User:Bella LC/Corpse decomposition

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Decomposition is the process in which the organs and complex molecules of animal and human bodies break down into simple organic matter over time. In vertebrates, five stages of decomposition are typically recognized: fresh, bloat, active decay, advanced decay, and dry/skeletonized. Knowing the different stages of decomposition can help investigators in determining the Post Mortem Interval (PMI) (Pokines, Symes). The rate of decomposition of human remains can vary due to environmental factors and other factors (*CITE). Environmental factors include temperature, humidity, and the availability of oxygen (*CITE). Other factors include body size, clothing, and the cause of death (*CITE).

Temperature
The climate and and temperature in which a corpse decomposes can have great effect on the rate of decomposition (Pokines, Symes). Higher temperatures will speed up the rate of decomposition as it accelerates the physiological reactions in the body after death (Pokines, Symes). Cooler temperatures will slow the rate of decomposition (Pokines, Symes). Sunlight availability will also influence the temperature and as a result influence decomposition (Pokines, Symes). When there is more sunlight available this will facilitate decomposition whereas shaded areas can slow down decomposition (Pokines, Symes).

Humidity
The amount of moisture in the environment in which a corpse decomposes also has an effect on the rate of decomposition (Pokines, Symes). Humid environments will speed up the rate of decomposition and will influence adipocere formation (Pokines, Symes). In contrast, more arid environments will dry up faster but will overall decompose more slowly (Pokines, Symes).

Oxygen Availability
Whether the corpse is in an more anaerobic or aerobic environment will also influence the rate of decomposition (Haglund, Sorg). The more oxygen there is available the more rapid decomposition will take place (Miguel). This is because the microorganisms required for decomposition require oxygen to live and thus facilitate decomposition (Miguel). Lower oxygen levels will have the opposite effect (Miguel).

Burial
Burial retards the rate of decomposition, in part because even a few inches of soil covering the corpse will prevent blowflies from laying their eggs on the corpse. The depth of burial will influence the rate of decomposition as it will deter scavengers and insects (Haglund, Sorg). This will also lower the available oxygen and impede decomposition as it will limit the function of microorganisms (Miguel). The pH of the soil will also have an effect on the rate of decomposition as it influences the types of decomposers (Haslam). Moisture content of the soil all affect decay. Moisture in soil will also slow down decomposition as it facilitates anaerobic metabolism (Pokines, Symes).

Wet environments
Submersion in water typically slows decomposition. The rate of loss of heat is higher in water and the progression through algor mortis is therefore faster. Cool temperatures slow bacterial growth. Once bloat begins, the body will typically float to the surface and become exposed to flies. Scavengers in the water, which vary with the location, also contribute to decay. Factors affecting decomposition include water depth, temperature, tides, currents, seasons, dissolved oxygen, geology, acidity, salinity, sedimentation, and insect and scavenging activity. Human remains found in aquatic surroundings are often incomplete and poorly preserved, making investigating the circumstances of death much more difficult.

Body Size
Body size is an important factor that will also influence the rate of decomposition (Mann). A larger body mass and more fat will decompose more rapidly (Mann). This is because after death, fats will liquify accounting for a large portion of decomposition (Mann). People with a lower fat percentage will decompose more slowly (Mann). This includes smaller adults and especially children (Mann).

Clothing
Clothing and other types of coverings affects the rate of decomposition because it limits the body's exposure to external factors such as weathering and soil (Haglund, Sorg). It slow decomposition by delay scavenging by animals (Haglund, Sorg). However, insects activity would increase since the wrapping will harbor more heat and protection from the sun, providing an ideal environment for maggot growth which facilitate decomposition (Haglund, Sorg).

Cause of Death
The cause of death can also influence the rate of decomposition mainly by speeding it up (Smith). Fatal wounds like stab wounds or other lacerations on the body attract insects as it provides a good spot to oviposit and as a result could increase the rate of decomposition (Smith).

Experimental Analysis of Decomposition on Corpse Farms
Corpse farms are used to study the decay of the human body and to gain insight into how environmental and endogenous factors affect progression through the stages of decomposition. In summer, high temperatures can accelerate the stages of decomposition: heat encourages the breakdown of organic material, and bacteria also grow faster in a warm environment, accelerating bacterial digestion of tissue. However, natural mummification, normally thought of as a consequence of arid conditions, can occur if the remains are exposed to intense sunlight. In winter, not all bodies go through the bloat stage. Bacterial growth is much reduced at temperatures below 4 °C. Corpse farms are also used to study the interactions of insects with decaying bodies.