The scent of death: Researchers reveal the smells cadaver dogs are trained to sniff out

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It’s a pungent odour that might turn your stomach sour and send you running in the other direction, but for some scientists, the scent of death is a much sought after cocktail.

Death will eventually come for all living creatures, but decomposition is far more complicated, and the distinct smell of a human corpse differs from that of a bird, pig, or any other animal.

Though much is still to be learned about the true scent of death, a number of chemicals have been identified, from those that smell like paint thinner to the compound with a ‘disagreeable garlicky odour,’ a new Reactions video reveals.

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It’s a pungent odour that might turn your stomach sour and send you running in the other direction, but for some scientists, the scent of death is a much sought after cocktail. A stock image is pictured 

DEATH'S FRUITY STENCH  

Among the five esters that have been found to distinguish humans from pigs were propyl hexanate, a chemical used to recreate the smell of pineapples and blackberries.

3-methylbutyl pentanoate, which has a ripe apple odour, was also found in the samples along with 3-methylbutyl 2-methylbutyrate, which has a cherry and apple odour.

In particular, the researchers identified 3-methylbutyl 3-methylbutyrate, which also smells of apples, and butypl pentanoate which has an aroma of raspberries.

The researchers warn, however, their results were only conducted on small tissue samples rather than whole bodies.

Uncovering the chemical makeup behind the human cadaver smell could vastly improve the efforts of forensic scientists and cadaver dogs, and could one day even allow for drone-mounted electronic noses that sniff out dead bodies, according to the video from the American Chemical Society.

Decomposition begins when a person’s enzymes and microbiome begin to break down the body.

Bacteria, insects, animals, and other factors then join the process.

But, the environment in which the body lies can play a role in decomposition as well, and can alter ‘death’s aroma.’

A body submerged in a lake, for example, won’t smell the same as a body found in the desert or inside a cement block, the researchers explain.

A human corpse gives off hundreds of different chemicals, including the famous ‘dead body smell’ compounds – putrescine and cadaverine.

THE SUMMERY SMELL OF THE FRESHLY DEAD 

The research from the University of Leuven builds upon work presented at this year's British Science Festival.

This previous research found shown the same chemical that gives a newly-mown lawn its beguiling scent is also emitted by dead bodies.

Grassy-smelling hexanal is found in the mixture of gases released in the first few days after death, the British Science Festival in Bradford heard.

The smells of paint thinner and nail varnish remover are also found when bodies are relatively fresh.

A few days later, when the body starts to get bloated, indoles, chemicals more usually found in heady perfumes, can be detected. 

But, these aren’t always measured in the air around a corpse.

Sometimes, these don’t become volatile and instead remain trapped within the body.

The most commonly detected molecules include two aromatic hydrocarbons, toluene and p-xylene.

While the first of these is often associated with a paint thinner smell, the latter is known to have a sweet aroma.

Along with this, scientists frequently find diethyl disulphide, which the researchers describe as having a ‘disagreeable garlicky odour.’

And, a person’s lifelong diet can play a role as well.

If a person drank fluoridated water, for example, compounds such as trichlorofluromethane may be emitted after death.

Scientists are continually working to identify the ‘true scent’ of human death, but this remains a challenge due to the exorbitant amount of contributing factors and the data required to account for different environments and statistical certainty.

Cadaver dogs can locate human bodies in water, mud, rubble, and other difficult environments – but, it is not always possible to train them using real human samples, and many rely on decomposing pigs to sharpen their nose

But, doing so would be a huge advancement in forensic capabilities, and would make it far easier to accurately train cadaver dogs.

These dogs can locate human bodies in water, mud, rubble, and other difficult environments – but, it is not always possible to train them using real human samples, and many rely on decomposing pigs to sharpen their nose.

‘If scientists could figure out the chemical cocktail that makes up the scent of human corpses, trainers wouldn’t need to use proxies or even real human parts,’ the video explains.

‘They could just use the synthetic scent instead. 

'Not only would it be easier to train cadaver dogs, researchers could also build electronic noses that might also be deployed in disaster areas, say on a drone.’ 

 

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