Everything You Ever Wanted to Know About Zombies

by Mogk, Matt

  DO THEY EAT DEAD PEOPLE?

  Do zombies eat dead people? The answer may seem obvious, as they are generally considered to be after one thing and one thing only: live flesh. Therefore, a zombie would pass right by an available dead body and continue hunting the living.

  But imagine a group of zombies cornering you in a dead-end alley. You do everything you can to fight back, but eventually, their numbers are too great, and you are driven to the ground by clawing hands and gnashing teeth. The zombies chew on your fingers, rip off a leg, and make short work of your intestines. Soon enough, you die from the overwhelming pain and blood loss, which leads to another version of the same question.

  At the moment your heart stops beating, do the zombies get up and wander off, or do they continue feasting on your lifeless corpse?

  If you think they get up, then zombies don’t eat dead people. But if you think they finish the job, sucking out your eyeballs and chewing on your forearm even after you’ve died, then zombies do at least eat the newly deceased. This may seem like a small point, but it could mean the difference between real hope for civilization’s survival and total world collapse.

  If zombies continue feeding on the dead, then they are effectively destroying their own reinforcements. A person with a deadly bite may rise up to become a zombie himself, but a body that has been chewed down to nothing won’t be physically able to stand and search out new victims. Zombies could quite literally eat themselves out of existence.

  My hope is that they have really big appetites and don’t know when to say when.

  DO THEY EAT ANIMALS?

  It’s often suggested that zombies bite human beings because they are driven to spread their disease to other viable hosts. Because, with rare exception, prevailing wisdom suggests that the zombie virus is likely only communicable to humans, it could be argued that the undead would therefore be drawn to human beings only and ignore all other living creatures.

  But even if the zombie infection is only a threat to humans, it is also a generally accepted belief that zombies aren’t the sharpest knives in the drawer, nor are they attacking the living because of some greater strategy. Zombies do what they do because they are driven to it and don’t know how to do anything else. It’s possible that a hunting zombie might not be able to differentiate between different species and therefore would essentially want to bite anything that moves.

  Romero’s own rules on zombie eating habits have changed over time. In the original Night of the Living Dead (1968), the zombies eat anything alive, including bugs. But in Survival of the Dead (2009), a central plot concern is to train the zombies to eat something other than humans, and for the most part, they seem completely unwilling and uninterested.

  But because zombies are thought not to work together and not to use any tools or weapons, it would be difficult for them to catch most animals in the wild even if they so desired.

  An easy test for this is to go outside and attempt to catch a squirrel, mouse, or rat with your bare hands. Even a cat or a stray dog that doesn’t want to be caught is going to be a nearly impossible goal, especially if you’re not aided by any advance strategy or tools. So zombies may want to eat animals, but if their abilities are limited, as we suspect, then for the most part, it’s just not going to work out for them.

  Good news for your pet ferret Bobo, but you’re still pretty much screwed.

  KNOW YOUR ZOMBIES: TARMAN

  Return of the Living Dead (1985)

  Tarman crawls out of a fifty-gallon drum of toxic sludge with one thing on his mind: brains. A military experiment gone wrong, he is the first modern zombie to ever say “brains” and the first modern zombie to ever eat brains, making him one of the most iconic ghouls of all time.

  William Stout, famed production designer of Return of the Living Dead, later worked on creature design for Predator (1987), Men in Black (1997), and Pan’s Labyrinth (2006).

  ILLUSTRATION BY WILLIAM STOUT

  12: HOW LONG HAVE WE GOT?

  We’ve all seen the unlucky saps in zombie movies who get bitten, fall ill, die soon after, and then come back as undead beasts themselves. But how exactly does the zombie sickness cause such a speedy death in its victims? Turns out your own immune system might do most of the work, acting as a final nail in your coffin.

  Sepsis is a condition in which the body fights a severe infection that has spread via the bloodstream. The immune system goes into overdrive, overwhelming normal processes in the blood and leading to blood clots and organ failure. Patients who become septic must be quickly seen by medical professionals or risk falling into a state of shock. If they are left untreated, death can occur within a matter of hours.

  More than 200,000 people die of sepsis each year in the United States alone, and the symptoms closely mirror those seen in depictions of the progression of the zombie sickness. If a flesh eater’s bite can deliver enough toxic filth to induce septic shock, it doesn’t need to be fatal, because your own immune system will react so violently to the invading sickness that you will essentially kill yourself. In fact, new findings suggest that a bite resulting in infection need not be as directly damaging as previously thought to be fatal.

  A 2010 study of the causes of deadly inflammation at Harvard Medical School found that when the cells in our body are damaged by injury, they release large quantities of mitochondrial DNA. Though harmless, the DNA debris is interpreted by our immune system to be foreign bacterial invaders, and legions of white blood cells are called into action, sometimes with fatal results.

  Therefore, a microscopic zombie sickness could kill a newly infected person quickly without relying on any sophisticated mechanisms. It has only to launch small attacks on cells it doesn’t need for future functions, thereby overwhelming the immune system and sending white blood cells into a deadly panic. Death by septic shock would quickly follow.

  But to really address the question of how long we have, we must look at two factors: the incubation period of the zombie sickness and the zombie life span.

  INCUBATION PERIOD

  As the speed of zombies on the hunt has increased in recent years, so, it seems, has the rate of infection. Rather than a day or even several hours, films such as 28 Days Later present a virus that takes full control of its host in just a matter of seconds. In the case of living zombies, the argument is that it can transform its victims much more quickly because there is no need to go through the traditional process of death and reanimation. But is that logic sound?

  Dr. Natalie Mtumbo of the World Health Organization suggests that the living zombies are in many ways less realistic than their classic undead counterparts. She explains that a disease spreading instantly through the body goes against everything we know about the rules of pathology, and so the notion of an extended incubation period makes more sense, even if it includes death.21

  Echoing this point, Dr. Phil Luton of the United Kingdom’s Centre for Emergency Preparedness and Response asserts that infectious-disease transmission requires an incubation period during which the patient is asymptomatic:

  It has to get into the body. Next it has to take over the body and reproduce itself. It then has to get out of the body again and spread to the next person. Normally for that process to happen would be a minimum of two to three days.22

  In 2005, the United States Centers for Disease Control and Prevention set up a network of training institutes across the country designed to strengthen the nation’s readiness for catastrophic public-health disasters. On condition of anonymity, a senior researcher at one such facility discussed several zombie doomsday scenarios, noting that the impact of infectious disease comes down to four measurable factors: susceptibility, exposure, infection, and recovery (or death), known as the SEIR model.

  Assuming that the entire world is susceptible to the sickness, the researcher said that if zombieism is spread through a bite or some other close bodily contact, then you have a potential exposure problem, and the faster the infection spreads, the less likely
it is to affect a large population.

  He concludes that a lightning-quick virus is not only scientifically unrealistic, but it would draw too much attention to those infected in the early stages ever to represent a serious global threat. Instead, a zombie virus would likely need to have a long latency period, allowing it to infect a wide range of people across the planet before any symptoms appeared.

  Unless the zombie sickness has a long latency period, experts agree that although off the charts in terms of creepiness, it would be considerably less concerning from a public-health standpoint than existing airborne pathogens that can spread easily across great distances.

  If it takes a longer time for human beings to die and turn into flesh-eating ghouls, then it is also possible for them to travel a farther distance from the original point of infection while still human.

  —Theories of International Politics and Zombies (2011), Daniel W. Drezner

  MOSQUITOES

  If the infection does incubate more slowly and methodically, then there could be a troubling scenario at play with regard to its spread. Many blood-borne illnesses are transferred by mosquitoes. Malaria, for example, is almost exclusively passed from one carrier to another in this manner. But mosquitoes do not feed on dead animals or people, suggesting that zombies would not be part of their diet.

  Mosquitoes use various cues to find food, but above all, they are olfactory creatures. Breath and body vapors draw them to their animal hosts, as does body temperature.23 Therefore, it stands to reason that a cold, rotting zombie would look nothing like a warm, living, breathing human to a mosquito.

  However, a newly infected person who is still alive and kicking may be able to spread the infection before he even shows any signs of being sick. If that were the case, and if the zombie incubation period is as long as days or weeks, then entire populations could be infected before anyone even knows there’s a problem.

  Even once a person realizes that he’s sick, a real danger exists that the infection will be hidden from other survivors. Most zombie movies feature at least one infected character who hides his worsening condition from the rest of the group. He gets bitten on the arm and then simply puts a long-sleeved shirt on, pretending nothing ever happened. Filmmakers use this device to heighten drama and drive action, but in a real zombie outbreak, failure to identify and isolate the sick could mean certain death. And you can bet many infected won’t be eager to announce their new death sentence to the world.

  THE ZOMBIE LIFE SPAN

  The zombie life span is a key element of survival research, because if an accurate timeline can be established, starting with reanimation and ending with the final stages of decomposition, then strategies and expectations can be adjusted accordingly, resulting in millions of lives saved.

  First, it’s important to note that by human physiological standards, zombies are dead. They are believed to have no heartbeat, their blood is cold, and their tissue is in a state of decay. So it stands to reason that by looking at the specifics of human decomposition, we can come closer to the truth about how long the modern zombie can function before rotting back into the earth.

  The human corpse goes through several distinct stages of decay, including fresh, bloat, and putrefaction. In her 2004 New York Times bestseller, Stiff, Mary Roach clearly breaks down this progression, noting that a hallmark of fresh-stage decay is a process called autolysis, or self-digestion. Roach goes on to explain that all of the body’s internal organs liquefy in the fresh stage, including the brain.

  In fact, because the brain is so soft and so close to hungry bacteria in the mouth, it is one of the first organs to go. By the second stage of decomposition, bloat, the brain has already been turned into a worthless puddle of mush, unable to keep from leaking out of the nasal cavity, much less control the actions of a bloodthirsty zombie. Therefore, it seems likely that a zombie’s life span lasts as long as the fresh stage of decomposition and not one moment longer.

  Dr. Peter Cummings is a forensic pathologist and medical examiner at the Massachusetts Office of the Chief Medical Examiner and author of The Neuropathology of Zombies. His research suggests that the rate of decay could be significantly slowed in the undead, resulting in a life span that doesn’t last weeks or months but years or even decades:

  I think they may be rotting at a much slower pace, like the foot of a diabetic. Their feet rot and toes fall off, but it happens over time. I also think that by having some basic metabolism, and some electrical stimulation to the muscles, they can decompose much slower.

  If the undead do rot at a much slower pace than their human counterparts, zombie blood itself could act as a preservative. Embalming fluid makes the body’s cellular proteins toxic, so they can’t act as a nutrient source for invading bacteria. If the body fluids in a zombie are toxic, as is widely believed, it is possible that the system acts in a similar fashion to embalming fluid, thus slowing down decomposition considerably.

  No matter what the process, it’s highly unlikely that zombies survive indefinitely. If nothing else, exposure to the elements over time would break down the undead body from the outside in. Flesh would eventually wear away, and bone would become brittle and prone to breakage.

  But if zombies don’t decay from the inside out as dead humans do, if they are not susceptible to the same hungry bacteria that turn our dead organs into mush in just a matter of days, then the critical window of survival may be much longer than anyone previously thought.

  ZOMBIE SLEEP

  A 2009 sleep experiment from the University of Chicago proved that after thirty days of total sleep deprivation, a seemingly healthy rat will drop dead. In fact, all complex animated creatures—humans, rats, sheep, cockroaches—need some form of regular sleep cycle to stay alive.

  These findings suggest that zombies may be able to slow their cellular breakdown by mimicking the survival techniques of the living. However, this doesn’t necessarily mean a traditional, tucked-in-bed, eight-hour recharge for our undead friends.

  Think of it as the standby mode on your computer. The machine hasn’t shut down completely but is in a holding pattern, allowing it to last longer and run more efficiently when booted back up. Many insects and fish species act similarly, and so, too, may zombies. This would explain why they are often seen to be hardly moving at all when not in pursuit of prey.

  Biologist Michael Harris suggests that zombies may be exhibiting a form of reduced metabolic state distinct from sleep, called mammalian torpor:

  Torpor is a part of hibernation which, when exhibited by small mammals, leads to much reduced metabolism and reduced responsiveness. When exhibited by large mammals the result is reduced metabolism and increased longevity, but with maintained responsiveness.

  So the next time you spot a zombie milling about aimlessly, don’t just assume it’s too stupid or slow to do anything else. Maybe it’s just recharging so it can be refreshed and ready when the next tasty meal happens by.

  RIGHTS OF THE INFECTED

  If a person infected with zombie pathogens shows no sign of illness for an extended period of time, then there are many important questions to address. What are the rights of the infected? What liberties should be granted to people who have contracted the zombie illness but are not yet dead or dying? Who gets Bill’s stuff once we blow his head off?

  If society does not collapse under the weight of a zombie pandemic, then the problem of what to do with thousands, or even millions, of friendly, everyday folk who just happen to have contracted a slow-acting, contagious disease that will eventually turn them into undead beasts may well become very real and very persistent. Do we shoot them on sight? Do we lock them up and throw away the key? What if they can live regular lives, with no sign of illness, for years? What if they can’t even pass on the contagion until the very latest stage of their own progression?

  In the closest model for this potential reality, John Tayman’s bestselling work, The Colony, chronicles a dark chapter in Hawaiian history when thousands of
lepers were forced to live on a remote island, separated from their families and doomed to eke out their remaining days in deplorable conditions. Their sickness was ruled an illegal act, their rights were stripped, and they were treated as living corpses:

  The patients were judged to be civilly dead, their spouses granted summary divorces, and their wills executed as if they were already in the grave.24

  No matter how they were legally defined, the lepers were still alive when they were shipped away from the world. In fact, many lived years or decades in isolation, making them the first true example of the walking dead. It takes little imagination to see that the governmental and public response to the dreaded leprosy of old may be shockingly similar to that of the coming zombie pandemic.

  But if she was bitten, and thus infected by an Unconsecrated, there are only two options. Kill her now or imprison her until she turns and then push her through the fence.

  —The Forest of Hands and Teeth (2009), Carrie Ryan

  The current malaria pandemic is a contemporary reminder of the challenges we will likely face when dealing with the rights of the infected. The World Health Organization estimates that there are as many as 500 million cases of malaria with more than 1 million resulting deaths each year. In fact, in Africa, a child dies from malaria every thirty seconds, and because the disease is transmitted by mosquito, it infects new victims without their knowing. Even though malaria patients are not themselves contagious, meaning that the disease cannot be transmitted directly from person to person, many face poor treatment upon diagnosis. They are locked away from society, stripped of their rights, and left to die in what amounts to sealed prison cells. This does nothing to stop the spread of the disease but is simply an irrational reaction to the public’s fear and panic.