Decomposition and time of death data gathered from studies using dead pigs as stand-ins for humans do not produce accurate results, new research has found.
Pig cadavers do not provide
same accuracy as previously thought
Forensic investigators routinely rely on pig studies to pinpoint timelines when giving evidence in murder trials but the latest findings suggest that the information is not reliable enough to be used in court.
The study, conducted by researchers from the University of Tennessee’s Forensic Anthropology Centre – better known as the Body Farm – examined how 15 pigs, rabbits, and humans decomposed in the same environment. Three separate experiments were conducted, each involving five of each type of corpse being left outside during winter, summer, and spring.
The researchers found that all of the test subjects decomposed at vastly different rates – with pigs on average decomposing significantly faster than humans. They also found that the rate of decomposition in the human body varied more wildly from body to body than the rabbits or pigs did. Specific body decay times have not yet been released, but the information led the researchers to conclude that pigs – or any other animals – cannot be used to accurately predict a time of death in a human.
"What we’re saying is that to estimate the time since death for human forensic cases, our results indicate that human subjects are best, because the pigs and the rabbits do not capture the variation we saw in the humans," the Body Farm’s director, Dawnie Wolfe Steadman, told The New York Times
"All of us have various diets, our body composition varies widely, and it’s not just weight," Steadman added. "Individuals who have a lot of fat decompose faster than lean individuals."
The team also found that medical conditions at the time of death also played a part with bodies of those who were on chemotherapy drugs decomposing at a different rate from those that were not.
Though pigs might not be fit to accurately describe how humans decompose, they are still valuable to forensic researchers, because they allow them to study which types of insects and scavengers flock to decomposing flesh in different regions and at different times of year.
The study has yet to be peer reviewed but if the findings are replicated, it could have major implications for the judicial system in Britain where academics and forensic practitioners alike have long called for a body farm to be established in the UK. This would first require a change in the law as, under current regulations, bodies donated to science in the UK can be used by medical students and trainee surgeons but not by forensic scientists.
At present all studies into decomposition in the UK are carried out using animal cadavers. Pigs are most commonly used but researchers also make use of deer and rabbit cadavers.
At present there are just seven functioning facilities in the world – six of them in the US and one in Australia – where actual human bodies can be used.
The University of Tennessee Anthropological Research Facility on the outskirts of Knoxville, Tennessee is the oldest of these, having first opened its doors in 1981. Around 100 bodies are donated each year.