Maybe, but it's not going to be easy. In West African and Haitian vodou, zombies are humans without a soul, their bodies nothing more than shells controlled by powerful sorcerers. In the 1968 film Night of the Living Dead, an army of shambling, slow-witted, cannibalistic corpses reanimated by radiation attack a group of rural Pennsylvanians. We are looking for something a little in between Haiti and Hollywood: an infectious agent, a zombie virus if you will, that renders its victims half-dead but still-living shells of their former selves.
See our gallery of real live zombies in nature.
An effective agent would target, and shut down, specific parts of the brain, says Steven C. Schlozman, an assistant professor of psychiatry at Harvard University and author of The Zombie Autopsies, a series of fictional excerpts from the notebooks of "the last scientist sent to the United Nations Sanctuary for the study of ANSD," a zombie virus. Schlozman explained to PopSci that although the walking dead have some of their motor skills intact—walking, of course, but also the ripping and tearing necessary to devour human flesh—the frontal lobe, which is responsible for morality, planning, and inhibiting impulsive actions (like taking a bite out of someone), is nonexistent. The cerebellum, which controls coordination, is probably still there but not fully functional. This makes sense, since zombies in movies are usually easy to outrun or club with a baseball bat.
The most likely culprit for this partially deteriorated brain situation, according to Schlozman, is as simple as a protein. Specifically, a proteinaceous infectious particle, a prion. Not quite a virus, and not even a living thing, prions are nearly impossible to destroy, and there's no known cure for the diseases they cause.
The first famous prion epidemic was discovered in the early 1950s in Papua New Guinea, when members of the Fore tribe were found to be afflicted with a strange tremble. Occasionally a diseased Fore would burst into uncontrollable laughter. The tribe called the sickness "kuru," and by the early '60s doctors had traced its source back to the tribe's cannibalistic funeral practices, including brain-eating.
Prions gained notoriety in the 1990s as the infectious agents that brought us bovine spongiform encephalopathy, also known as mad cow disease. When a misshapen prion enters our system, as in mad cow, our mind develops holes like a sponge. Brain scans from those infected by prion-based diseases have been compared in appearance to a shotgun blast to the head.
Now, if we're thinking like evil geniuses set on global destruction, the trick is going to be attaching a prion to a virus, because prion diseases are fairly easy to contain within a population. To make things truly apocalyptic, we need a virus that spreads quickly and will carry the prions to the frontal lobe and cerebellum. Targeting the infection to these areas is going to be difficult, but it's essential for creating the shambling, dim-witted creature we expect.
Jay Fishman, director of transplant infectious diseases at Massachusetts General Hospital in Boston, proposes using a virus that causes encephalitis, an inflammation of the brain's casing. Herpes would work, and so would West Nile, but attaching a prion to a virus is, Fishman adds, "a fairly unlikely" scenario. And then, after infection, we need to stop the prion takeover so that our zombies don't go completely comatose, their minds rendered entirely useless. Schlozman suggests adding sodium bicarbonate to induce metabolic alkalosis, which raises the body's pH and makes it difficult for proteins like prions to proliferate. With alkalosis, he says, "you'd have seizures, twitching, and just look awful like a zombie."
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