When most people think of mummies, a strange mixture of ancient curses and toilet paper-wrapped Halloween costumes come to mind. It comes as no surprise that the concept of mummies is linked to the magical and superstitious- after all; it is pretty unbelievable to see intact bodies that are 2,000 years old. How could you not think of zombies or ghosts?
Like all mysteries, however, mummies actually have a scientific explanation.
Human bodies decay and break down by two major mechanisms: autolysis and putrefaction. Autolysis is essentially a self-destructive process during which enzymes that typically aid in digestion begin to digest the body itself. After this, putrefaction begins when bacteria from the body’s flora or the surrounding environment start to break down the organic matter for their own nutrition, leading to the decomposition of the corpse. The bacteria introduce additional enzymes that continue the liquefaction, and eventually, the body will attract flies and scavengers that can feed on the remains. In order to effectively preserve a body, these processes must be interrupted, or at least slowed significantly. There are several known factors that can do just that:
- Water content: The bacteria and enzymes need an environment with water; so drying the corpse is essential to its preservation. The drying out of the body is known as desiccation, and can happen naturally in extremely arid environments, like the hot sands of the deserts, or can be chemically induced, like with the Egyptian embalming process, where the bodies were covered natural drying agent named natron.
- Temperature: In extreme temperatures, especially cold, dry environments, bacteria are unable to survive. In addition, many enzymes denature, or unfold, in extreme environments, and can’t function properly. This slows the decay process down greatly, and can also occur naturally, leading to mummies such as the Iceman found in the Italian Alps. It is actually very similar to the way that your freezer helps you to preserve food!
- Organ Removal: Removing internal organs that contain a large population of bacteria prevent decay from the inside out. This was an important part of the preparation of Egyptian mummies, where most major organs were removed from the body and placed into sacred canopic jars.
- Chemical Interactions: Many different chemical interactions can contribute to the preservation of human tissue. Some of the most common include:
- Exposure to heavy metals ions, including copper and arsenic, can lead to the denaturation of the enzymes involved in autolysis, as the metal ions bind to the polypeptides.
- Lime, calcium oxide, reacts with water and raises the temperature to form calcium hydroxide. This reaction process dries out the body and raises the pH, which can limit the effectiveness of enzymatic activity.
- Resins can be also be used in mummification, as an antiseptic and as a barrier against rehydration when spread over the skin.
I hope you found this interesting, and good luck with those linens!
References:
Aufderheide, Arthur C. (university Of Minnesota, Duluth), A. (2011). Scientific Study of Mummies. Cambridge University Press.
Harris, T. (2018, March 08). How Mummies Work. Retrieved from https://science.howstuffworks.com/mummy.htm
