I must admit I wrestled with the idea of including the topic of zombies in a science blog. I have always disparaged the public’s penchant to lend equal credence to supernatural and pseudo-scientific ideas, as it does to the results of scientific investigations, and I have no desire to encourage that tendency with this blog. However, when I discovered that no less a scientific authority than the U.S. Centers for Disease Control and Prevention (CDC) has a website addressing methods for surviving the coming zombie apocalypse, I reconsidered. What’s good enough for that august organization surely must be good enough for me!
The working definition of a zombie is a reanimated human being. That obviously supposes that the creature was once dead, and is now alive, or at least undead, if you prefer. Zombies are generally depicted as mindless eating machines with an inexplicable taste for human flesh, although some traditions attribute them with rudimentary intelligence, or nefarious intentions imparted by the evil sorcerer that controls them.
It is generally agreed that the current zombie craze started in 1968 with the release of George Romero’s Night of the Living Dead (1968), although cinematic zombies have been around far longer. The redoubtable Bela Lugosi starred in White Zombie as early as 1932. Howard Phillips Lovecraft published his classic story Herbert West – Reanimator ten years earlier. At least one academician regards the current Zombie fad as a symptom of societal illness, while others see it as a coping strategy for our deepest fears. However, it is a fact that humans have believed in the return of the dead as monsters to plague the living since antiquity –Haitian and African zombie legends and the vampire legends of Eastern Europe are well-known examples. Regardless of the cause, it is undeniable that the current zombie craze is big business. One estimate of its contribution to the economy is as high as 5 billion dollars.
It is interesting to consider whether there is any scientific basis for the existence of zombies. While the definition of death has changed over the years with the advancement of medical technology, it is obvious that a condition characterized by the irreversible cessation of all biological functions exists. Nevertheless, modern technology allows recovery from many conditions that would have been mortal not that many years ago. Cases of spontaneous recovery from seemingly fatal conditions were apparently common enough in Victorian times to cause a fear of premature burial that was so pervasive in that culture, it even led to the manufacture of coffins that could be opened from the inside.
Numerous toxins and diseases that could cause the appearance of a dead man returning to wreak havoc on the living also exist. Not all cases of intoxication or infection with these agents produce identical symptoms, but a particular symptom complex that would give the appearance of reanimation could certainly be imagined. A person living in a primitive society might attribute such symptoms to supernatural causes, having no information to the contrary.
Ergot is a fungus that grows on grain crops when climatic conditions are favorable. Ergot poisoning of populations that consumed grain from the same contaminated source has been documented, and implicated in apparent outbreaks of lycanthropy in Europe, as well as the accusations of witchcraft in Salem, Massachusetts in the 1600s. The symptoms of ergotism are both neurological and dermal (it causes gangrene), so it is easy to see how the image of a rotting dead thing with a shuffling gait could be evoked from a case of ergot poisoning.
There are several modern drugs which could induce a similar state. One of the scariest is a narcotic known as Krokodil (Desomorphine), a street drug in Russia and Eastern Europe that has recently appeared in America. The preferred route of administration for Krokodil is subcutaneous (i.e., skin-popping). Since its manufacture is underground, purification is minimal and the final product sold to addicts is generally heavily contaminated with toxic and even corrosive substances, which cause necrosis of the skin surrounding the injection sites. A committed user could easily resemble a decomposing, undead creature with minimal awareness. Another opiate, known as black tar heroin, can have similar effects. Like Krokodil, it can contain dangerous impurities, and has been documented to destroy veins if injected intravenously, which leads many users to prefer subcutaneous injection. However, subcutaneous use can predispose users to necrotizing skin infections.
Scopolamine is another illicit drug being used as a weapon by criminals, because intoxication essentially causes a loss of conscious choice. Much anecdotal evidence suggests that it is employed on a significant scale in South America to cause victims to give money, sexual favors and other things to perpetrators who surreptitiously dose them. It isn’t documented to have dermal effects, but it does induce a state of mindlessness, allowing the kind of control over its victims ascribed to the juju man who creates a zombie. Other, so-called date-rape drugs, (e.g., Flunitrazepam (Rohypnol), GHB, (gamma hydroxybutyric acid), Ketamine) are used voluntarily as street drugs or administered surreptitiously to induce similar effects.
Several diseases also produce symptoms similar to zombie behavior. In theory, any disease that causes delirium could transform a sufferer into a zombie-like state. Mental or neurological conditions, such as somnambulism or catatonia, can also produce similar outcomes. An accompanying skin disorder would complete the picture. Indeed, infectious disease is the favored vehicle of fiction writers to explain the occurrence of a zombie plague, although no communicable disease has yet been documented to reproducibly produce a set of such symptoms in a large population of infected individuals. So, regardless of CDC’s trepidations, it doesn’t look as if a widespread zombie plague is on the horizon anytime soon.
Still, how can it hurt to be prepared?