A Zombie is any form of mutated human, which displays certain characteristics, such as cannibalism, corpse-like appearance and apparent hive-mind mentality. They are the main combatant against the forces of humanity in the Human-Zombie War.
On the 1st of October, 1968, NIGHT OF THE LIVING DEAD was released in theaters. Three days later, a private group of scientists met and decided that if the symptoms of the virus could be recreated, then the destruction it could yield would be akin to the aftermath of a nuclear exchange. They reasoned that the virus could be controlled, and maybe even directed, to give them the ability to control an army of the living dead. Thus began their research, which initiated with the use of several common viruses, and blending their traits for the highest infectivity, and best re-creation of symptoms.
By December, they had created a highly unstable, yet promising prototype virus that contained most of the desired symptoms they sought. Unfortunately for the scientists, they underestimated the infectivity of the new virus, and all scientists were contaminated with the Virus by mid-January. Trips form their base of operations in Arizona to nearby towns inadvertently spread the virus. In its unstable state, the virus rarely infected the hosts it spread to; rather, they became carriers, and few suffered any ill effects. It was this same instability, however, that enabled the virus to begin evolving on its own, increasing the infectivity, incubation rate, severity of symptoms, and the robustness of the virus.
By the end of the month, people with strange symptoms began showing up in Arizona. By March 3, the symptoms began appearing all over the American Southwest. On January third, running out of funds, the scientist team made a trip to secure a deal with a private arms dealer in Milan, Italy. Though failing to secure a deal, the Arms company retained a (presumably weakened) sample of the prototype virus. Little did they know, they had come in contact with the most potent form of the virus carried by the scientist team.
During this time, strange deaths began occurring in secluded parts of Arizona. Still lacking funds, one scientist from the group travels to London to meet a potential buyer. The United States government arrests the remaining scientists five days later, and the scientists are transferred to Marine Corps Air Station Yuma to await a trial for charges of Terrorism, Treason and Murder. On the 1st of April, the first Zombie sighting occurred in Arizona. Though the US government attempted to aid major cities and stem the rising tide of Zombies, they were quickly overrun by the living dead. By the third of April, Marine Corps Air Station Yuma was overrun from the inside. By the end of the month, thousands of Zombies formed around the three principal Infection sites of Milan, London and Arizona.
Biological Aspects of Zombies
Once the Zombie Virus has fully incubated, and a person has become a Zombie, they lose all sense of self awareness, and revert to primal instincts, primarily the need to feed. Zombies generally feed on humans, though they will eat any living creature if nothing is available. Why they prefer humans is unknown. Most of their behavioral actions are also not understood. They are known to hunt in packs, but it is unknown why they do so, how they communicate, or if there is a hierarchy in the "horde."
The virus is known to initially affect the brain, and once infected, the brain shuts off most of the body's organs and functions, including all processes of the skin, most of the cerebrum, hormonal glands such as the liver, pancreas and gall bladder, the immune system, and in some cases, excretory functions such as the kidneys and bowels. Particles in their blood increase exponentially, and heart rate slows, causing their blood to act more as a thick syrup. As time goes on, more organs begin to fail, and eventually, a major organ, such as the heart or lungs will cease to function properly, and the Zombie will die, though the average natural lifespan of a Zombie is unknown.
Zombies can be divided into two main categories; Alphas and Betas. An Alpha, Type-A, or Primary Zombie is any Zombie whose transformation results from an airborne contagion. These Zombies are usually more intelligent, stronger and are able to retain organ functions for a longer period of time. These Zombies were once the most common during the early stages of the infection. However, most Zombies became betas due to Zombie bites becoming an easier method of infecting hosts.
A Beta, Type-B or Secondary Zombie is any Zombie whose transformation has occurred due to a bite, or contact with a Zombie. Type-B Zombies usually have higher levels of hormones such as adrenaline and testosterone. Type-B Zombies are more aggressive than Type-A Zombies, and are relatively faster. Type-B's are also less social, and are commonly seen fighting other Zombies. When hungry, will eat other Zombies, or even themselves.
To compare the two directly, Type-A's use strength and intelligence, while Type-B's use speed. Type-A's can infect others by bites, or through contact (including catching the contagion via the air by being near a Zombie), while Type-B's can only infect through bites. Occasionally, a person will become infected, and experience some symptoms of the early stages of the virus, but never progress to Zombie-ism. This person is designated as a Type-C or Carrier. There are very few persons that are carriers, and most are killed at the first signs of infection. Carriers almost always have a Type-A infection, so virtually all of those infected are in quarantine; though they have been useful to scientists seeking a cure.