What Death Really Smells Like, And How Your Brain Knows What to Do About It
Anyone who has had the unfortunate experience of finding a dead mouse in their attic or coming across a decomposing deer in the woods knows exactly what death smells like. Although it is a very distinct smell, it is one that is difficult to describe due to the almost 800 chemicals involved in the process.
It also turns out that our brains have likely evolved to recognize the smell of death and act accordingly, even if we’ve never encountered the smell before. Once it hits our noses, the death stench acts like a “necromone” that alerts us that something has died and that we need to do what is necessary to make sure that we aren’t next.
Read More: After Death, the Necrobiome Helps Drive the Circle of Life
What Does Death Smell Like?
A body goes through many physical and chemical processes post-death and each of these processes has its own distinct smell. The smells associated with death are attributed to the emission of volatile organic compounds (VOCs) and other compounds like cadaverine and putrescine.
Cadaverine and putrescine are the two compounds responsible for the most identifiable and pungent smells released after death. These compounds, which are not considered VOCs, are produced by the decay of amino acids. They are extremely stinky and are what give a dead body its “rotten” smell.
When it comes to vertebrates, the death process is commonly divided up into five stages: fresh, bloat, active decay, advanced decay, and skeletonized. Each of the separate processes have different VOCs and scents attributed to them.
A fresh body will slowly start to develop a smell as changes in the body’s bacteria begin to occur. This smell will be faint and is often said to resemble almonds, mothballs, and candle wax. The middle three stages — bloat, active, and advanced decay — are where the smell really starts to develop and alert passersby, with notes of garlic, gasoline, and even freshly cut grass.
How the Smell of Death Helps Us Survive
For over 420 million years, animals have been evolving their ability to detect and respond to smells as a means of survival. Newer research has specifically focused on whether humans have developed these skills as well — and it turns out we have.
Specifically, studies have shown that even the slightest hint of putrescine can trigger humans’ threat management responses subconsciously. When exposed to putrescine across multiple experiments, humans displayed a heightened sense of alertness, the activation of the fight-or-flight response, and elevated aggression towards those outside of their experiment group. After exposure, people also showed increased reaction time and an urgent impulse to walk quickly away from the unseen source of the smell.
These responses show that the human brain processes the smell of death as a warning signal and prepares our bodies to deal with the associated threat.
Is the Smell of Death Dangerous?
Beyond signaling that there may be an imminent threat, inhaling the smell of death is not dangerous. VOCs and compounds like putrescine are only toxic to humans in extremely large amounts and won’t cause any adverse reactions beyond a likely bout of nausea.
Understanding and identifying the smells of death have actually been quite advantageous for humans and our ancestors. Even Homo ergaster and Homo erectus knew the power of the smell of death, often locating their butcheries far from their settlements to keep safe from scavengers and predators.
In the modern era, the science behind the smell of death is still crucial to help train cadaver dogs who play a vital role in finding missing bodies for the police and post-disaster situations.
Read More: Worms Can Smell Death, and It Strangely Alters Their Fertility and Fitness
Article Sources
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