They have invaded the movies, games, music, and even literature of American culture. The first depiction of the flesh-eating undead we have all grown to know and love started with George Romero’s famous black-and-white cinematic adventure Night of the living dead, which changed the thoughts of zombies being people with no control to a whole other type of creature. While coming back from the dead to consume the living may be a bit far-fetched, many zombie-like traits can be explained by science. One example of this would be a mutation of the rabies virus. Animals and people with rabies often display the symptoms of insomnia, confusion, paranoia, and hallucinations (Auerbach, 2009). The rabies virus can transfer through the transfer of bodily fluids from an infected individual to that of an uninfected one, most commonly: bites, which is also how the zombie virus is supposedly spread. Considering how densely populated urban areas are, if one person were to contract this hypothetical virus, the entire city could be infected in days.
Another form of zombies resides in brain parasites. Some parasites are able to influence our thoughts and even control us without us even knowing. One such example of this is Toxoplasma gondii, which is a brain parasite that resides in 50% of the people in the US but only psychologically effects rats (Hokelek, 2009). This parasite can only breed inside of the intestines of a cat, and therefore controls the rat to walk straight up to the cat to be consumed (Hawes, 2009).
Another instance of a parasite causing zombie-like behavior would be with Glyptapanteles, a type of parasitic wasp, lays about 80 eggs in young geometrid caterpillars. When the eggs hatch, the larvae feed on the caterpillar’s bodily fluids. When they are fully developed, they burst through the caterpillar’s skin and form a cocoon on a nearby leaf or branch. The caterpillar then stands arched over the cocoon without feeding or even moving away. This zombie caterpillar stays alive until the adult wasps hatch, upon which it promptly dies. These controlled caterpillars also respond differently to the environment than regular ones. Unparasited caterpillars barely notice when a stinkbug or other harmless animal comes near it or even crawls on it. The controlled caterpillars, however, thrash violently at the sign of danger to the larvae until the threat is gone. When dissected, it is revealed that one or two of the parasitoid larvae stay behind in the caterpillar and control it to protect the brood (Brahic, 1008).
Zombies are known for being able to come back from the dead, which may seem impossible, but is possible if the person is not entirely dead; the poison from Fugu, a Japanese blowfish, is able to do this. Datura Stramonium is a chemical that leaves the person in a trance-like state with no memory, but still able to perform simple tasks. One such recorded incident was of Clairvius Narcisse, a Haitian who was declared dead by two doctors and buried in 1962. He was found wandering around the village 18 years later. A local voodoo priest had been using these naturally occurring chemicals to zombify people and put them to work on the sugar plantations (Wood, 1987).
A zombie is driven entirely by the most basic emotions, such as rage, that are located in the amygdale, which is one of the most primitive parts of the human brain. Researchers have introduced abnormalities into the amygdale of animal specimens; this results in a drop in the attack and retreat response that directly correlates with the amount of damage that part of the brain receives. The area known as the anterior cingulated cortex modulates and controls the excitement of the amygdale as it talks to the frontal lobe, which controls the thought and problem solving processes. So if the cingulated cortex dysfunctions, it would cause the person to be unable to modulate the feeling of anger, which would result in hyper-aggression (Schlozman, 2009) This would cause them to attack others, much like a zombie, with a blind rage.
With all of this taken into consideration, the possibility of a zombie outbreak, or at least something similar, is very probable. Whether it be natural, drug induced, or psychological, the significance of so many possibilities having one general output would be considered frightening to most people.
Auerbach, P. (2009). Rabies virus, symptoms, vaccine, and treatment. Retrieved from Survive Outdoors website: http://www.surviveoutdoors.com/reference/rabies.asp
Hawes, D. (December 9, 2009). Parasites in the Brain. Retrieved from Psychology Today website: http://www.psychologytoday.com/blog/evolved-primate/200912/parasites-in-the-brain
Hokelek, M. (January 27, 2009). Toxoplasmosis. Retrieved from eMedicine website: http://emedicine.medscape.com/article/229969-overview
Wood, C. (1987). Zombies. Retrieved from American Chemical Society at: http://www.district87.org/staff/sutterm/Chem%20Matters/Organized%20according%20to%20topics/Misc/Zombies.pdf
Schlozman, S. (2009, June 10). A Harvard psychiatrist explains zombie neurology. Retrieved from http://io9.com/5286145/a-harvard-psychiatrist-explains-zombie-neurobiology
Brahic, C. (June 04, 2008). Zombie caterpillars controlled by voodoo wasps. Retrieved from http://www.newscientist.com/article/dn14053-zombie-caterpillars-controlled-by-voodoo-wasps.html