From internet:
within a year all that is usually left is the skeleton and teeth, with traces of the tissues on them.
The intestines are packed with millions of micro-organisms that don't die with the person. These organisms start to break down the dead cells of the intestines, while some, especially bacteria called clostridia and coliforms, start to invade other parts of the body.
At the same time the body undergoes its own intrinsic breakdown under the action of enzymes and other chemicals which have been released by the dead cells. The pancreas, for example, is usually packed with digestive enzymes, and so rapidly digests itself
The decomposing tissues release green substances and gas, which make the skin green/blue and blistered, starting on the abdomen. The front of the body swells, the tongue may protrude, and fluid from the lungs oozes out of the mouth and nostrils.
This unpleasant sight is added to by a terrible smell as gases such as hydrogen sulphide (rotten egg smell), methane and traces of mercaptans are released. This stage is reached in temperate countries after about four to six days, much faster in the tropics and slower in cold or dry conditions.
A corpse left above ground is then rapidly broken down by insects and animals, including bluebottles and carrion fly maggots, followed by beetles, ants and wasps.
In the tropics, a corpse can become a moving mass of maggots within 24 hours.
If there are no animals to destroy the body, hair, nails and teeth become detached within a few weeks, and after a month or so the tissues become liquefied and the main body cavities burst open.
Edited by nikolai_gogol - 13 years ago