Humans naturally wonder what happens after death. While we may not have the spiritual or metaphysical answers, we do know what happens to the body as it decomposes. Though most of us have a cursory understanding of decay, not everyone knows that there are actually eight stages of death. The body goes through these specific stages of decay as it makes its way from still-warm-to-the-touch to complete fossilization.
How long it takes for a dead body to become a skeleton and go through the entire process of decomposition varies depending on several factors. The temperature of the environment, the fat content of the body, and other details affect how quickly the body decomposes. Or, like the mysterious bog bodies, how quickly the body becomes preserved. In some rare cases, the body will become naturally mummified, which can be more bizarre than these eight stages.
Pallor mortis - meaning “paleness of death” - happens a few minutes after passing simply because the heart stops pumping. Basically, once the blood flow stops, gravity takes over and all of the blood pools to the lowest parts of the body. Once that happens, the skin pales. The only reason humans have that “healthy” look when alive is due to the presence of blood.
The pooling eventually reveals itself during the fourth stage of death, called livor mortis. Those who are already pale from a lack of melanin or suffer from anemia often reach pallor mortis faster than others.
Rate of Occurrence: 15 to 25 minutes post-mortem.
The “coldness of death” happens relatively quickly, since the heart is no longer pumping warm blood throughout the body. Without fresh, warm blood pumping through the veins, there’s nothing to stop the body from adjusting to the temperature of the area it's in.
Although it takes about an hour for a body to lose its “living” temperature, many things can affect it, such as clothing. All those layers certainly help insulate the body, but if those clothes are wet, then algor mortis kicks in faster. The amount of body fat also greatly contributes to algor mortis as well - the thinner the body, the faster its temperature drops. The body’s temperature starts to increase again once the sixth stage starts, or during decomposition.
Rate of Occurrence: roughly 1 hour post-mortem.
As we exercise, our bodies produce lactic acid to help prevent our muscles from getting damaged by strenuous activity. During the “stiffness of death,” the body produces a copious amount of lactic acid. However, without the intake of oxygen to counteract the lactic acid, all muscles stiffen to the point of rigidity.
Of course, the more muscle a body has, the faster and more intense the rigor mortis stage becomes. Rigor mortis starts to fade once the body enters the fifth stage of putrefaction.
Rate of Occurrence: 2 to 48 hours post-mortem.
Livor mortis is known as the “bluish color of death” that starts to happen right after the heart stops beating. Without an active circulatory system, all the blood pools to the lowest parts of the body. During livor mortis, the body starts getting blotchy, and around the six-hour mark, the blood still retains some fluidity. If one were to press on the skin, the skin would turn white.
However, once the body passes the 10-hour mark, the stains become permanent as the blood congeals, and pressing the skin does nothing to change its color. When the hemoglobin in the blood starts to break down in the final stages of livor mortis, the skin begins to appear "marbled." Other signs also appear, such as blood spots due to ruptured capillaries.
Rate of Occurrence: 20 minutes to 12 hours post-mortem.