Theresa Milstein has a fascinating question for this week.
"If someone died and was buried in a shallow grave in New England (about an hour northwest of Boston) for nine years, would only a skeleton and clothing be left behind? Or would hair, skin or anything else be left?"
Boy, this was both interesting yet gruesome to research. There's too much to cover in one post, so I'll just highlight some major themes on this topic.
(Warning: I hope you have a strong stomach for what follows! Be thankful I'm NOT posting any pictures...bleah.)
Stages of decomposition: a human body will go through a few stages, including a fresh stage, followed by bloat, active decay, advanced decay, and dry/remains. (For photos of these stages on a pig carcass, click here.)
Each of these stages can be sped up (with heat, moisture/humidity, exposure) or slowed down tremendously (in an oxygen-free environment, like peat bogs, or with very cold temperatures, acidic soil, dry environments, or lack of exposure to animals/insects).
Bacteria, outside the body and naturally occurring within the body, cause disintegration of the corpse. Early in decay, this microbial proliferation in turn releases gases and horrific odors. It's called putrification and causes the bloat stage of decomposition.
If the body is well covered in clothing, this may slow down decomposition. Being inside a structure (coffin, house) may as well.
Animals and insects active in the decay process can be used to accurately identify the timing of death. Blowflies (and their eggs, larva, etc.) are classically used in this timing process of early decay.
Hair and fingernails, being organic, will also break down and disappear with normal decomposition, but as we've seen in Egyptian mummies and peat bog mummies, they can be preserved as well.
Clothing decomposes depending on its type and the environment. Cellulose-based fabrics (cotton, rayon, linen) will degrade rapidly in soil, but will degrade slowly if the soil is alkaline (high pH). Protein-based fibers (silk, wool) will degrade slowly in acidic (low pH) environments.
Petrochemical-based clothing (nylon, polyester) will degrade very slowly or not at all, as there are no methods of decomposition in the natural world (yes, those polyester 1970's suits will outlive all of us, many times over.)
Adipocere, also known as corpse, grave, or mortuary wax, is a waxy substance caused by the oxygen-free metabolism of body fat by bacteria. It can look like a shell of wax in the areas where bodily fat used to be. It can also be black, grey, yellow, white, or have the consistency of wax, be semi-soft, or found in more liquid forms. Adipocere formation can occur in a cold, airless environment, such as a sealed casket, wet mud, or at the bottom of a lake. The pictures are hard to stomach. Google at your own risk.
The answer to Theresa's questions?
In northwest Boston, the soil can be loamy or mucky (yes, muck is a technical soil term, and yes, I spent too much time on this website researching soil northwest of Boston). But unless the body was put into a bog, there ought to be enough air in the soil to prevent mummification.
As the summers can be warm, we'd expect a normal process of decay. Being in this soil, a shallowly buried corpse would easily decay without adipocere formation over the course of 9 years. There would be little left of the body except a skeleton. There would be no hair or skin left.
As for clothing, only traces of clothing that were petrochemical based, such as polyester, or artificial shoes or soles, may still exist, or metallic bits from the clothing.
Here are some sites I used for gathering info, if you'd like to brush up on your forensics of body decay:
UK Website with topics on forensic corpse evaluation
Hair and Fiber decomposition in archeology
Post-mortem fate of human remains
University of Tennessee Forensic Anthropology Center aka "The Body Farm"
Tollund Man (peat bog mummy)
It was so interesting, but I did lose my appetite for about 24 hours after researching this. Hope you all recover as well!