Introduction

    A zombie is a corpse that has been reanimated, giving it the semblance of life.  Zombies have become prevalent in popular horror entertainment, such as movies, television, and video games.  This is largely due to the influence of George A. Romero's movies, which include Night of the Living Dead [1], Dawn of the Dead, and Day of the Dead.  However, the zombie legend predates Romero's movies, and is believed to have originated in Haiti.  There, stories were told of Voodoo sorcerers who could raise the dead and then control them.

    In modern popular culture, zombies are usually not controlled by a sorcerer.  Rather, they are able to function independently.  They are usually violent, with goal of killing, and often eating, living humans [2]. 

Properties of Zombies

    There is a general consensus on several physical and behavioral properties of zombies.  In the majority of zombie depictions, they:

• 
  Resemble human corpses in various states of decay.  They often have open wounds, rotting flesh, and missing limbs.  However, some, like those at the beginning of Night of the Living dead (see right), can almost resemble living humans.
• Move slowly, often described as shambling.
• Have limited intelligence.  They lack the problem solving skills that they had while alive.  However, depictions of tool use (e.g., rocks, weapons) are not unheard of, and some zombies have even been depicted as having limited speech capabilities. 
  
• Travel and attack in groups.  What zombies lack in speed and intelligence, they make up for in numbers.  It could be argued that the tendency to gather in hoards is the defining property of modern zombies.[3]

This is a basic description of the common proprieties of a zombie. These can vary depending on what the depicted cause of the zombie outbreak is.

How to Kill a Zombie

    If ever attacked by a zombie, there is but one important thing to remember: aim for the head. An almost universal property of zombies is that one can only be killed by destroying its brain, or otherwise removing its brain from its body.  If a gun is available, shots to a zombie's body will be ineffective, but a shot to its head will often kill it instantly.  Beheading with sharp weapons is also effective.  Zombies have sometimes been depicted as being especially sensitive to fire as well, and fire can also prevent any dead people from returning as zombies.

Origins of Zombiehood and The Zombie Apocalypse

    A group of zombies is not usually depicted as an isolated incident, but rather a worldwide phenomena that can or does result in the end of civilization.  There are several reasons for the apocalyptic nature of zombie stories:

• The origin of zombies is often something that affects the entire planet.  It usually begins with all recently deceased people, worldwide, rising from the ground.  While the specific reason for the zombie outbreak is often unknown or unimportant, explanations have included radiation from space, viruses, alien influence, and chemical experiments.
• Becoming a zombie is contagious.  If a living human is bitten by a zombie but survives, they will often die some time later, only to be reanimated as a zombie soon after death.  Any human killed by a zombie will rise up as another zombie.  Thus, zombies grow in number exponentially, until no living humans are left.

Variations on the Zombie Mythos

    There are as many exceptions to the properties laid out above as there are depictions of zombies. However, one notable deviation from the standard zombie depiction occurred in the 2002 movie 28 Days Later.  Not only were the zombies not corpses (they were living humans infected with a virus), but they were able to run quickly.[4]  This seemingly minor change marked a major shift in the feel of the zombie movie.  This change was repeated in the 2004 remake of Dawn of the Dead.  Although fans of George A. Romero's seminal zombie movies were upset before the movie's release, it was generally well-received by both fans and critics.  Modern depictions of zombies may continue to include the ability to run.

Conclusions

    The rules and properties described here are by no means universal or complete. However, they describe the prototype of the modern zombie, as depicted in recent movies, television, and video games in the horror genre.  Do not take the information presented here as fact, and realize that, in the event of a real zombie outbreak, you're pretty much screwed.

Other Resources

• General Zombie Theory (on Knol)
• How zombies work (Howstuffworks.com)
• Survivors and Victims - Val Lewton's Film "I Walked With a Zombie" (on Knol)
  
• Wikipedia's long list of zombie films
• Zombie Surival and Defense Wiki