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The Five Mysterious Stages of Decay: Do You Know the Unique Changes at Each Stage?
The process of corpse decomposition is a critical area of research when conducting criminal investigations or forensic identification. When an animal or human body begins to decompose, the associated changes can be divided into five main stages: the fresh stage, the expansion stage, the active decay stage, the advanced decay stage, and the drying/skeletal stage. These processes not only help determine the time of death, but also help investigators clarify the circumstances of the incident.
Understanding the different stages of body decomposition can help investigators determine the post-mortem interval (PMI).
Five stages of corruption
Fresh stage
At this stage, the carcass is usually intact and free of insect infestation. Over time, a corpse undergoes the following physiological changes: a drop in body temperature (cooling), stiffness in the limbs, and blood pooling at the lowest points of the body.
Expansion stage
When microorganisms in the body begin to break down tissue, gas is produced, causing the body to swell. This process is accompanied by the release of unpleasant-smelling chemicals such as putrescine and cadaverine.
Characteristics of the bloating stage include loosening of the skin layers, and the breakdown of tissue cells helping to form a dark, mushy fluid called "drainage fluid."
Active decay stage
During this stage, the tissue begins to liquefy and the skin may darken. Blowing flies lay their eggs in lacerations and other open areas. At this time, insect activity increases, and if special insect species appear, additional time references will be provided.
Highly decayed stage
At this stage, almost the entire body will change color and turn black, and tissue deterioration and liquefaction will be nearly complete. During this process, the decay process will release chemicals such as nitrogen and phosphorus, sometimes changing the chemical composition of the surrounding soil.
Dry/skeletal stage
As the expansion ends, the body's soft tissues collapse and eventually only the skeleton remains. This represents the final stage of decay and identification of susceptible pathogens will become more difficult.
Environmental factors affecting corruption
Temperature
Climate and ambient temperature have an important impact on the decay rate of corpses. Higher temperatures accelerate physiological reactions, leading to faster spoilage. During the summer, for example, a body may decompose to its bones within nine days.
Humidity
Humidity in the environment also affects the decay process. A moist environment usually accelerates decay, while a dry environment may cause the body to dry out more quickly and decompose relatively slowly.
Oxygen supply
Microbial activity requires oxygen, so the abundance of oxygen directly affects the rate of decay. In an oxygen-deprived environment, decay is significantly slowed down.
Burial and other factors
Burial slows the decay of a body and affects the chemistry of the surrounding soil. Clothing and other coverings can also affect the putrefaction process, and these factors deserve to be considered by investigators in their analyses.
Experimental analysis of decay research
Experts conduct experiments at corpse farms to understand the decomposition process of human corpses and the environmental and intrinsic factors that affect decay. They found that high temperatures in the summer accelerate the putrefaction process, while low temperatures in the winter slow down bacterial activity. These experiments also help analyze how insects interact with decaying corpses, which is important for forensic research.
It can be seen that the process of corpse decay is a wonderful phenomenon in nature, which makes us have to think: Can our understanding of death help us better understand the nature of life?
