Jonathan Hayes – Notes On Forensic Medicine: Smell

Jonathan Hayes (www.jonathanhayes.com) is a senior forensic pathologist in the New York City Medical Examiner’s Office, and author of PRECIOUS BLOOD (Harper 2007) and A HARD DEATH (Harper, 2009).

Notes on Forensic Medicine: Smell

by Jonathan Hayes MD.

My sense of smell is pretty acute, an extremely useful attribute in my food writing career but a double-edged sword in my career as a forensic pathologist. For example, it’s pretty easy for me to tell when a particular decedent has been drinking heavily, but I will admit that I had a pretty rough time with decomposition when I began in the business.

I should be more specific in my terms: decomposition is the natural breakdown of tissues after death. We divide decomposition into putrefaction (damp rot under the influence of bacteria), mummification (where the body shrinks as it dessicates in a dry environment) and adipocere formation (typically occurring in cool, damp places, like waterlogged coffins or bodies recovered from a lake, adipocere is a condition in which the body fat is chemically converted into a soapy material sometimes called “grave wax” – it’s an odd process, because the body decays, yet its form is preserved, almost “cast” in odd, cheesy-looking material.)

In the early stages after death, cellular metabolism slows as the internal systems begin to break down. Lack of oxygen in the tissues triggers an explosive growth of bacteria, which feed on the body’s proteins, carbohydrates and fats, producing gases that cause the body to smell and to swell. In 1885, the German physician Ludwig Brieger identified two nitrogenous compounds – putrescine and cadaverine – as the chemical basis of the smell of putrefaction; there are, in fact, a host of volatile compounds involved, including substances related to butyric acid. While together these chemicals may be characteristic of putrefaction, they’re encountered in other places, giving odor variously to bodily fluids, rancid butter, bad breath and stinky cheeses.

A body may release gases within hours after death, even without visible signs of decay. In cities, bodies are often found when a “neighbor complains of a foul odor”, a history so common it’s occasionally shortened to “NCFO”. More poetically, I’ve heard the smell of decomposition referred to as “the stench of loneliness”; those who have partners or family are usually discovered before their bodies rot.

It was in Boston that I encountered my first putrefied body. A resident in General Pathology at Boston University Medical Center, I spent a lot of time at forensic autopsies – the medical examiner’s office autopsy room was on the top floor of our building. My first winter there (thanks to indoor heating, bodies decompose all year round in temperate zones, too; the extreme dry heat means that we tend to see more mummification in winter than in summer), I wandered up to the autopsy room and opened the door to find them working on a very putrefied body.

A well-run mortuary doesn’t really smell; it is washed frequently and properly ventilated, and most bodies examined are fresh. But I’d never smelled anything like that putrefied body; it was an overwhelming odor, dense, wet, vile, almost shockingly sweet, like the vomit of a drunk; it seemed to coat the skin and settle into clothes. I felt nauseated, and stepped back outside the room, closed the door behind me and leaned against the wall, retching.

When I felt better, I went back into the autopsy room. The stench grew stronger as I approached the body and watched; a couple minutes later, I had to go back out and retch again. Then I went back in. I’m embarrassed to admit it took me a couple of years to get used to it. This makes me something of a lightweight: in NYC, each month we teach forensic pathology to large numbers of junior doctors, medical students, paramedics and EMT’s, and I’ve only rarely seen anyone have to leave the room.

The response to the odor, then, is very subjective; most people are surprised by their lack of an intense reaction the first time they see an autopsy. The context is important, of course – in an autopsy room, the surroundings are so clinical, and everyone is so matter-of-fact about the work that there isn’t much emotional space to abreact – the opening sequence of the TV show Quincy, where the cops are dropping like flies, is wholly fictitious.

My own intense response to the smell of putrefaction was fascinating to me. I’d never encountered it before; the closest I’d come was the smell of rotting grass in a compost pile back in my days on a country club grounds crew while I was in medical school. But humans are wired to find the smell repulsive for biological reasons – we know immediately when meat has gone bad, and we do not eat it. (An interesting contrast: I learned on a wildlife documentary that hyenas thrive on rotten carrion. Apparently, the digestive tract of the hyena is so robust that it can happily consume anthrax-infected flesh without problem – a superb evolutionary advantage, because that limits competition for their food. Indeed, the hyenas in the film weren’t just wolfing down the rotting flesh, they were rubbing themselves on it, rolling in it like cats with catnip.)

Occasionally I’ve heard medical examiners joke that the smell of decomposition is “the smell of job security”. With time, it’s got that I don’t mind the smell any more – I may still wince a little when I first encounter the body, particularly when it’s an exhumation, where the body has been sealed tight with its gases for years, decades even. But after the first couple of minutes, I barely notice the smell – the overwhelmed nose shuts down quickly. So, yes, I’m better about it now. But still a very long way from the hyena’s embrace of decay…

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The huge Indonesian corpse flower (titan arum) blooms once every six years, and attracts insects by releasing chemicals including putrescine and cadaverine. It’s a pretty spectacular trick: not only does the broad petal that wraps the pollen-bearing spadix have the ruddy maroon color of rotting flesh, the plant generates temperatures equivalent to the temperature of the human body, volatilizing its scent to attract even more insects.