The flesh eating animated corpses of the dead or recently dead have taken on the name “zombie” in Western culture. The stories actually originated from the Afro-Caribbean spiritualistic religion of Voodoo where people were sometimes reportedly controlled as laborers to a powerful sorcerer. The idea that bodies of the dead can be reanimated, if not exactly brought all the way back to life, is still one of the foundations of Voodoo. However, popular horror fiction loves the ideas of zombies as well. Ever since Romero's Night of the Living Dead was released in cinemas all over American in 1968, people have been fascinated with the idea of a body that was brought back to life without the higher reasoning skills of the human brain. Older legends and mythology of the Western world depicted flesh eaters as vampires or ghouls who while not necessarily were Einstein knew at least what was going on and tactics to get what they really wanted—flesh. Taking the reanimated corpses of Voodoo and adding these flesh eating attributes really created the zombie archetype of the modern age—a rotting corpse that walks around with a hunger for flesh or more particularly brains. However, the past several decades have seen an explosion in the already steady fan base of zombies. With this explosion are of course different takes on what a zombie actually is and how they act and respond to living humans. Intelligence is always an issue of concern that must be firmly established in anything featuring a zombie as even the stupid corpses can be scary in masses but smart ones are especially horrifying. The zombie intelligence scale really has developed its own range with this popularity explosion that goes from completely feeble minded to something resembling very closely to human level smarts. Either way, if you are faced with a hungry mob of zombies, run to safety before trying to assess their mental capacity.
Zombies are generally always created in groups or masses. The zombie “contagion” or disease as most people of the modern world like to think of it can spread between corpses and living people (who have to go through the process of dying first of course) almost instantaneously. Rarely does it take more than a few minutes of being dead from the virus or infection to reanimate the body into a ravenous eating machine, meaning that it spreads like wildfire—particularly in the first stages of a zombie epidemic. The idea that these creatures would develop a hive mentality is not necessarily as far fetched as some people like to assume. Since all the bodies are created by the same means (a virus or contagion of sorts), it even makes logical sense that they would act as a group. However, the actual definition of a hive mind makes this level of zombie intelligence rare in its true form. The idea of a “hive mind” comes from real life superorganisms (individual organisms that socially group together with a very structured division of labor to create a metaphorical “single organism”) such as ants or bees. The technical part comes in though when most of the individuals lose ALL sense of self to merely be a working part of the whole. Zombies would therefore act en masse (which they tend to do) under one idea and one goal—eat, eat, eat all day long. The easiest way to defeat a hive mind group is to find a way to make their ultimate goal impossible, or try to find out if there is a single delegating leader of the hive (like a queen bee) who instructs the thoughts and actions of the working members and take out that leader. If there does exist a leader like this, take it out. The hive mind is useless without it.
The idea that zombies retain only basic instincts (“need to feed” and simple thought to get at what they want) and perhaps a few memories is the most popular idea of zombie mental capacity. Almost all modern zombies fall under this category of intelligence. They may have a few scarce memories of their previous life—places they frequented (such as those in Dawn of the Dead grouping at the local mall) and occasionally people they used to know even though any feelings for the person that would have prevented them from attacking that loved one or eating their flesh while still alive are lost. The idea that instinct is the only mental capacity left to the zombie after infection and subsequent reanimation is a relatively simple concept. The thought is that the individual's “soul” or “essence” dies with the physical death of the body. Therefore, the only thing left is the primal brain without any higher reasoning skills, virtues, morals, or even an “ew” reflex that makes them not want to eat raw flesh straight off a living human's skeleton. This creates an interesting predicament for the non-zombie humans left after an outbreak as they may still have a connection with loved ones (family or friends) even though the loved one's body is running rampant through the area trying to attack innocent non-infected humans. The simple physical representation of someone that the uninfected used to care for is enough to make them at least pause and even stop when being attacked by zombies. However, what the uninfected must understand is that instinct with scarce memories (none of which can cause the zombie to stop attacking or stop eating any living human) do not hold the original soul of the person.
Instinct and Later Development
The idea of instinct followed by possibly later cognitive development is a rarity in zombie representation as the slow evolution to a creature of semi-human intelligence takes longer than most movies, books, video games, or any other form of entertainment allow the epidemic or mass infection to run rampant. However, Romero's Night of the Living Dead and the subsequent sequels such as Dawn of the Dead or Moody's Autumn look at the zombie infestation as something that will continue and may possibly never be fixed with no amazing rescue or magic cure. This long period of time allows the zombies to slowly develop rudimentary intelligence like a child—brain “regrowth” and “redevelopment” the longer they live in this reanimated state. The problem comes about when the remaining living humans try their best to quickly and efficiently kill reanimated corpses as soon as they change. Only a handful of zombies reach a level of intelligence that is even noticeable by the nearby living humans.
Having zombies that are mostly human-like in intelligence and behavior (ignoring the eating and pulling off the raw flesh from living humans aspect) is a recent development in the zombie population of entertainment media. Regular, brainless zombies are scary in very large groups but the next level (a new breed of zombie) with intelligence and the ability to think out problems so that they can figure a way to get a living human flesh that doesn't require slamming their already decomposing bodies against brick walls or even work around normal pathways that are blocked so that they can get to the humans through back ways or inadvertent routes is the ultimate fear factor.