Making “Scents” of the Smell of Death

If you thought the stench from preserved pigs during the 9th grade pig dissection unit was overbearing, imagine taking a whiff of a rotting corpse. What exactly would it smell like? Scientists have pondered this disturbing question for decades, and although they have successfully compiled a list of organic compounds related to the decomposition process, their dilemma lies in discovering the ones solely released by humans. Recently, surprising news came from the University of Leuven in Belgium— researchers think they have finally pinpointed the exact chemicals emitted by human bodies.

The process

Analytical chemist Eva Cuypers, who led the experiment along with graduate student Elien Rosier, took samples from six autopsied humans and creatures such as pigs, frogs, and mice. The pig remains were particularly significant because they resemble human bodies in fat distribution, gut flora, and hair. All the samples were placed in jars with stoppered holes that allowed Rosier to periodically take samples of the gas building up inside.

Over the 6 month period, Rosier identified and compared the compounds in the collected gases. Her analysis revealed a whopping 452 organic compounds, but most were not present in or unique to humans. Ultimately, Rosier discovered that esters, also known as natural fats or essential oils, were the compounds that distinguished humans and pigs from the rest of the animal samples. Eight compounds distinguished pigs and humans from other animal samples,and a total of five esters were present exclusively in humans.

Looking ahead

The findings from Rosier’s experiment are important because “so far there [hasn’t been] any study based on monitoring human and pig carcasses under exactly the same conditions,” notes Agapios Agapiou, an analytical chemist at the University of Cyprus in Nicosia who was not involved with the experiment.

Despite the good news, Cuypers and her researchers have noted the shortcomings of their observations. The usefulness of the study could be potentially weakened by the fact that Rosier used individual organs rather than entire corpses, and the chance that chemical makeup is different for an entire body. And since the tissues were isolated in jars, researchers could only look at a branch of bacteria and couldn’t take into account all environmental factors that influence decomposition.

“The next step in our research is to see whether the same compounds are found in buried, full decomposing bodies in the field and to see whether dogs trained on the mixture respond more [specifically] to human decomposing bodies,” says Cuypers.

If all goes well, researchers will be able to train cadaver dogs to more accurately find human bodies and possibly even develop detection machines with the same abilities as the dogs in the near future.

But before that can happen, researchers are still tasked with finding whether or not whole bodies produce the same combination of esters when they decompose. ✦