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Science Behind the Fiction: How could zombies actually rise up?

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Feb 6, 2018

It's rare that a creator comes along and makes something so special, so influential, that it changes the landscape of popular culture forever. That's precisely what happened in the autumn of 1968 with the release of Night of the Living Dead.

Like a plague of flesh eating corpses, George A. Romero, altered the landscape of the horror genre forevermore.Night of the Living Dead wasn't the first zombie flick, not by a long shot. That honor goes to White Zombie (1932) starring Bela Lugosi, but even that is a matter of semantics. The zombies present therein are zombies in name only, hearkening back to alleged Haitian voodoo tradition.

 

Zombies, as we know them today, were born with Romero, crafted and molded by him. Everything you take for granted of the walking dead you owe to him and to that film. The shambling ghoul, the reanimated corpse and its insatiable appetite for human flesh, destroying the brain, it all started right there.

Romero tapped into something primal and accomplished something no one else has, he created a monster to rival the horrifying undead of yesteryear. Though Night of the Living Dead was panned by critics upon release due to its explicit nature indie production, it passed the test of time, earning zombies a place in the pantheon of monsters alongside vampires, werewolves, and mummies.

That legacy, unlike so many others, has endured. Today, nearly fifty years later, zombies are as popular as ever, due in large part to the popularity of AMC's The Walking Dead, which owes to Romero's blueprint.

Zombies have invaded the public consciousness, probably for good. It's likely that you and your friends, (perhaps around a couple of drinks) have debated the likelihood of a zombie epidemic. You've planned your survival steps, assigned roles, and imagined yourself as the sole survivor wandering a world returned to dust.

Zombies

Credit: Getty, inhauscreative

In this world of antibiotic-resistant bacteria, quick international travel, and genetic manipulation, how might zombies (or something functionally similar) actually rise up?

It's important to note from the start that crafting literal zombies, reanimated corpses, is entirely outside the realm of possibility according to a modern understanding of biology. A truly dead organism would have no way to convert food into ATP energy. It would be unable to process oxygen. The body would stiffen. The muscles would atrophy. Movement becomes impossible. Zombies, as they are portrayed in popular media are a supernatural phenomenon. But could you craft something that would cause living humans to behave in such a way as to become, for all intents and purposes, zombie-like? We'll see.

Rabies Hybrid

The closest viral equivalent to a zombie disease in the real world is the rabies virus. The disease is passed primarily through bites and symptoms in humans include: inflammation of the brain, anxiety, confusion, and agitation, followed by hallucinations, excessive salivation, aggression or violence, and inability to move parts of the body. Sound familiar?

The biggest hurdle to a larger outbreak is the inefficient transmission vector, the long incubation period, and the relatively small window of time between symptoms and death. Once acute symptoms occur, the stuff that makes a person behave like a zombie, rabies is almost always fatal after a period of two to ten days.

In order to result in an outbreak we might recognize as world ending, the disease would need to be easier to transmit, incubate more quickly, and keep the host walking and biting for a longer period of time.

Sean Hoade taught the first ever for-credit university class on zombies at the University of Alabama, wrote the book Zombie School Confidential and has spent more time than most considering how exactly zombies might make their break from the fiction into the real world. We spoke with him about how to bring about the end of the world.

"The metaphysical aspects aside, the important part about zombies, if you run into one, is they are incredibly aggressive and they're contagious. If some mad scientist somewhere were able to combine the rabies virus with the flu, you would have something like a zombie virus. Rabies makes you aggressive, it makes you want to bite. If you combine it with the flu virus then it becomes airborne and incredibly contagious," said Hoade.

It isn't uncommon for viruses to change rapidly, dodging the defenses of their victims, but the odds are in our favor that a rabies/flu hybrid won't arise naturally. The two viruses are too divergent. If changes in the influenza year after year are like Galapagos Finches developing specialized beaks, merging rabies and the flu would be like mating a sea slug with a giraffe.

Which is to say, it wouldn't be easy and would probably result in something that would be really bad at doing anything.

Hacking at the brain

A virus is only the most obvious course of action if ghouls are your goal. What we're really after is behavior and, when it comes to the human brain, there are endless ways you can tamper with the input and output.

Beneath all of that higher order function that lets us drive cars and build rocket ships, there is an angry, cantankerous reptile brain capable of operating your body without your knowledge, an underground operating system that attacks first and asks questions never.

The nature of consciousness is not something we completely understand. Among people who study the mind, explanations for the "me" inside the meat are various. Many believe consciousness is an emergent property, a coalescing narrative necessary to make sense of all the information your brain is processing.

What we know for sure is that the brain and the body are capable of taking in stimuli and reacting to it without your being aware. In fact, according research at the Max Planck Institute for Human Cognitive and Brain Sciences, conscious thought is an illusion that happens after the fact. All of the actual decision making happens underneath what we experience.

"There's this thing called blindsight. It happens when you lose part of your field of vision, maybe from a brain injury. They've done experiments and the patients will say they can't see anything but when pressed, they'll guess and most of the time they're right," Hoade said.

This research is changing the way we understand the human experience and suggests it is hypothetically possible to shut down higher level function, leaving the lower order processes up and running, even without conscious experience.

An alternative would be to hijack the physical triggers in the brain that control aggression.

As crazy as that might sound, it's been done. Researchers at Yale were able to identify the neurons in mouse brains responsible for predation behavior. Using lasers they could activate a group of neurons that would cause the mice to pursue prey. A second set of neurons, when triggered, caused the mice to attack.

This tactic, of course, has its limitations. Damaging or hacking the brain isn't contagious and would have to be intentionally accomplished on an individual basis. Still, there's something frightening about the notion of techno-zombies.

Cordyceps: a fungal invasion

Once again, nature provides terror more complete than our worst imaginings. While Romero's human zombies are (at least for the present) safely in the realm of fiction, other species aren't quite so lucky. Insects in some parts of the world have to contend with apocalyptic fungi called cordyceps, bent on taking over their minds and bodies.

There are more than 400 species of cordyceps the world over and research suggests each is specialized to a particular insect species. Fungal spores infect the insect of choice and proliferate through the body, replacing tissues until only the exoskeleton remains.

That's frightening all on its own, but it's what the fungus forces the insects to do before death that has earned them a place on this list.

Ophiocordyceps unilateralis infects Carpenter Ants in tropical forests of Thailand and Brazil. Once spores have made their way into the ant's body, they begin producing chemicals that control the ant's movements. The infected individual no longer behaves according to its natural role for the hive. Instead, it begins to serve a new master. The fungus forces the ant to convulse uncontrollably until it falls to the forest floor before climbing up to the vein of a leaf where it clamps itself in place with its mandibles.

 

No longer in control of its own body, the ant locks itself in place and dies. The spores continue to spread through the body, replacing all soft tissues. Only then does the fungus complete its reproductive cycle by sprouting fruiting bodies from the ant's head. Over the course of the next several days, the fungus grows, eventually releasing spores to repeat the process with the next victim.

The mechanism by which cordyceps accomplish this feat of biological puppeteering isn't fully understood. While it has been traditionally believed that takeover of the host is accomplished via chemicals that override brain function, recent research indicates the fungus takes over muscle function directly leaving the brain intact until the end.

Which means, if and when cordyceps make the jump from insects to humans, turning us into murderous automatons, it's possible we'll be completely aware of what we're doing and powerless to stop it.

Mass hysteria: the infection of ideas

While mad scientists the are feverishly working to combine deadly diseases into an unstoppable bio-weapon, harness the power of parasitic fungi, or craft elaborate robo-zombies, perhaps the greatest threat to our collective sanity and continued existence is already inside us.

Human beings have an incredible propensity for fulfilling the worst of our own predictions. We're all waiting for the house of cards to collapse and, by virtue of our own collective anxiety, we might just make it happen.

Fits of collective mania dot our history, from the mundane and harmless to the truly insane. In 1518 a dancing plague took over Strasbourg, part of the Holy Roman Empire located in modern day France. You read that right, a dancing plague.

Several people began dancing despite the lack of any music or a reasonable excuse to bust a move. As time went on, more and more people joined, eventually numbering in the hundreds. The dancing went on for roughly a month and people died, collapsing from exhaustion, heart attacks, and stroke.

One report from the time suggests that, at one point, around fifteen people were dying every day. Cue the pharmaceutical ad voice, "Talk to your doctor before you begin dancing. Side effects include: embarrassment, loss of friends, and in rare cases, death." Someone tell the Reverend Shaw Moore he might have been onto something.

The point is, people are susceptible to suggestion, even when that suggestion is ridiculous. To complicate the issue, one of the most common types of mass panic is epidemic hysteria, wherein people believe they have a disease when they don't. In some cases, people develop actual symptoms of a disease while having no physical biological source.

If dancing could kill people in the sixteenth century, imagine what could happen today with the benefit of instant international communication. All we need is one reasonably believable claim of zombie-like symptoms and we're done for.

"There's also another kind of zombie that we don't think about anymore. They aren't literally zombies but people get infected by social media and things that compel them to be very aggressive and, in a virtual way, spread that infection," Hoade said. "Take someone who's predisposed by these calls to aggression who then infects others."

 

The good news is zombies will likely stay where they're comfortable, on the page and screen. Provided we can all keep our heads, be kind to one another, and the dancing to a minimum, we'll probably be just fine. But someone should declare Oingo Boingo's "Dead Man's Party" a public health hazard immediately.