Bones & Forensic Anthropology

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Decomposition - Wikipedia, the free encyclopedia

Decomposition (or rotting) is the process by which organic substances are broken down into simpler forms of matter. The process is essential for recycling the finite matter that occupies physical space in the biome. Bodies of living organisms begin to decompose shortly after death. Although no two organisms decompose in the same way, they all undergo the same sequential stages of decomposition. The science which studies decomposition is generally referred to as taphonomy from the Greek word τάφος taphos, meaning tomb.

One can differentiate abiotic from biotic decomposition (biodegradation). The former means "degradation of a substance by chemical or physical processes, e.g. hydrolysis.[1] The latter one means "the metabolic breakdown of materials into simpler components by living organisms",[2] typically by microorganisms.

Pig carcass in the different stages of decomposition: Fresh > Bloat > Active decay > Advanced decay > Dry remains

 

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How long does it take a dead body to decompose?

The decomposition of a dead body depends on many factors, any of which can affect the time necessary to break it down. If a body is buried in a coffin deep in the ground, for example, it could take as long as 50 years for all of the tissue to disappear. But if it is exposed to the elements, it will decay very quickly. The most important factor in decomposition time is how much exposure the body has had to bacteria. Bacteria need oxygen to survive and are generally found in heavy concentrations in water. Therefore, exposure to air or water will speed up the process of decomposition dramatically. Animals and insects will feed on the tissue if a body is exposed, also quickening the process. Regardless of how long it takes for tissue to be completely broken down, it may take the underlying bones hundreds of years to fully decay.

 

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http://www.memorialpages.co.uk/articles/decomposition.php

UPON DEATH
Nature is very efficient at breaking down human corpses. When you die your heart stops pumping blood around your body, thus depriving your cells of oxygen, which rapidly begin to die. Decomposing starts almost immediately, with the skin going through several changes in colour as the blood stops circulating leaving the body an ashen color. However different cells die at different rates. For example, brain cells die within a few minutes, whilst skin cells can survive over 24 hours after death. Soon after death rigor mortis occurs, which is caused by a complex chemical reaction (involving lactic acid and myosin), which forms a gel like substance which creates the body's stiffness. Rigor mortis lasts approximately 24 hours (depending upon ambient temperature).

Upon death blood also starts to settle in the those parts of the body that are closest to the ground, turning the top part grayish white and waxy looking, whilst darkening the underside. This results in a deep red-brown stain. For example if a person was to die and keel over head-first then the blood would settle in their head, which would result in a bruised-like stain to the face and neck. Body extremities will naturally turn blue within 8-12 hours without intervention (eg embalming).

STAGES OF DECAY
Initial decay (Known as 'autolysis') - externally the corpse looks okay, but internally the organs are breaking down.
Putrefaction - after approximately two-three days bacteria are active and the body is swollen with gases and accompanying odours.
Black Putrefaction - Skin starts to turn black and the corpse collapses as gases escape.
Fermentation - Very strong odours with some surface mould but the body has begun to dry out.
Dry Decay - The cadaver has for the most part dried out and the rate of decay has slowed considerably.

 

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Following death, the human body progresses through five basic stages of decomposition. The duration and degree of each stage is largely influenced by the environment (temperature, humidity, etc.), body mass, any wrappings or coverings of the body, and obviously scavenging or other post-mortem disturbances. Additionally, submerged or buried bodies will decompose much differently than bodies left on the ground.

 

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The Rate of Decay in a Corpse

The rate of decay within the human body after death is normally split into two distinct categories. These are:
Autolysis: A process of self-digestion where the body's enzymes contained within cells begin to go into a post death meltdown. The process can be speeded up by extreme heat and likewise slowed down by extreme cold.
Putrefaction: Bacteria that escape from the body's intestinal tract after the deceased has died are released into the body and begin the process of literally melting the body down.

If you are of a nervous disposition you may choose not to read on.

http://www.exploreforensics.co.uk/the-rate-of-decay-in-a-corpse.html

 

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Differential decomposition patterns of human
remains in variable environments of the Midwest

http://scholarcommons.usf.edu/cgi/viewcontent.cgi?article=2740&context=etd

 

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