The students knelt alongside the slumped form, seemingly untroubled by the acrid, syrupy tang of human decay which hung in the air. They remarked on the amount of decomposition that had become evident since their last visit, such as the sloughed skin and distended midsection. The insects which feasted upon the decommissioned man were of specific interest, prompting a number of photographs and note-jottings. After surveying the scene to their satisfaction, the students strolled across the glade to examine a considerably more decayed corpse in the trunk of an abandoned car. Their lack of alarm wasn't altogether surprising, for they were part of the organization responsible for dumping these corpses-- along with dozens more-- throughout the otherwise serene forest. They were forensic anthropology students from the University of Tennessee.
[Editor's note: What follows may be unsuitable for the squeamish, read on at your risk.]
Affectionately referred to as the Body Farm, the facility was founded in 1981 by Dr. Bill Bass, a professor of anthropology at the university. Before the Body Farm was established, information on human decay was astonishingly inadequate, leaving criminal investigators poorly equipped for determining abandoned bodies' time of death. On one occasion, Dr. Bass was asked to estimate the post-mortem interval of some human remains, and conventional methods indicated approximately one year given the moist flesh still clinging to the man's bones. When other evidence later revealed that the body had been occupying its coffin since the Civil War, a flummoxed Dr. Bass took it upon himself to finally fill the forensic gap.
In the intervening years, many anthropology students at the University of Tennessee have been engrossed by the decay research at the Body Farm. A continuum of corpses occupy the facility thanks to unclaimed remains from the medical center, and persons who have donated their bodies to science. Owing to these selfless subjects, the stagnating field of forensic anthropology was rapidly revitalized.
As the lifeless subjects are interred into the grisly forest hideaway, each is assigned an anonymous identification number. Some are situated to provide interesting decomposition vectors, while others are used to reconstruct specific circumstances for police investigations. At any given time, several dozen perished persons are scattered around the hillside within automobiles, cement vaults, suitcases, plastic bags, shallow graves, pools of water, or deposited directly upon the earth. Except when clothing is necessary for a particular study, cadavers are disrobed, and frequently certain factors such as fire and chemicals are introduced to measure their effects. Grad students and professors return periodically to check on the subjects' progress, with occasional visits from police officers or FBI agents undergoing training.
Technically decomposition begins about four minutes after death, when cells are deprived of their usual supply of nourishment. Absent these food molecules, digestive enzymes begin gnawing upon the cells themselves, a process called autolysis. Within a few hours the chemicals that allow muscle fibers to slide freely are metabolized, causing a temporary profound stiffness known as rigor mortis. The body pales in color as its blood pools at the lowermost portions.
With the human immune system permanently off-line, the digestive bacteria in the gut gain the upper hand, causing an upset in the uneasy intestinal alliance. These bacteria begin nibbling on the body itself. As the host's cells steadily self-destruct from autolysis, their membranes rupture, spilling the nutrient-rich cell filling into the tissues. The bacteria thrive in this river of food, and they soon establish decomposition franchises at every extremity.
By day four or so, the rigidity of rigor mortis has subsided, and the rapidly reproducing anaerobic bacteria have expelled enough gas that the skin takes on a green tinge. The sickly sweet smell of decay begins to saturate the air as bacterial byproducts such as putrescene and cadaverine become concentrated, and the abdomen, groin, and face begin to show noticeable swelling. Steadfast insects have thoroughly colonized the cadaver, with writhing mounds of maggots obscuring every orifice and a fog of flies swarming above. Maggot-hunting beetles and wasps may join the fray, adding another dimension of mortality; as well as another measurable milestone for the entomologists.
As the tenth day of decay approaches, the bacteria-induced bloating becomes pronounced. Sometimes this pressure is relieved via post-mortem flatulence, but occasionally an over-distended abdomen will rupture with a wet pop. Ants, moths, and mites begin to capitalize on the corpse cornucopia along with the other insects, while the single-celled citizens dutifully dissolve the internal organs. Soon the soil beneath the corpse is sodden with liberated liquids, while the skin-- unappetizing to most insects-- becomes mummified and draws in close to the bones. Natural soap buildup might also be present due to the interaction of bodily fats and acids, a process known as saponification.
Although factors such as predators, toxins, age, and injuries may cause variations from this predictable progression, most corpses in the wild are skeletonized or mummified according to the formula y = 1285/x, where x is the average temperature in Centigrade, and y is the total number of days. When the decomposing donors have completed their stint at the Farm, their bones are steam-cleaned and added to the University of Tennessee skeletal archives, ready to return to the aid of science at a moment's notice.
Owing to the information harvested from the Body Farm, in a feat that is sure to impress at parties, any forensic entomologist worth their salt can now determine time of death when presented with a reasonably fresh unembalmed corpse-- sometimes to within an hour. Using the results of numerous experiments, investigators have the data to properly adjust post-mortem interval estimates, taking into account conditions such as burying, embalming, and weather. One example of such variation was Dr. Bass' underestimated civil War remains, which were found to be contaminated with lead from the cast-iron casket. This effectively embalmed the body, making the meat unpalatable to tiny foragers.
It should be noted that forensic entomology is not limited to those insects that feast upon the deceased. For instance, certain insect species can be highly particular to a localized area, so an automobile's route can sometimes be traced by examining the bugs smashed on the grill. Parasites such as mosquitoes can also act as nature's little DNA collection kits by taking tiny, itchy blood samples from unsuspecting perpetrators. Investigators can then erect traps to collect bugs in an area, and extract the evidence in classic Jurassic Park style. Life finds a way.
While the prospect of having one's naked, lifeless husk flung into the woods lacks general appeal-- most people opting to decompose with dignity in the privacy of an overpriced crate-- there is nevertheless an ever-growing waiting list of enthusiastic, not-yet-deceased Body Farm volunteers. Dr. Bass himself has stated that his hatred of flies compels him to decline the opportunity to rot for the benefit of science; but for some people, the idea of wasting a perfectly good corpse is just too horrible to contemplate.