Death
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For other uses, see Death (disambiguation).
"Dead" redirects here. For other uses, see Dead (disambiguation).
"Deceased" redirects here. For the death metal band, see Deceased (band).
A dead soldier in Petersburg, Virginia 1865 during the American Civil War
A dead soldier in Petersburg, Virginia 1865 during the American Civil War
The tombstone of William Rogers, died March 11, 1873.
The tombstone of William Rogers, died March 11, 1873.

Death is the cessation of the biological functions that define living organisms. Numerous factors can cause death: predation, disease, habitat destruction, senescence, conflict, malnutrition, for example, or mere accidents resulting in terminal physical injury. Principal cause of death in people in developed countries is disease precipitated by aging. The chief concern of medicine has been to postpone and avert death. Precise medical definition of death, however, becomes more problematical, paradoxically, as scientific knowledge and technology advance.
Contents
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* 1 Biology
o 1.1 Fate of dead organisms
o 1.2 Competition, natural selection and extinction
+ 1.2.1 Extinction
o 1.3 Evolution of aging
* 2 In medicine
o 2.1 Definition
+ 2.1.1 Misdiagnosed death
o 2.2 The Legalities of Death
o 2.3 Causes of human death
+ 2.3.1 Signs
+ 2.3.2 Autopsy
o 2.4 Life extension
* 3 Death in culture
* 4 See also
* 5 References
o 5.1 Additional references
* 6 External links

[edit] Biology

[edit] Fate of dead organisms

In animals, small movements of the limbs (for example twitching legs or wings) known as a postmortem spasm can sometimes be observed following death. Pallor mortis is a postmortem paleness which accompanies death due to a lack of capillary circulation throughout the body. Algor mortis describes the predictable decline in body temperature until ambient temperature is reached. Within a few hours of death rigor mortis is observed with a chemical change in the muscles, causing the limbs of the corpse to become stiff (Latin rigor) and difficult to move or manipulate. Assuming mild temperatures, full rigor occurs at about 12 hours, eventually subsiding to relaxation at about 36 hours; however, decomposition is not always a slow process. Fire, for example, is the primary mode of decomposition in most grassland ecosystems.[1]

Some organisms have hard parts such as shells or bones which may fossilize before decomposition can occur. Fossils are the mineralized or otherwise preserved remains or traces (such as footprints) of animals, plants, and other organisms. Fossils vary in size from microscopic, such as single cells, to gigantic, such as dinosaurs. A fossil normally preserves only a small portion of the deceased organism, usually that portion that was partially mineralized during life, such as the bones and teeth of vertebrates, or the chitinous exoskeletons of invertebrates. Preservation of soft tissues, such as in mummification, is extremely rare in the fossil record.

[edit] Competition, natural selection and extinction

Main articles: Competition (biology), natural selection, and extinction

Death is an important part of the process of natural selection. Organisms that are less adapted to their current environment than others are more likely to die having produced fewer offspring, reducing their contribution to the gene pool of succeeding generations. Weaker genes are thus eventually bred out of a population, leading to processes such as speciation and extinction. It should be noted however that reproduction plays an equally important role in determining survival, for example an organism that dies young but leaves many offspring will have a much greater Darwinian fitness than a long-lived organism which leaves only one.

[edit] Extinction
The Dodo, shown here in illustration, is an often-cited example of modern extinction.
The Dodo, shown here