What causes the distinctive odor of decomposition?

There are hundreds of chemicals released by decomposition, with the smelly ones being mostly volatile oils. The sheer number and variety of chemicals is why it’s difficult to give an absolute answer in forensics to whether or not there has been a corpse present, as was seen most recently in the Caylee Anthony case. So it’s no one thing which produces the smell, but a vast number and variety of things.

@SmashTheState Ah.. hence the “Volatile Fatty Acid” evidence I’ve read about pertaining to the Anthony case. Tsk tsk, its a shame the jury wasn’t educated enough about the odor. Did they really think it was just a trash bag with some old food in the back?

@whitetigress A bag of rotting trash will release a lot of the same chemicals as a decomposing human body. Not all the same, but enough that it’s possible to get a false positive from the tests used in forensics, which involve only a handful of the hundreds of chemicals released on decomposition.

@SmashTheState Isn’t the fatty acid within a human distinguishable amongst other animals?

@whitetigress How do you differentiate between the chemicals given off by a human corpse and the chemicals given off by the meat in a rotting hamburger? The differences are very small, and there are two separate problems: (1) they can’t test for every single one of the hundreds of different chemicals, and (2) the tests they use have technical limitations, where they can sometimes react with common artificial chemicals (such as the cleaning chemicals used in car fabrics) to give false positives.

Cadaver dogs are more reliable than chemical tests (because their noses are capable of picking up hundreds of chemicals at concentrations much smaller than we can currently detect mechanically), but you can’t interview a dog. We don’t know if they’re excited because they detected the corpses they were trained to identify, or because they picked up the scent of a bitch in heat.

I have smelled dead deer, dead rabbit, dead dog and dead cow. I have also smelled rotten raw meat, and at one point smelled a decomposed raw turkey after it was kept in a non-working chest freezer for 6 months, and have to say that they all smelled the same to me. It is a very distinctive smell and there is no mistaking it. No amount of garbage or spoiled food smells like that.

@SmashTheState So what causes the smell?

Stiff is a good read and judging by this and your other question this evening, might be of interest to you. I think it answers this and the other question to some extent.

@SuperMouse I’ll put it in my Christmas Wish list! I love the title.

Here:

http://www.deathreference.com/Py-Se/Rigor-Mortis-and-Other-Postmortem-Changes.html

and also, page 3 (1.3, Stages of decomposition of a body) here: http://xa.yimg.com/kq/groups/16654743/2075882911/name/Forensic%252Bentomology.pdf