Stages of Human Decomposition

 Human decomposition refers to the processes which cause a human body’s internal organs, tissues, and bones to decay and turn into organic material over time. Every dead person will go through the 5 main stages of decomposition: the fresh stage, the bloat stage, active decay, advanced decay, and the skeletal stage. 

The fresh stage begins at the moment of death with the body still warm and in relatively good condition. While the body may not seem like it’s decomposing, some post-mortem indicators may start to take place, like the body becoming pale (pallor mortis), cold (algor mortis), and stiff (rigor mortis). Pallor mortis occurs within 15 to 20 minutes after death. As the blood stops moving through the body’s smallest blood vessels, the body becomes paler. This is not visible as quickly on people with darker skin compared to lighter skin. The rate at which the body temperature cools down to sync with the environmental temperature depends on a lot of factors, such as, the clothing on the body, the environment, and the body’s weight. Rigor mortis refers to the stiffening of body muscles caused by certain chemical changes. Muscles use ATP (adenosine triphosphate) to release from their contracted state, but after death, the body’s stores of ATP quickly run out and the muscles remain contracted until the muscle fiber starts to decompose. This is usually first seen in the small muscles of the face and jaw. Autolysis, a process where the breaking down of the body’s cells release enzymes that start digesting cells and tissues, may also start to occur. 

The bloat stage is where the first visible signs of decay take place, the biggest being the inflation of the abdomen caused by a build-up of various gases made by the enzymes that start digesting the cells during the first stage as they start to release foul-smelling gas. These signs are particularly visible around the tongue and eyes with the gases making them protrude. The skin may also take on a marbled look caused by the transmission of hemoglobin in the blood to other pigments. This is also the stage where the body starts to release pungent odors, like those of the cadaverine and putrescine gases. 

During active decay, the internal gases are released from the body and the inflated corpse deflates. While the tissues break down, the body will look wet and strong smells will be noticeable. These putrid gases will attract various types of insects and are caused by many compounds, for example, indole and skatole. Through a process called liquefaction, fluids will begin to drain from the body through orifices (openings through which something may pass, in this case, particularly the nose and mouth openings). The internal organs will typically decompose in a certain order that starts with the intestines and ends with either the prostate or the uterus. Hair will detach and the ruptured skin will gain a black discoloration. 

In advanced decay, most of the flesh will be stripped from the skeleton but some may remain in denser areas such as the abdomen. The body will have a ‘caved in’ appearance and a cheese-like smell caused by butyric acid may persist. Degradation-resistant tissues like hair and cartilage are spared up to now. 

The skeletal stage gives us the remains of the corpse and typically consists of bones, some dried skin and cartilage. At this point there is usually no smell of decay and decomposition will significantly slow down, taking years or decades for the skeletal remains to disintegrate into dust.

Sources: What Happens to Our Bodies After We Die? | Britannica, What Happens to a Body in a Coffin? [Decomposition Timeline] (afteryourtime.com), Decomposition Stages of Human Body - Forensics Digest, Evaluation of Postmortem Changes - StatPearls - NCBI Bookshelf (nih.gov), Average Cost of a Natural (Green) Burial: A Price Breakdown | Cake Blog (joincake.com)