In a memorable moment from George Romero’s 1978 movie Dawn of the Dead—which is sort of The Godfather: Part II of zombie apocalypse flicks—some of the ordinary humans fleeing the growing onslaught of reanimated, cannibalistic corpses pause to ponder a nagging question.
FRAN: What the hell are they?
PETER: They’re us, that’s all. There’s no more room left in hell.
PETER: Somethin’ my granddaddy used to tell us…You know Macumba? Voodoo…Granddaddy was a priest in Trinadad. Used to tell us…When there’s no more room in hell…the dead will walk the Earth.
And hey, in a macabre, twisted sort of way, that actually is an appealingly simple, straightforward explanation. When there’s no room left in hell, the dead will walk the Earth. The whole existential panic turns out to be just a simple equation driven by scarcity of resources, just as in the days before that suburban shopping mall became a refuge from hordes of entrail-gnawing ghouls, suburban moms in station wagons would come into conflict over the precious few remaining parking spaces.
At least that’s the way it works in Romero’s horrifying alternate reality. But what about our actual one? Is there any even remotely plausible scenario in which the undead actually could rise and attack the rest of us in an effort to satisfy their craving for human innards tartare?
It’s a question worth pondering, if only because an actual scientific study published in 2009, “When Zombies: Attack! Mathematical Modeling of an Outbreak of Zombie Infestation,” concluded that a zombification outbreak would quickly escalate into a global catastrophe that would threaten the human race’s existence. And that’s even if every deer hunter in Pennsylvania was deputized as a zombie executioner. The takeaway:
While aggressive quarantine may eradicate the infection, this is unlikely to happen in practice. A cure would only result in some humans surviving the outbreak, although they will still coexist with zombies. Only sufficiently frequent attacks, with increasing force, will result in eradication, assuming the available resources can be mustered in time.
Yet still, you scoff, because zombies don’t exist, except in Haitian folklore, horror movies and TV shows. But that’s where you may be making a fatal mistake. Don’t forget that ethnobotanist Wade Davis, author of the 1985 book The Serpent and the Rainbow, came up with a possible science-based explanation for the Haitian zombie myth. Davis obtained samples of powder from voodoo priests and found that the mixtures included the flesh of puffer fish, whose skin and organs are laced with tetrodotoxin, a potent neurotoxin. In small doses, terodotoxin can slow heartbeat and respiration to death-like levels and induce paralysis. The unlucky victim who ingested the powder would appear to die—only to awaken later in a hallucinogenic haze induced by another of the sorcerers’ concoctions: a paste made of sweet potatoes, cane syrup and datura—a plant containing the psychoactive chemicals atropine and scopolamine.
There’s also a possibility, however remote, that a zombie pandemic could be triggered by a naturally-occuring pathogen. Science journalist, Yale University lecturer and author Carl Zimmer wrote this intriguing 2006 blog post about Toxoplasma gondii, a tiny parasite that is passed from rats to cats who eat them, and then back to rats who feast upon feline poop. The parasite apparently optimizes it’s opportunity to survive and spread, Zimmer notes, by somehow altering the brain chemistry of rats, in a way that causes them to abandon caution and wander recklessly into the open where they can easily be stalked and eaten. What if an analogous parasite suddenly emerged to take over our brains, and turn us into feeble-witted, drooling cannibals as part of a sort of hive-mind scheme to achieve world domination? As Zimmer points out, half the human population of the planet is already infected with toxoplasma, though it only becomes a menace in pregnant women and those with compromised immune systems.
Another disturbing scenario is a manmade zombie pandemic. As investigative journalist John Marks documented in his book, The Search for the Manchurian Candidate, U.S. government scientists spent much of the Cold War trying to develop a mind-control drug that would turn enemy armies into disoriented, helpless, easily-manipulated captives—which, now that we think about it, sounds a lot like zombieism, doesn’t it?As this 2003 article from The Nation details, Russian security forces apparently used a behavior-altering chemical weapon against Chechen terrorists who had seized a Moscow theater, in a failed attempt to capture them without endangering their hostages. (Instead, the gas may have killed many of the innocent people trapped inside.) The Nation also reported that the Pentagon’s Joint Non-Lethal Weapons Program was trying to develop similar psychoactive weapons, and had investigated the use of ketamine, a hallucinogenic drug sold illegally in the street as “Special K.” What if terrorists or some megalomaniac dictator someday got hold of such a mind-control weapon, and somehow dosed a large portion of the U.S. population?
That’s a scenario as frightening as any low-budget horror movie director could come up with.