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The thought experiment: How can I survive a zombie apocalypse?

Survivors of The Walking Dead, take note.

1. Head for the hills

The spread of zombie disease can be modelled using epidemiological simulations. A 2015 study at Cornell University found that cities would be almost completely infected within a week but remote mountains would be untouched after four months. The reproduction ratio (R0) is the average number of new infections that each zombie creates. If R0 is between zero and one, the epidemic will eventually die out.

If the zombies need to eat brains to survive, humanity may be able to simply wait out the crisis. A human brain only contains a maximum of around 2,000 calories, so even the slow and shambling kind of zombie will need to feed every few days just to maintain its metabolism. And any humans that are eaten can’t rise to become new zombies, so the disease would also spread more slowly.

3. Fight back

Conversely, a 2009 study at the University of Ottawa predicted that even if a cure for the virus is found, zombies will eventually overwhelm the population by infecting us faster than we can be treated. Of the possible scenarios, the only one with a happy ending gave us just 10 days to destroy all the zombies, with a series of increasingly devastating counter-attacks.

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The Curious World of Zombie Science

Zombies seem to be only growing in popularity, and I’m not talking about the biological kind

Sarah Zielinski

Zombies seem to be only growing in popularity, and I'm not talking about the biological kind . They've got their own television show , plenty of films , and even a musical . They invaded the world of Jane Austen, and there are zombie crawls around the world, in which people dress up like the living dead and shuffle across some urban area.

And then there's the growing field of zombie science.

In 2009, University of Ottawa mathematician Robert J. Smith? (and, yes, he really does include a question mark at the end of his name) published a paper in a book about infectious disease modeling titled "When Zombies Attack! Mathematical Modelling of an Outbreak of Zombie Infection" ( pdf ). It started as a class project, when some students suggested they model zombies in his disease modeling class. "I think they thought I'd shoot it down," Smith told NPR , "but actually I said, go for it. That sounds really great. And it was just a fun way of really illustrating some of the process that you might have in modeling an infectious disease." Using math, the group showed that only by quickly and aggressively attacking the zombie population could normal humans hope to prevent the complete collapse of society.

That paper sparked further research. The latest contribution, "Zombies in the City: a NetLogo Model" ( pdf ) will appear in the upcoming book Mathematical Modelling of Zombies . In this new study, an epidemiologist and a mathematician at Australian National University refine the initial model and incorporate the higher speed of humans and our capacity to increase our skills through experience. They conclude that only when human skill levels are very low do the zombies have a chance of winning, while only high human skill levels ensure a human victory. "For the in-between state of moderate skill a substantial proportion of humans tend to survive, albeit in packs that are being forever chased by zombies," they write.

Then there's the question of whether math is really the most important discipline for surviving a zombie attack.

But how might zombies come about? There are some interesting theories, such as one based on arsenic from Deborah Blum at Speakeasy Science . Or these five scientific reasons a zombie apocalypse could happen, including brain parasites, neurotoxins and nanobots.

A Harvard psychiatrist, Steven Schlozman, broke into the field of zombie research and then wrote The Zombie Autopsies: Secret Notebooks from the Apocalypse , which blames an airborne contagion for the zombie phenomenon. The book delves into the (fictional) research of Stanley Blum, zombie expert, who searched for a cure to the zombie epidemic with a team of researchers on a remote island. (They were unsuccessful and succumbed to the plague, but nicely left their research notes behind, complete with drawings.) It's more than just fun fiction to Schlozman, though, who uses zombies to teach neuroscience. "If it works right, it makes students less risk-adverse, more willing to raise their hands and shout out ideas, because they’re talking about fictional characters," he told Medscape .

For those interested in getting an overview of the science, a (spoof) lecture on the subject, Zombie Science 1Z , can now be seen at several British science and fringe festivals. Zombiologist Doctor Austin, ZITS MSz BSz DPep, lectures in three modules: the zombieism condition, the cause of zombieism, and the prevention and curing of zombieism. And for those of us who can't attend in person, there's a textbook and online exam.

And the Zombie Research Society keeps track of all this and more, and also promotes zombie scholarship and zombie awareness month. Their slogan: "What you don't know can eat you."

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Sarah Zielinski | | READ MORE

Sarah Zielinski is an award-winning science writer and editor. She is a contributing writer in science for Smithsonian.com and blogs at Wild Things, which appears on Science News.

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Could Scientists Really Create a Zombie Virus

By Ryan Bradley

Posted on Feb 24, 2011 7:22 PM EST

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.”

Have a science question you’ve always wondered about? Email [email protected]