Everyone has seen the movies: the undead rise from their graves to attack the living. Sometimes they swarm in packs and attack the weak with snapping bites, sometimes they prowl quiet city streets with their grey skin glowing in the moonlight, and sometimes they attempt to stay among the living long enough to feed their undead urges. But beyond the movie madness, you have to wonder: Is a zombie apocalypse possible?

What is a zombie?

We might like to imagine that all zombies are slow-moving, brain-dead flesh hunters, but it turns out that there are a terrifying number of different zombie species — all fictional as of now, of course. Some of the silver-screen undead can sprint at their prey, making them especially dangerous; others are only able to utilize the top half of their bodies (making them commonly known as crawlers).

But regardless of the specific zombie variety, there are some common and creepy characteristics that all of these monsters share.

Female zombie on railroad tracks
Sven Kirsch / NeedPix

First off, zombies are dead. This is what gives them that tell-tale glazed-over-eyes look, dull skin, and sagging demeanor. Additionally, all zombies, whether they can run, walk, crawl, or ask questions, are focused on one thing and one thing only: living human flesh. They love it. They crave it. They’ll do anything within their power to get it. But horrifyingly, this isn’t what we should be scared of.

Zombies don’t come by their insatiable desire for flesh naturally. These poor people only gain their cannibalistic tendencies when they are infected with a virus, usually by way of another zombie’s bite. Once infected, the zombies lose themselves to their newfound cravings: they no longer have personalities or feelings or empathy.

The only thing an infected zombie cares about is getting their hands on some living person meat, and unfortunately for those of us still living, the zombie infection is always incredibly contagious.

How possible is a zombie apocalypse, really?

Viruses are pretty terrifying, all things considered. They spread easily, can kill quickly, and have the ability to destroy entire communities without taking a break. That being said, should a real-life zombie virus take hold, we’d at least have a tiny bit of luck on our side. The zombie virus is transmitted via bodily fluids, which is why you have to be bitten by an infected body to get the infection yourself.

While bodily fluid-based viruses (like Ebola) are bad for sure, killing almost 5,000 people in big outbreaks, they’re nowhere near as deadly as airborne viruses (like influenza), which can kill nearly 300,000 people in a year.

The chances of a zombie apocalypse actually occuring the way it does in the movies is not only incredibly unlikely, it’s impossible

However, there’s good news. Because zombies are undead (AKA they’re dead bodies that have been brought back to life via the virus that gives them such flesh-eating mania), the chance for a zombie apocalypse to occur the way it does in the movies is not only incredibly unlikely, it’s impossible.

For the body to function and do all the things it needs to do (like run, eat, sleep, breathe, etc.), it has to have oxygen and blood. And what needs to be active to make that happen? The brain. Without an active and working brain, our bodies aren’t able to control our muscles, making our lungs and veins useless. So even if a dead body was injected with the zombie virus, nothing would happen, no matter how nasty the virus itself was. Good news, right? Not so fast.

What does the science say?

So on the positive side, an undead zombie crisis isn’t going to happen anytime soon. But before you start celebrating the impossible-ness of your worst fears, consider this: Some of the most well-known zombie symptoms are all too real.

A Harvard ethnobotanist (a scientist who studies plants through local cultures’ uses and traditions) stumbled upon an alarming case of zombie-ness in Haiti in the 1980s. Locals had noticed that their friends and loved ones were dying and then, much to their surprise, getting back up again and moving on with their lives as if nothing ever happened (despite some zombie-esque symptoms like numbness, nausea, and general weakness). Even though Wes Craven would go on to make a movie about the scientist’s discoveries, the explanation is a bit easier to swallow than undead taking over the world.

As long as you don’t make a habit of eating brains, you should be pretty safe.

The ethnobotanist, Wade Davis, discovered that this spate of reanimated corpses was caused by a neurotoxin, a chemical that destroys or damages nerve tissue. Luckily, the neurotoxin isn’t particularly infectious; it’s found in pufferfish and some other animals, but it’s not very transmittable. Unfortunately, though, this neurotoxin isn’t the only thing causing zombie-like behaviors.

Proteins known as prions have had their moment in the sun with outbreaks of Mad Cow disease, but they can make people zombielike, too. When people eat other people, especially their brains, they ingest prions, which cause them to lose control of their bodies and powers of speech. It’s pretty terrifying, but as long as you don’t make a habit of eating brains, you should be pretty safe.

Additionally, most of the common traits of zombies are eerily similar to real-world brain disorders. For example, lesions in certain parts of the brain can cause the garbled speech of zombies, and damage to other parts of the brain can cause people to have uncontrollable appetites.

What can you do to prepare yourself for zombies today?

Interesting fact: even though the likelihood of a true zombie apocalypse is nil, the CDC has still published a guide to surviving the zombie apocalypse. Sure, it may be pretty silly, and zombies aren’t going to be pounding at your door anytime soon, but better to be prepared and fight off the nightmare than to open the door to disaster, right?

First off, create an emergency preparedness kit. Make sure you have all of the following items ready to use in your home should you be stranded inside for a while (whether it’s because of the hordes of zombies or something a bit more natural, like a flood or a blizzard).

  • Water (bottled, just in case your water source is tainted or turned off)
  • Food (non-perishable food that you’ll actually eat, not just a shelf full of old beets)
  • Medication (pain meds, stomach settlers, and any prescriptions)
  • Handyman tools (duct tape, hammer and nails, probably a radio, etc.)
  • First aid (bandaids, gauze)
  • Clothes and blankets
  • Identification for everyone in your family

 

After you have your emergency kit ready, make a plan. If zombies (or tornadoes or earthquakes) do attack, what will your family do? How long can you stay safe in your home, and where will you meet out in the world if you’re not all together when it hits? Who do you need to contact (family, friends) to make sure they’re safe? Where and how will you get up-to-date information about the rest of the world?

Chances are good that you’ll never have to deal with an actual zombie crisis, aside from the kid waking up with zombie nightmares in the middle of the night. But it’s never a bad idea to be prepared for disaster, so let zombies be the fictional inspiration you need to build a preparedness kit, make a plan, and stay safe from whatever is out there.

A deeper dive — Related reading from the 101:

Some animals are already facing their own zombie apocalypses. Make sure they can’t spread it to you!

Mammals aren’t the only ones who should be afraid of the zombie apocalypse.