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Did you ever think why bodies decompose after dying? Why is it that they don’t decompose when they are alive? Of course, we humans are no exception. That is how it works because that’s the design of nature.

In this article we are going to try and understand why bodies decompose after dying. To understand that, we need understand the very mechanism that is triggered after death.

So, what happens to our body when we die?

Death means that the heart stops beating. Once the heart stops pumping blood to all parts of the body, a shortage of oxygen occurs. Remember that it is our blood that is responsible for carrying oxygen to each and every part of our body.

Immediately after the heart stops beating, whatever oxygen remains at disposal is used up by the body tissues and cells. The part of the body that takes the first hit is the brain because it is the only organ in our body which uses a large volume of oxygen we take in. It usually takes 3-7 minutes for the brain to use up all the oxygen at its disposal.

We need to understand that brain any other body part that is located above the heart will no longer get blood supply because the heart that was responsible for pumping the blood up is no longer functional.

Blood will automatically start flowing down to low-lying areas of the body. As the blood starts retracting at lower parts of the body, certain parts of the body start taking a pale appearance. The other parts where the blood starts accumulating starts taking a darker appearance.

Once a human dies, a set of processes kick in. Oxygen scarcity and blood retraction are two of those processes, but several other things happen as per the following time line:

Within 1 hour after death: At the very moment of death, a process called primary flaccidity sets in. This is the process where the entire body relaxes.

Pupils dilate, tension in eyelids in lost, limbs and joints become flexible. Muscles lose tension, making skin saggy, which makes the major bones and joints starkly noticeable.

The blood starts draining downwards in a process called pallor mortis. This starts giving the pale appearance. The gravity comes to work and pulls the blood in the areas that are close to the ground. Those areas appear dark because of accumulated blood.

3 hours after death: Muscles start stiffening. This process is known as rigor mortis.

12 hours after death: This is when the rigor mortis reaches its peak, making it very difficult to maneuver the dead body. Toes and fingers appear unusually crooked at this point.

24 hours after death: The body loses all its internal heat. This is when the body becomes cold. However, depending on the atmospheric temperature as well as total fat content of the body, this complete loss of internal heat may take longer. This process of losing all internal heat is known as algor mortis.

36 hours after death: Muscles start losing stiffness.

72 hours after death: Body tissues become completely relaxed and rigor mortis ends. This is the state of secondary flaccidity.

Why does the body start losing temperature after death?

Body starts losing temperature after death because all cellular activities inside the body stop. As all activities stop, no heat is generated through chemical reactions.

The normal temperature of the body when a person is alive is 37 degrees Celsius. The temperature of the body starts dropping in linear progression right after death.

In the first hours after death, the body loses 2 degrees. Then 1 degree every one hour is lost until the ambient temperature and body temperature matches, thereby halting all heat transfer.

This drop in temperature creates the perfect condition under which bodies decompose after dying.

So, why do bodies decompose after dying?

Interior decomposition starts first

Body decomposition after death is a complex process. The decomposition starts from inside. After death, the immune system of the body simply collapses.

This means, the bacteria and other microbes that live inside our body get a free ticket to attack the body cells.

Also, the temperature of the body drops gradually, this provides a perfect condition for the internal microbes to do their dirty job.

You will be surprised to know that bacteria inside our body actually sit there and wait for us to drop dead.

When we are alive, the temperature inside the body along with the immune system prevent the bacteria and other microbes from eating us from inside.

These microbes don’t really do well in hot conditions and the temperature in the body is just hot enough to prevent them from acting nasty.

A simple example will be an infection. When we get infected, we get fever. This is one of the methods of used by our body as a defense mechanism.

High fever actually means that our body’s white blood cells are fighting hard against the microbes to throw them out. When the fever goes away, it simply means that our body has won the battle.

But we really think that the fever itself is a disease and take medicines to put down the temperature. This is not really good because that way we actually use a weapon other than our body’s own defensive mechanism to ward off the microbes.

This gives the microbes a chance to understand our weapons and adapt to them. That’s the reason why modern day microbes are becoming very resilient to medicines like antibiotics. Anyway, that’s a different story altogether.

So when we die, our body simply loses the war it has been fighting ever since our birth against these microbes that live inside our body. As we mentioned just a while ago, when we die, our body temperature drops, allowing the microbes inside our body to thrive well.

However, most of internal organs stay absolutely free of these microbes when we are alive. Almost all the bacteria and other microbes stay concentrated in our gut and in our intestines.

They do try to make their way out of those places when we are alive, but the immune system simply keeps them put and even prevents them from harming their place of residence.

After death however, as the immune system comes to a complete halt, the bacteria and microbes that are located right in the junction of our large intestine and small intestine start digesting the intestines.

They actually start consuming the cocktail of chemicals that are released from dead and damaged cells. From there, these microbes push forward into the capillaries of our lymph nodes and our digestive system.

From there, they gradually start spreading out starting with spleen and liver and then pancreas, and then to the heart and brain and lungs and everywhere.

External decomposition sets in later

As the internal decomposition starts happening, cells inside the body start breaking down. Pancreatic enzymes start digesting the internal organs, releasing a terrible smell. Body tissues start producing gasses like hydrogen sulfide and methane. A green liquid starts oozing out of the tissues.

Lungs push out liquid from nose and mouth. All these invite microbes outside the body. Even insects are invited to the party. The body’s surface turns into a farmland for microbes and insects. Insects lay eggs on the body that hatch into larvae (usually referred to a maggots) that start eating through the flesh and gradually move inside.

When the maggots are born, they will thrive on the oozing fluid and they grow old enough to start eating through the flesh and burrowing their way inside the body. This is the second stage of the larval life of the maggots.

At this stage, they use their unique body makeup to eat and breath simultaneously without a single break. This is possible because their breathing apparatus is located on the back side of their body.

As the maggots keep eating, they keep releasing enzymes which helps to turn the flesh of the corpse into an appetizing goo. This is what gives the rotting and melting look to a corpse after a few days of death.

The rate at which the body decomposition takes place after death depends on the environment in which the body is left. The fastest decomposition takes place in water.

Bodies left on open ground decompose slower while bodies buried underground decompose even slower. The depth at which the body is buried also defines the rate of decomposition.

Well, that explains why bodies decompose after dying. Actually, we as living beings and we as bacterial and microbial food are separated by a very thin line.

Sources: 1, 2, 3

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