs has also demonstrated that the data generated is only applicable to the immediate environment, particularly for postmortem interval estimation (Forbes, 2017;Connor et al, 2017). As a result, there is an ongoing need to establish HTFs in other geographical and climatic regions across the world.…”