Decomposition

From Free net encyclopedia

(Redirected from Decompose)
For spoilage of votes, see Electoral fraud.
For other senses of this word, see decomposition (disambiguation).
This article is in need of attention; please see the talk page.

Image:Rotting fruit.jpg Decomposition is a phenomenon common in the sciences of biology and chemistry. In biology, decomposition refers to the reduction of the body of a formerly living organism into simpler forms of matter. In chemistry it refers to the breaking down of a large molecule into smaller molecules or atoms and is referred to as chemical decomposition.

The body of a living organism begins to decompose shortly after death. Such decomposition can be simplified in two stages: In the first stage, it is limited to the production of vapors. In the second stage, fluidic materials form and the flesh or plant matter begins to decompose. The science which studies such decomposition generally is called taphonomy.

Historically, the progression of decomposition of a living organism has been described as taking place in four stages: fresh (autolysis), bloat (putrefaction), decay (putrefaction and carnivores) and dry (diagenesis).

Contents

[edit]

Constituent factors

The rate and the manner in which an animal body decomposes is strongly affected by a number of factors. In a roughly descending degree of importance, those factors include:

Generally an unembalmed adult body buried six feet deep in ordinary soil without a coffin normally takes ten to twelve years to decompose fully to a skeleton, given a temperate climate. A basic guide for the effect of environment on decomposition is given as Casper's Law (or Ratio). This states that when there is free access of air a body decomposes twice as rapidly than if immersed in water and eight times as rapidly than if buried in earth, a ratio of 1:2:8 for air, water and under pressure of earth respectively. The skeleton itself is not permanent; acids in soils can reduce it to unrecognisable components as well (this is one reason given for the lack of human remains found in the wreckage of the Titanic, even in parts of the ship considered inaccessible to scavengers). Freshly skeletonized bone is often called "green" bone and has a characteristic greasy feel. Under certain condition (normally cool, damp soil) bodies may undergo a process known as saponification and develop a waxy substance called adipocere, caused by the action of soil chemicals on the body's proteins and fats. The formation of adipocere slows decomposition by inhibiting the bacteria that cause putrefaction.

In extremely dry or cold conditions the normal process of decomposition is halted, by either lack of moisture or temperature controls on bacterial and enzymatic action, causing the body to be preserved as a mummy. Frozen mummies commonly restart the decomposition process when thawed whilst heat desiccated mummies remain so unless exposed to moisture.

The bodies of newborns who never ingested food are an important exception to the normal process of decomposition. They lack the internal microbial flora that generate much of decomposition and quite commonly mummify if kept in even moderately dry conditions.

[edit]

Decomposition process

Template:Signs of death Decomposition begins at the moment of death. At this stage it is caused by two factors: autolysis, the breaking down of tissues by the body's own internal chemicals and enzymes; and putrefaction, the breakdown of tissues by bacteria. These processes release gases that are the chief source of the characteristic odour of dead bodies. These gases swell the body.

Scavengers play an important role in decomposition. Insects and other animals are typically the next agent of decomposition, assuming the body is accessible to them. The most important insects that are typically involved in the process include the fleshflies (Sarcophagidae) and blowflies (Calliphoridae). The green-bottle fly seen in the summer is a blowfly. Larger scavengers, including coyotes, dogs, wolves, foxes, rats, and mice may eat a body if it is accessible to them. Some of these animals will also remove and scatter bones.

[edit]

Embalming

Embalming affects the process, slowing it somewhat, but does not forestall it indefinitely. Embalmers typically pay the greatest attention to the parts of the body seen by mourners, such as the face and hands. The chemicals that are used in embalming will repel most insects, and slow the process of bacterial putrefaction (the embalming fluid acts to "fix" cellular proteins which means that they cannot act as a nutrient source for bacteria and it also kills the bacteria themselves), but will not preserve a corpse indefinitely. In sufficiently dry environments, an embalmed body may end up mummified and it is not uncommon for bodies in dry vaults to remain preserved to a viewable extent after decades, such as the murdered civil rights activist Medgar Evers. Another case of this would be the body of Lenin, who was kept submerged in a special tank of fluid for decades, almost perfectly preservedTemplate:Fact. Bodies submerged in peat bogs may become naturally "embalmed", arresting decomposition and resulting in a preserved specimen known as a bog body.

The time for the reduction of an embalmed body to be reduced to a skeleton varies greatly. It is important to note that when a body is decomposed before preparation embalming treatment can still be achieved (the arterial system is slow to decay) although it will not restore a natural appearance without extensive cosmetic and reconstruction work and is largely used to control the foul odours associated with decomposition.

[edit]

Importance to forensics

Various sciences study the decomposition of bodies. These sciences fall under the general rubric of forensics, because the usual motive for study of the decomposition of human bodies is to determine the time and cause of death, for legal purposes:

  • Forensic pathology studies the clues to the cause of death found in the corpse as a medical phenomenon
  • Forensic entomology studies the insects and other vermin found in corpses; the sequence in which they appear, the kinds of insects, and where they are found in their life cycle are clues that can shed light on the time of death, the length of a corpse's exposure, and whether the corpse was moved.
  • Forensic anthropology is the branch of physical anthropology that studies skeletons and human remains, usually to seek clues as to the identity, race, and sex of their former owner.

The Body Farm, located at the University of Tennessee in Knoxville has a number of bodies laid out in various situations in a fenced in plot near the medical center. Scientists at the University study how the human body decays in various circumstances to gain a better understanding into decomposition.

Image:DecayingPeachSmall.gif Peter Greenaway's film A Zed and Two Noughts [1] has a sub plot which explores decomposition and is intercut with an escalating series of time-lapse sequences watching various plants and animals decomposing, culminating with the decomposition of the two main characters in the film.

[edit]

Books

[edit]

See also

cadaverinede:Verwesung fr:Décomposition it:Decomposizione (biologia) he:ריקבון גופה nl:Verrotting ja:腐敗 pt:Decomposição

Retrieved from "http://www.netipedia.com/index.php/Decomposition"