In later films and books of the genre, the other storytellers recognized the logical need to address this and established that the plague is spread through direct infection, specifically through the exchange of fluids during a bite. And this is necessary in order for the films and books to continue to be frightening, and indeed to become even more frightening. Otherwise it’s fantasy, and we’re much too jaded these days to get spooked by something that has no possibility of ever coming true. We need at least some measure of plausibility.
The burden is on the filmmakers and authors to create a framework on which a plausible story can be built. Throw the audience a bit of a bone, logic-wise, and they’ll allow for a lot; insult the intelligence of an audience by denying them any reasonable scientific structure, and their mood gets ugly real fast. And I don’t blame them one bit. There are whole books written on the inaccuracies in classic and beloved shows like Star Trek, The X-Files, Buffy…and online message boards are ablaze with postings about everything from continuity errors (like Han Solo’s now-you-see-it, now-you-don’t vest in Empire Strikes Back), to technical flubs (the entire crew leaving the Sulaco to go down to the planet in the film Aliens), to outright scientific impossibilities (Daredevil doing gymnastics and intense fighting after having been stabbed through the shoulder—he has heightened senses, not a mutant healing factor!).1
Most monsters can be scientifically understood, at least to some degree. Werewolfism—overactive hair follicles notwithstanding—has been heavily documented, particularly in court cases involving a person tried for werewolf murders. Anyone who understands abnormal psychology and who reads the many transcripts of those trials will see a clear pathology indicating sociopathic behavior. What the courts called a “werewolf” four hundred years ago would very clearly be called a serial killer today.
The legends of a mysterious invisible night-predator sneaking into the bedrooms of children by night and stealing their breath is what our ancestors called vampires but which we call sudden infant death syndrome. The belief of a soul-stealing old hag who comes in the night to torture men is now understood as sleep paralysis. Granted, not all the things that go bump in the night have been (so far) explained away, but someone grounded in science and using an open mind can work up a really good set of explanations for most of them.2
Zombies, though they are creatures of fiction rather than folklore, can also be reasonably understood. Except for a twitch here and there, Romero did a solid job of giving us a set of guidelines to understand the zombies. He is a very smart man and a terrific storyteller, and though he’s not a scientist, he did try to make sure scientific plausibility existed within the framework of his undead world. In his films it’s established that:
Zombies are not alive. They are the recent dead brought back to some kind of semblance of life, but they are definitely corpses.
Zombies don’t breathe. Maybe some of them have been shown to have throats torn away, gaping chest-cavity wounds, etc.
Zombies don’t think. Not (at least) until the third movie, and then more so in the fourth. This suggests that a process of change is ongoing in the zombies and that cognitive powers may be returning to them.
Zombies can’t be wounded (only killed). Lop an arm off, riddle their bodies with bullets and you get bupkiss. Put a round through the brainpan and the ghoul goes down.
Zombies can be killed only by severe trauma to the brain. This suggests that the central nervous system functions to some degree.
For this chapter I approached a number of experts in various medical and scientific fields to see if we can get a better scientific view of what zombies are and what makes them do what they do.
JUST THE FACTS
Neurology and the Living Dead
The first problem to solve is: Are zombies truly dead, partly alive, or something else? Personally, I’m leaning toward “something else,” some state between clinical death and actual life.
Let’s discuss death. It’s not just an end to life—which is both a medical and philosophic issue—death is also a process during which the body undergoes remarkable change. The dead are by no means static, they’re not frozen in time. Death begins the instant the heart stops beating. Without blood flow no oxygen goes to the cells. The brain cells are one of the first to die in the absence of oxygen, and the skin cells are among the last. Depending on temperature, the presence of insects, and other factors, this process may occur at different speeds. When the heart stops beating, blood no longer flows and begins to settle, draining from the highest points to the lowest point due to gravity. The upper skin surface is pale as blood drains, and the lower parts of the body darken as that blood collects. The now inert cells no longer produce the molecular movement needed to energize the biochemical processes in the muscles. Calcium ions leak into the nonenergetic muscle tissue and prevent them from relaxing normally, and therefore stiffen. This muscular rigidity is called rigor mortis and it kicks in about three hours after death and will keep the body as stiff as a statue for about thirty-six hours. As more and more cells die, the body’s capacity to fight off destructive bacteria fails; and then the enzymes in the muscles, coupled with the now uncontrolled bacteria, begin to decompose the muscles, which ultimately cause the muscle integrity to fail, and the body becomes limp again.
During this time the body’s temperature steadily cools. On average it takes about twelve hours for a corpse to become “cool” to the touch; and a full day for it to cool all the way to the core.
Are zombies dead? Do they fit the criteria? If we take the Romero zombies as the basis for our discussion, we have to assume that some aspects of reported zombie behavior must be dismissed. For starters, there is no way an embalmed corpse will rise. Nope, no way. I’m going to mark that down to bad reportage from hysterical and therefore unreliable witnesses.
I posed the question of zombie reanimation to my experts. They weren’t as dismissive of the whole idea as you might think. In fact, they collectively built a pretty strong case for how a zombie might operate. Strong enough to be deliciously creepy.
Let’s start by discussing the anatomy and function of the human brain, which is essentially an electrical and chemical machine, weighing only three pounds and containing about 100 billion cells. Most of these cells are called neurons and serve basically as on/off switches to conduct electrical impulses. Neurons are either transmitting signals (on) or resting (off). Each neuron has a cell body, a kind of conducting wire called an axon, and a pump for shooting out neurotransmitters that cross a gap between neurons (called a synapse) and are received by a receptor (called a dendrite), where the neurotransmitter triggers the next neuron to continue sending the signal. Different neurons use different types of transmitters, including epinephrine, norepinephrine, dopamine and others. Collectively, the electrical charge from these billions of axons generates a charge equal to a 60-watt lightbulb (give or take). Devices such as the electroencephalograph (EEG) can track and measure this electrical activity.
* * *
PMI: Calculating the Postmortem Interval
The timetable for the process of death and decay is important to all aspects of murder investigation. It unfolds like this:
Algor mortis: (Latin: algor—coolness; mortis—of death) The process a body goes through after death during which the body cools to ambient temperature. Temperature drops at approximately 1 to 1.5 degrees Fahrenheit per hour.
Rigor mortis: (literally “death stiffness”) The stiffening of the limbs following death as muscle cells decay.
Vitreous humor changes: There is a clear gel that fills the gap between the retina and the lens of the eye. Following death the potassium levels in this gel increases at a measurable and predictable rate, which allows forensics experts to use it to measure time elapsed since death.
Entomology: Insects always appear on a corpse and are crucial to its decomposition.
Autolysis: (literally “self-splitting”) This is the process of postmortem cell disintegration.
Putrefaction: The decomposition of proteins by anaerobic microorganisms called putrefying bacteria.
* * *
Most of the cranial cavity is filled by the cerebrum, a large rounded structure divided into two hemispheres, and each hemisphere is further divided into four sections, the frontal, parietal, temporal, and occipital lobes. The two hemispheres are primarily linked to the corpus callosum (a very large bundle of nerve fibers) through which the two “half brains” communicate with each other. This commissure transfers information between the two hemispheres to coordinate localized functions. The cerebrum controls a variety of functions (motor, sensory, and higher mental functions, such as thought, reason, emotion, and memory) and integrates their actions. It consists of both gray and white matter. The gray matter is mostly composed of neurons (cell bodies) while the white matter primarily contains axons (nerve fibers). The majority of the cerebrum consists of white matter.
* * *
Zombie Oops!
“Using the mythology Romero put forth I realized there is a small problem. In both versions of Night of the Living Dead Johnny (brother of the female lead, Barbara) dies by his head being crushed. This would have damaged the brain, and since that is how to stop a zombie in the first place it makes you wonder how he came back in the first place.”—Damien Rogers, zombie movie fan
* * *
Each hemisphere has an outer layer of gray matter called the cerebral cortex. The motor cortex is the part of the cerebral cortex in the brain that controls the actions of voluntary muscles; different parts of the motor cortex control different specific muscle functions. It can be presumed that in zombies there is some function of the motor cortex. The jerky movements and (in some cases) apparently dead limbs are indications of damage to this center of the brain or perhaps the cerebellum.
In the cerebrum, there are fifty to one hundred thousand neurons; information is sent from place to place like a telegram. The neuron cell bodies would be the telegraph machine itself while the axons would be the wires connecting it to other machines.
The right hemisphere organizes or sorts information; the left hemisphere analyzes the information collected by the right.
Certain mental functions (e.g., mathematics, logic, language) are lateralized in the brain, meaning they are located in either the right or left side of the brain. Generalizations are made about these functions (e.g., logic, creativity), but they need to be treated carefully because popular lateralizations are often distributed across both sides. Lateralization of these functions also depend on whether or not the person is right-handed versus left-handed. Since the majority of people are right-handed, the distribution of mental functions (see the sidebar, “Brain Function”) is done with that in mind (in a left-handed individual, the lateralization is usually located in the opposite hemisphere from that of someone who is right-handed).
* * *
Art of the Dead—Kelly Everaert
Zombie Biohazard
“Night of the Living Dead scared the crap out of me. I was probably ten or eleven watching the late night movie on Halloween after a night of trick or treating. At least one channel played this classic movie every Halloween and I’ve watched it every year since.”
* * *
* * *
Brain Function
Left Hemisphere Functions
Right Hemisphere Functions
sequential
simultaneous
analytical
holistic
verbal
imagistic
logical
intuitive
algorithmic processing
algorithmic processing
perception of counting/measurement
perception of shapes/motions
present and past
present and future
grammar/words, pattern perception, literal
intonation/emphasis, prosody, pragmatic, contextual
* * *
The best example of lateralization for one specific ability is language. Both sides contain major areas in language skills, but each have separate properties. Linear reasoning functions of language (e.g., grammar, word production) is lateralized to the left hemisphere while holistic reasoning (e.g., emphasis, prosody) are lateralized to the right hemisphere.
In general terms, the left brain deals with logic and analytical ideas while its counterpart deals with imagination and abstract ideas. (If one side of the brain is injured, it affects the other.) So, someone with an injury to the right hemisphere of the brain might not be able to make correlative thoughts: They might see a wall and not comprehend that they need to find a door to get through it, and instead they try to walk through it. Injure the left side of the brain, and a person might lose the ability to solve complex problems.
Human movement is controlled by a part of the motor cortex called the motor strip (or precentral gyrus). Often stroke victims will have some damage to that portion of the brain and lose function in certain parts of the body. Injure the left hemisphere, and the right side of the body will be affected, and vice versa. This is why half of a person’s face sometimes droops following a stroke.
The cerebellum, a cauliflower-shaped structure located just above the brainstem, is the part of the brain governing the higher functions of motion, including posture, balance, and coordination; there is some research indicating that it contributes to some non-motor functions such as active thought (cognition) and emotion. This part of the brain comprises only 10 percent of the brain’s total mass but contains half of the total neurons.
Damage or dysfunction to the cerebellum can result in cerebellar ataxia: ataxia (gross incoordination of muscle movements causing jerky rather than smooth muscular movement), hypotonia (poor muscle tone), asynergy (lack of coordination), dyschronometria (difficulty in measuring time), dysdiadochokinesia (inability to perform rapid, alternating movements), dysmetria (impaired ability to regulate the distance, power, and speed of an act), gait disturbances (abnormal walking patterns), abnormal eye movements, and dysarthria (poor articulation). Kind of sounds familiar, doesn’t it?
Different abnormalities manifest themselves depending on which cerebellar structures are damaged. Vestibulo-cerebellar dysfunction presents with postural instability; the person tends to separate his feet on standing to gain a wider base. Spino-cerebellar dysfunction presents with a wide-based “drunken sailor” gait, characterised by uncertain start and stop motions with unequal steps. Cerebro-cerebellar dysfunction presents with disturbances in carrying out voluntary movements (e.g., intention tremors), writing difficulties (e.g., large, unequal lettering with irregular underlining), and dysarthria (slurred speech).
The brain stem is the portion of the brain that connects the spinal cord to the forebrain and cerebrum. It consists of the medulla oblongata, pons, and midbrain. But it’s more than just an organic coaxial cable; the brain stem relays specific categories of movement commands from the motor cortex. If the cortex wants the arm to wave, the brain stem transmits the message and coordinates the movement. Processes such as mastication are directed by the brain stem, and if you aren’t up on your Latin, mastication is the act of chewing. One thing all zombies do is chew.
The cerebrum is vital for perception and conscious action, but it’s the brain stem that runs the body in the absence of artificial life support. Even if everything above the midbrain is destroyed or shut down, the brain stem will sustain a living body. This is not, of course, “life” as we know it.
Collectively the brain and spinal cord are known as the central nervous system. It is reasonable to assume that for zombies to be animated some parts of this complex system need to be active. Minimally active, to be sure, but somewhere there are some organic switches in the “on” position.
* * *
Zombies…Fast or Slow? Part 4
“Slow, absolutely. They’re dead; their muscles have atrophied, so none of them are going to run the hundred-yard dash in under forty seconds. Jeez!”—Gary A. Braunbeck,
Bram Stoker Award winner and author of Prodigal Blues and Mr. Hands
“I prefer the slow, plodding variety—to me, their mindlessness is their appeal. If they were intelligent, they would simply round up humans and breed them like cattle instead of mindlessly eradicating their food supply. Though their cookbooks might prove interesting.”—Scott Nicholson, author of They Hunger and The Home
“I prefer both slow and fast zombies, so I can race them like the Tortoise and the Hare and see who catches my grandma first.”—D. L. Snell, author of Roses of Blood on Barbed Wire
* * *
Expert Witness
“We see limited and reduced brain function fairly frequently,” says Russ Hassert, MS, a wire service medical news reporter. “I contributed to a number of stories after the Brookhaven National Laboratory released a couple of studies showing that methamphetamine (“speed”) users demonstrated reduced motor and cognitive functions. The studies conclusively showed that methamphetamines taken in amount consistent with habitual abuse reduces the function of the dopamine transporters. Granted, these are not zombie stories, but they establish that there are ways that the brain’s functions can be reduced and the person still be able to function on some level.”