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5 Stages Of Human Decomposition

Updated: Apr 15

5 Stages Of Human Decomposition Graphic

Death is an inevitable part of life and with death comes decomposition. This may leave many people feeling uncomfortable, overwhelmed, and even repulsed. Yes, it is not a particularly pleasant topic of conversation, but it is a natural process. A process that is as natural as being born.

The stages of decomposition include: autolysis, bloating, active decay, advanced decay, and skeletonization. Understanding how and when these stages of human decomposition occur may shed light on some questions you may have.

The various stages of decomposition will be the final "function" your body performs and is quite interesting. Human decomposition begins approximately 4 minutes after death, and signs of the stages only become visible within certain time frames. The timeline of this process will vary depending on certain factors.

Stage 1: Self-Digestion or Autolysis

Occurs: 24-72 hours after death.

Self-digestion or autolysis is also known as the "fresh" stage and is the first in the decomposition process. Within the first few hours, the body shows no obvious outward signs of change.

First, the body temperature will cool (algor mortis) to match the ambient temperature of its surroundings.

Blood and oxygen flow cease, leaving blood to pool (livor mortis) in the lower extremities while the muscle tissues become rigid. This is the onset of rigor mortis and can last up to four days. During this stage, the cells lose their structural integrity and release cellular enzymes that break down surrounding soft tissues. Bacteria digest what remains in the small intestine.

The decomposing human body begins digestion of the internal organs with small fluid-filled blisters beginning to appear on internal organs and eventually the skin. Towards the end of this stage, insects such as blowflies will be drawn to the decomposing body and lay eggs in any open wounds or cavities, such as the nose or mouth.

Physical changes to the body: No outward signs are present during the early stages.

Stage 2: Bloating

Occurs: 3-5 days after death.

As bacteria grow and multiply, they produce:

  • Carbon dioxide

  • Methane

  • Nitrogen sulfide

These gases cause a pressure build-up within the decomposing body and force internal fluids to be expelled via body cavities such as the mouth, nose, or anus.

If the bloating has caused ruptures to the skin, the exposed flesh may hasten the decomposition process due to the increased attraction of flies, maggots, and insects, and their feeding on the body.

During this stage, the skin is especially vulnerable. The release of hydrolytic enzymes causes the top skin layer to become loose and may result in skin slippage.

The release of these gases and fluids results in a rather foul, putrid odor (like rotting meat with a fruity undertone) during this stage of decomposition.

The odor is a result of putrescine and cadaverine, which are the chemicals produced and excreted by a decomposing body. Cadaverine is said to have a rotting fish odor while putrescine is more pungent and believed to be toxic.

Physical changes to the body:

  • Blood decomposes in areas where it has pooled, leading to skin discoloration of a purple/pink color

  • The outer layer of the body skin shows a vein-like marble pattern.

  • The body can double in size due to bloating.

Stage 3: Active Decay

Occurs: 10-25 days after death.

The active decay stage of human decomposition displays the most significant loss of body mass. By this point, most soft tissues have been processed and only the more resilient matter, such as bone, tendons, cartilage, and ligaments, remain.

Insect activity is at its highest during active decay and scavengers will further account for the loss of most soft tissues. The skin and muscles will liquefy and the decomposition will expand into the surrounding environment.

Maggots leaving the body signal the end of the active decay stage.

Physical changes to the body:

  • Significant loss of body mass

  • Blackening of the skin

  • Possible adipocere (waxy substance coating the skin)

Stage 4: Advanced Decay

Occurs: 20-50 days after death.

By the fourth stage of decomposition, most soft tissue will have decomposed or be digested. This leaves just the bones, tendons, ligaments, cartilage, hair, teeth, and sticky by-products.

At this point of advanced decay, insects such as beetles will feed on the tougher material.

Physical changes to the body:

  • Skin that has remained takes on a dry leathery appearance

  • The majority of the human remains have blackened or discolored

Stage 5: Dry Remains or Skeletonization

Occurs: 3 weeks - several years.

The final of the decomposition stages is the dry remains or skeletonization stage. It is exactly what it sounds like - there is no longer any trace of soft tissue, internal organs, or skin. What remains is only bones and sometimes hair.

Physical changes to the body:

  • Bones lighten due to exposure to the elements

Factors That Impact Human Decomposition

The stages of human decomposition can be affected by varying factors. Certain conditions can hasten or hinder the rate at which a human body decomposes.

The timeline given above is an estimate based on years of scientific and biological research.

Forensic pathologists have to take certain external factors into account when determining a cause and time of death.

Environmental factors

  • Temperature: High temperatures will speed up the rate of decomposition, and cooler temperatures slow it down.

  • Humidity: Humid environments will accelerate the rate of decomposition and encourage the formation of adipocere. In drier, arid environments, the human remains will dry out faster but decompose at a slower rate.

  • Wet environment: Human decomposition in water differs from the typical process. If a body is submerged in water, the overall process of decomposition will be slower, while other aquatic factors may result in significant differences.

  • Soil: If a body has been buried in the soil, insects, and flies will have limited access. This combined with the lower exposure to oxygen makes for a slower decomposition process. The pH level of the soil may also be a significant factor here.

  • Oxygen: The microbial activity that takes place during decomposition thrives in an aerobic environment. An anaerobic environment will slow bacterial processes, delaying the overall rate at which a human body decomposes.

Other factors affecting human decomposition

  • Body size: A larger body with a higher fat content will decompose faster than a smaller body with lower fat content. This is due to the larger quantity of fat that liquefies during decomposition.

  • Trauma: If the body has experienced any kind of trauma, such as fatal wounds, decomposition happens faster. The loss of blood as well as the exposure of open wounds will attract insects earlier and hastens this process.

  • Clothing: A decomposing body that is fully clothed or covered in some kind of material will be protected from environmental elements, such as the weather or soil, which may slow down the process. However, the covering also provides an ideal environment for insect activity. Maggots may grow faster and facilitate the rate of organic decay.

How the Stages of Human Decomposition Affect the Environment

Just as the environment can impact the stages of human decomposition, so too can decomposition impact the surrounding area. If a body is decomposing in an outdoor environment, the ground, soil, or water will absorb the liquefied matter.

This can change the physical chemistry of soil for years after decomposition. During the first four stages of decomposition, the area will see an increase in insect and, sometimes, predatory activity.

If a body has begun decomposing in an indoor environment, the surrounding areas will be affected. Unlike in the outdoors, where nature recycles materials, indoor decomposition is more of a biohazard which will require professional cleanup and decontamination.

When a decomposing body has been left for an extended amount of time, the organic matter may cause permanent structural damage to a home.

What to Do if You Encounter a Decomposing Body

If you have the unfortunate experience of encountering a decomposing body, be sure to follow these steps:

  1. Notify authorities and wait for them to arrive

  2. Do not touch the body or surrounding areas

  3. Once the body has been removed, and the investigation is closed, call for post-death clean-up services if decomposition occurs inside a home.

Risks of exposure to human decomposition

Decomposing bodies harbor many biohazards and health risks. You could be exposed to diseases from bloodborne pathogens, mold, viruses, and toxic gases such as putrescine. For this reason, it is pertinent that the biohazard decontamination is done by professionals.

At Chore-ology we provide several biohazard and decontamination services. We also recognize the sensitive nature of such circumstances and remain professional, discreet, and understanding during these times.

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