In the movie Ed Gein, the protagonist (one can’t really call Ed a “hero”) disgusts everyone else at the table of the family who’s invited him to dinner by explaining the phenomenon known as slippage, which is, basically, the flaking or sloughing off of skin from the cadaver as a result of the unimpeded activity of bacteria on the skin.
Scientists don't generally have the same sort of first-hand experience as Ed had, so, to investigate the rate of decomposition under various circumstances, they operate body farms in a number of states. On such farms, corpses are buried in different types of soil or half buried or left fully exposed to the elements so as to demonstrate the time that it takes for various states of decay to occur. Insect infestation of the corpse (known as the “colonization” of the body) is also studied (a field, should you or your children or grandchildren be interested in joining its ranks) which is known as forensic etomology.
According to the experts in this discipline, blowflies are the first to take an interest in the remains, arriving “within minutes of death.” Opportunists, these flies deposit their eggs in wounds and body orifices and cavities, including the dearly departed one’s eyes, nose, and mouth. Within three days, these eggs hatch into maggots, which feed upon the body’s banquet of “soft tissues.” Forensic etomologists use these insects as timepieces to determine the time of death, as “Forensic Etomology” points out:
Since each Calliphorid species has a characteristic temperature-dependent growth rate, the larvae can be regarded as a biological stopwatch that starts ticking shortly after the victim dies. Forensic entomologists learn to read this stopwatch by determining which insect species are present and how far they have progressed toward adulthood. With good records of ambient temperature, the post-mortem interval (time elapsed since death) can be calculated to within a few hours, even when death may have occurred 2-3 weeks previously.Moreover, although neither blowflies nor their maggoty offspring are likely to have graduated from the Harvard School of Medicine, they can also tell scientists a thing or two about wounds and toxicology and offer even detectives a clue or two about whether the body was ambulatory--hopefully not under its own power--after its demise:
In addition to post-mortem interval, fly larvae can also reveal other important information about a crime:
- Wounds--blow fly larvae cannot penetrate undamaged skin. An infestation inside the chest or abdomen would suggest the possibility of a bullet hole or a stab wound.
- Movement--Since local conditions (e.g. sun or shade, urban or rural) affect which species will colonize a corpse, it may be possible to determine whether or not a body has been moved since its death.
- Toxicology--drugs or toxins from a corpse may be detectable in fly larvae even after the body tissues are too decomposed for standard toxicological tests (“Forensic Etomology”).
As the body continues to decompose, it puts on a spread for other insects with different, if not more discerning palates: “As a body continues to decay, it goes through successive stages of decomposition. Each stage is associated with a distinctive type of insect fauna.”
The body bloats from the gases that build up inside it as a result of the bacteria that are feasting upon its “moribund tissues,” until the maggots, penetrating “body cavities. . . release the gas,” in three to five days, after which “maggots, flies, ants, and carrion beetles are abundant.” Once they have stripped most of the flesh from the bones, slippage is no longer a problem, as decay really sets in, and, although “the insect fauna becomes fewer in number but there is greater species diversity: carpet beetles, ants, skipper flies, and mites are common,” at least until the body dries and “becomes skeleton zed,” after which only “ants an mites” remain as tenants, residing in the bones for another two to three years.
Other factors, such as temperature, weather, humidity, and quicklime (if it happens to be present) speed or slow the rate of decay, but, in general, on the average, for those of you who are writing a horror story or a detective story, here’s a handy, of not dandy, timeline chronicling the stages (fresh, putrefaction, black putrefaction, butyric fermentation, and skeletonization) and time intervals of decay (“Decomposition“):
- Fresh: the body cools to room temperature, allowing bacteria to digest carbohydrates, proteins, and lipids. Insects are first attracted to the remains
(“Decomposition”). Within a few hours of death, rigor mortis sets in, lasting about four days (Bellows).(First few days after death) “Decomposition”).
- Putrefaction: the body turns green as bacteria break down hemoglobin. Gases expel urine, other liquids, and feces from the body, and the mouth, lips, and tongue swell (Decomposition”). The abdomen and groin also swell (Bellows). The veins marbleize, red streaks along the vessels being succeeded by green streaks as bacteria cause the blood to hemolyze (“Decomposition”). Slippage occurs, and “over several days the spongy brain will liquefy and leak from the ears and mouth, while blisters form on the skin which eventually evolve into large, peeling sheets. Often the skin from the hand will slough off in one piece, an effect known as gloving” (Bellows). The green color darkens to brown. (First 10 days after death) (“Decomposition”).
- Black putrefaction: if “post-mortem flatulence” isn’t sufficient to release the gases inside the cadaver, the body cavity ruptures, releasing pent-up gases, and the corpse darkens further. Insects colonize the corpse (Bellows). This stage ends when the bones become apparent. (10 to 20 days after death) (“Decomposition”).
- Butyric fermentation: the body mummifies, drying out and loses its odor as adipocerous, or “grave wax,” a cheesy substance forms on the body. Insect activity has disposed of the internal organs (“Decomposition”).
- Skeletalization: this final period of decomposition may last years (“Decomposition”).
Bellows, Allan. "The Remains of Doctor Bass." Damn Interesting 290102007 260042008 http://www.damninteresting.com/?p=924.
"Decomposition." Wikipedia. 2008. Wikipedia Foundation, Inc.. 26 Apr 2008.http://en.wikipedia.org/wiki/Decomposition
Meyer, John R.. "Forensic Entomology." General Entomology. 210012007. North Carolina State University. 26 Apr 2008 http://www.cals.ncsu.edu/course/ent425/text01/forensic.html.
“Everyday Horrors: Forensic Etomology and Putrefaction” is part of the series of “everyday horrors” that will be featured in Chillers and Thrillers: The Fiction of Fear. These “everyday horrors” continue, in many cases, to appear in horror fiction, literary, cinematographic, and otherwise.