Perhaps because they were easier to control and kill, zombies never acquired the cachet of their undead cousins, the vampires. This phenomenon extended to science: zombie research was considered a less glamorous field and consistently lagged behind vampire research in funding. Since development of the vaccine in 1911, the zombie threat has been greatly reduced. However, this should not make us complacent. Most experts believe that in today's world, a zombie outbreak is far more likely than a vampire outbreak.
The zombie virus comes from the same Mononegavirales family as the Human Vampiric Virus. The virus is propagated mainly through ticks of the family Ixodidae. The prevalence of these ticks in tropical climes is the main reason for the large number of outbreaks in those regions. The nature of the spread of zombie plagues generally depended on the place of origin. Most urban plagues were spread by aggressive rats that had been bitten by an infected tick. In the country, the tick would bite humans directly, or pass the virus through mice, raccoons and other animals.
As was the case with vampirism, humans infected with the virus would pass it from their saliva into the bloodstream of another through the bite.
Stages of the Disease
The stages of zombie transformation are the same that occur in vampires, with two major differences: in zombies, the onset of symptoms and transformation occurs much faster and has no relation to the cycles of day and night.
Infection. Symptoms of zombie infection appear quickly: within one or two hours, the victim will develop a headache, fever, chills and other flu-like symptoms. Zombie infections last about half as long as their vampiric counterparts, mostly between three and six hours, during which the vaccine is 100 percent effective.
Coma. Zombie comas are considerably more brief than vampiric comas. While physiological changes-slow pulse, shallow breathing-are similar, the coma lasts only between four and six hours. Only the very young and very old do not survive zombie comas. Zombies have been found as young as five years old and as old as 90. As with vampires, the vaccine is 50 percent effective when administered during Stage Two of the infection: the longer the victim has been in the coma, the less effective the vaccine.
Transformation. Zombies awaken from their comas in a catatonic state. They are unresponsive to most stimuli as they shuffle about, trying to locate their prey. Unlike vampires, there is no acclimation period; a zombie will begin hunting immediately upon transformation.
Because of their catatonic state, zombies have been unable to offer any personal testimony to augment scientific research. Therefore, all we know about zombies is based upon empirical evidence. A person infected with the zombie virus is transformed into a single-minded hunting machine, with all changes to bodily functions serving the zombie imperative: locate prey, capture prey and feed. Overall, the changes that take place in zombies are more limited than in vampires, and primarily affect the nervous system and the muscular/skeletal system.
This system has been of great interest to researchers, as zombie nervous tissue appears to have regenerative properties not found in humans.
1. brain: because so little of it is crucial to their survival, zombies can survive an enormous loss of brain tissue. Former FVZA zombie specialist Dr. Waxman Himmelburger tells of encountering a zombie who had lost over 3/4 of his head from a shotgun blast, with no apparent effect.
2. spine/nervous system: zombies have exhibited the ability to withstand significant trauma to their central nervous system. In a famous series of experiments conducted by FVZA scientists in 1972, zombies who had their spinal cords severed regained the ability to walk within 24 hours. Thus far, researchers have been unable to unlock the mechanism for this process of repair.
3. dopamine: the smell of living flesh triggers a large release of this adrenaline-like neurotransmitter into the zombie brain
"Follow your nose" might be the zombie motto. A zombie's powerful sense of smell compensates for the weakness of their other senses.
1. sight: due to degradation of their corneas, zombies suffer from severe myopia. In addition, they are colorblind.
2. hearing: zombies go deaf within a few weeks of transformation
3. smell: zombies have even more receptor cells than vampires. If the wind is right, zombies can smell humans from as far as several miles away.
As anybody who ever emptied his gun into an advancing zombie can tell you, zombies just don't bleed to death. Their circulatory adaptations allow them to survive wounds that would kill a human.
Blood: zombie blood is thick and black, hence the nickname, "zombie oil."
Heart: as with vampires, zombie blood is circulated by skeletal muscles rather than the heart.
Zombie core body temperature ranges between 65 and 75 degrees, making them slightly warmer than vampires. This is due to heat released by the various parasites living in zombie flesh, a phenomenon that causes zombies to emit steam in cool weather and phosporescence when in water.
Muscular/Skeletal System and Connective Tissue
Changes here are of good news-bad news variety. Yes, zombies are stiff-limbed and slow, yes they move along at a shuffle rather than a sprint. But they are also very powerful, with a vice-like grip and jaws that can bite through metal.
1. Muscles/Connective Tissue: zombie muscle fibers become concentrated and take on the consistency of nylon rope. Ligaments and tendons thicken.
2. Skeletal system: important modifications occur to the zombie jaw. Extra bone is deposited on the lower jaw to form an attachment point for larger chewing muscles. These adaptations enable zombies to bite through skull and bone and get at the pillars of their diet: brains and bone marrow,
3. Teeth: zombie teeth are not adapted to the powerful forces exerted on them by the jaw. Teeth crack and fall out, and the holes they leave behind leak sludge-like zombie blood. Eventually, all their teeth are gone, and a zombie is forced to chew with its exposed jawbones.
4. Hair: zombies who live long enough will lose all their hair.
5. Skin: decay sets in shortly after transformation. The skin turns leathery, then rots away.
Aging and Life Expectancy
The great irony of zombie life is that even as they voraciously feed, they too are being fed upon. A zombie's body is like a big petri dish serving host to everything from bacteria and fungi to maggots and ants. The resulting state of putrefication means, as terrifying as a zombie may be to the eye, it actually commits far worse offenses to the nose.
A long-held, common misconception is that zombies are immortal. In fact, the vast majority of zombies live less than one year. It is possible to determine a zombie's age based on their external appearance; specifically, their level of decomposition, also known as necrotic degradation.
Stage I: the skin is mottled and covered with open sores.
Stage II: the ears and nose are rotting away. Loss of fingers and toes.
Stage III: large areas of exposed skull and bone, loss of limbs. Much of the teeth are gone, and one or both eyes fall out.