Preface - The following is a compilation of the ideas of myself and others on a plausible but unlikely scenario known as the "Zombie Apocalypse". I do not own any of the works cited in this article, and will give credit to their creators. Most of this is based off of my knowledge and a little research, so if I have any details wrong in this article, or have left something out, feel free to comment and let me know.
If you live in the 21st century, you're probably pretty familiar with the idea of zombies. Zombies used to be human beings, but are now reanimated corpses, using only the most basic survival instincts in the human brain to survive and multiply. Destroying all living things in their path, a zombie's only thought is its next meal. In American mythology, there are many characteristics of zombies that differ between stories. These include different types of transmission, movement, responses to stimuli, senses, physical strength, and appearance. The worst part of all these discrepancies is that many of them are plausible in the event of zombie apocalypse. In part 1 of Zombie Warfare, I'm going to be taking you through all popular zombie mythology and explaining why some scenarios are more plausible than others, ultimately making what would be the most likely zombie to come lurching out of a hospital sick bay. This zombie will be what we prepare our defenses against in Zombie Warfare part 2, coming soon to Improvised Blog Title.
The Zombie Apocalypse starts with the disease. Nearly all zombie mythology agrees that a pathogen, parasite, or invasive fungus is the most likely to create a zombie. Most also agree that, whatever this invasive organism is, it works by shutting down all parts of the brain but those controlling basic survival instincts. This results in an animal with no fear, no compassion, and with only one motivation; to eat. If zombie apocalypse is to occur, it would be better to know what makes zombies, for the possibility of a cure.
- Virus -
Viruses are a commonly cited cause for zombification. However, that scenario is actually less likely than most think The biggest reason I can think of viruses are implausible is that they have surface proteins that target specific types of cells. If those cells are brain cells, they would continue to reproduce using the brain cells, and would not destroy a part of the brain, but the entire brain. Instead of a zombie, you would end up with a corpse (which would actually be preferable for the survival of the human race).
- Bacteria -
Bacteria are not specifically cited very often, but they are more likely than viruses for a couple of reasons. First, is that they reproduce independently of host cells through binary fission, so they do not necessarily need to destroy all of one type of cell. Another is that they are capable of independent locomotion. It's very limited, but it gives the bacteria a chance to move about the body, so they're not as localized. However, the bacteria is a living thing (whereas the virus is not), and it needs to eat. I suppose it would be possible for a bacteria to first infect the brain, and then travel through the bloodstream to the digestive organs and feed, but that would require a very advanced bacteria. What would be more likely is that the bacteria multiplies until it runs out of food, and then dies, leaving the zombie to walk around. However, this would limit the time frame necessary to transmit the living bacteria, and a month-old zombie would probably not be able to infect anyone new.
- Parasite -
This is also a likely cause. Now I don't know much about parasites, so most of what what's in here is going to be speculation. I figure that a parasite could disable the brain in an attempt to suppress resistance against the parasite, and then move to the digestive tract to feed and reproduce. It would explain the deteroiration of flesh, as the body would be malnourished due to the parasite, and it would explain the zombies being slow and lumbering for the same reason. They're also complex organisms, and would be more likely to exhibit complex behaviors such as this one. Another less known theory is the sentient parasite theory. This one's pretty rare in zombie mythology, and I've only ever seen the idea once (Stargate SG1). The idea is that a species of sentient parasites (usually from outer space) are capable of controlling the brain and would reproduce by transferring its larvae to other humans.
Of these, I think the non-sentient parasite is the most likely to carry a zombie payload.
Now that we've established what types of zombie diseases exist, we need to know how it spreads. There are many ways this disease is supposedly transmitted, and we'll determine whether they're possible, and then whether they're plausible. Since zombie apocalypses occur in as short a time as a couple of weeks, we'll assume that all forms of the disease are transmitted horizontally (not through offspring).
- Airborne Transmission -
Because of the fact that most parasites are many-celled complex organisms, this one is less likely. The extra weight that a many-celled organism has over a virus or bacteria gives them a major disadvantage in terms of being able to fly long distances. However, parasites are very diverse, so the zombie parasite could very well develop some sort of adaptation tat allows it to travel long distances through the air.
- Waterborne Transmission -
If we're talking parasites, this seems more likely than airborne. The fact is, water locomotion is a much more basic form of movement than airborne, and nearly all microscopic organisms live in water or travel through water to get to a host. However, in today's modern world, a parasite would have to find a way around the water purification plants that exist in nearly all first-world countries, and would be less of a pandemic and more of a localized catastrophe (as our water plants are designed to control diseases such as this one).
- Blood/Fluid Transmission -
This one is the most common in pretty much all zombie lore, dating back to the very first zombie movies in the mid 1900's. A bite, scratch, or other blood contact spreads the disease, making more zombies to do the same. Not only is this the most common, but it's also the most likely. The outbreak starts because the parasite takes a while to spread through the blood and infect the host, so people transmit it to each other without knowing there is a zombie disease. As soon as the first case occurs, enough are infected to spread the disease manually. There is no transition phase between infections because transmission is direct, so the disease won't die while traveling from place to place. Finally, the fact is that people will get infected because they are killing the zombies. They'll shoot them or stab them or hit them with a blunt object, and the infected blood will splatter all over the person.
Although all three types of transmission are plausible, we're going to assume that the one we'll be facing is blood transmission. This is because of the fact that water and air-transmitted diseases spread so fast that the only survivors are those who are immune (which gives you as an individual a pretty slim chance). It's so unlikely that you'll survive an airborne disease that we won't plan for it, but instead plan for the one we actually have a chance in.
Appearance/BehaviorWe now know (more or less) what we need to protect our bodies from, but now we need to know what will happen to those who aren't so lucky. How will we tell them from the uninfected populace? How long will it take them to turn? Will they be physically superior or inferior? These are all very good questions, and we'll answer a few of them here.
- Appearance -
This is a difficult topic to cover because there are so many possibilities. They could be covered in boils and hives, be all skin and bone, or look exactly like normal people. It's nearly impossible to say exactly what they will look like, but we can eliminate a few things. For one, they probably won't have glowing eyes, long claw-like nails, canine teeth, or any superhuman strength. These changes would require energy from the host, which it can't spare because it's already using its energy to support the parasite. Also, the changes would require some sort of genetic mutation (which, as far as I know, a parasite couldn't do to a person). What I think are most likely are the following: boils or hives, deteriorated flesh (similar to that of a leper's), missing limbs (see feeding), very skinny with little fat tissue, bald or mostly bald, and missing extremities. Most of the above things are results of either the body's reaction to the foreign organism, signs of malnutrition, or leprosy (the result of the brain's pain center being shut down).
- Fast or Slow? -
A major debate between different zombie lore is zombie locomotion. Some say they'll be able to run, climb, and overcome any obstacle to get food. Others say that they're slow, lumbering creatures that just limp along after you. I think it could go either way. On one hand, they should be slow because they are malnourished and weak. On another hand, the biggest enemies of human endurance are pain and doubt. Because the zombie's pain centers and conscious mind are gone, they experience neither of these, so they basically would run until they catch you or keel over dead. On a third hand, (if that's even possible) it could vary between cases, depending on what the person was like when they were alive, or how the disease affects different people.
- Feeding -
Most zombie stories agree that zombies have to eat. Whether its brains or just flesh in general, its something all living things need to do to survive. If we're following the parasite model, then the host must eat in order for the parasite to survive. A zombie's diet would most likely be made up of meat exclusively, and here's why. The zombie is created by shutting down the parts of the brain that control conscious thought and pain, leaving only those that control basic motor functions, hunger, and basic senses. Primal humans, before they discovered they could eat plants, ate meat exclusively. Therefore, without knowing that plants are edible, zombies would do the same. The Walking Dead shows that after a person is infected, the zombies feed on parts of it (such as limbs or extremities) and the rest of it is reanimated.
So in Part 1 we've established that zombies (at least the ones that we are planning for) will be caused by a bloodborne parasite, and they will be easily distinguishable from the uninfected populace prior to infection. In part 2, we'll learn how to kill them.
The Night of the Living Dead - George A Romero
Left 4 Dead - Valve
Half-Life 2 - Valve
The Walking Dead - Robert Kirkman, Charlie Adlard, Tony Moore, AMC, Telltale Games
Stargate SG1 - Brad Wright, Johnathan Glassner, Metro Goldwyn Myer