zombieI love to watch everything I can about zombies… movies; TV shows; books; stories; and video games.

I realize they are purely fiction and for entertainment purposes only, but occasionally have to have a bit of a debate when people say to me, “You know, it could really happen.” As awesome as a undead zombie apocalypse might be, it simply can’t happen. And if it did, there isn’t much of a reason to worry.

Before we discuss why zombies are not really a threat, we must define the zombie type we’d be confronting in this version of the zombie apocalypse. I’m going to take the classic undead zombie with the following characteristics:

  • Semi-decayed, rotten body
  • “Hungry” for human brains and flesh
  • Shuffles, walks, or runs (depending on state of their limbs). For the sake of this argument, movement speed doesn’t really matter.
  • Their brain allows for basic functions only: hunt for food, kill enemies, stay “alive” (er, undead).
  • They only know one word: “brraaaaaiiiins…..”

We’re talking Night of the Living Dead, not 28 Days Later.

Here’s Why We Don’t Need to Worry About A Zombie Apocalypse.

1. Unlike living things, zombies can’t heal

Over the days, weeks, months… zombies would take damage from humans and other predators. But since they’re reduced to a rotting corpse, they could not heal or regenerate. As muscle tissue was damaged, limbs would be rendered useless. Imagine a zombie with a slashed bicep muscle… he won’t be able to do any curls at the gym since the physical structure/mechanism of his arm is permanently damaged.

Speaking of predators…

2. Zombies have lots of predators

Predators like dogs, raccoons, lions, tigers, ligers, vultures, and maggots. There are many scavengers who would take full advantage of a slow moving, smell-from-a-mile-away, piece of meat. Imagine a zombie walking through the forest? How far do you think he’d get before being nibbled away by The Racoons?

3. In the winter, they’d freeze

Once the temperature hits zero degrees Celsius, they’d be in serious trouble. Since they’d have no mechanism to regulate their body heat, zombies would go stone cold like a Swanson Hungry Man frozen dinner in the freezer. The Canadians and Russians would surely have an advantage against the undead armies of the north.

And in the south…

4. In the summer, they’d rot really quickly

In fact, the moist wet areas of the zombies would rot the quickest. But pretty much every zombie I’ve seen in the movies still has regular looking eyes even though they might be missing the lower half of their body. Depending on the surrounding conditions – like temperature and humidity – a body can decompose in a matter of days.

As a side note… the dramatic blood-exploding head shots that movies portray wouldn’t occur since there would be no circulation of blood… gravity would take its course, filling the lower parts of the body. So a head-shot would simply go through the head and splatter whatever matter has not yet been liquefied.

rotting zombie w eyes

5. Humans have lots and lots of weapons… and they know how to use them pretty well

In fact, in the USA alone, there are over 14 million gun owners. That’s a lot of guns. Plus, there’s this thing called the “military”, which has even more guns and ammo, and a ton of people who know how to use them. If the USA could get Bin Laden, I’ve got to have some faith that they can take out zombies.

6. Most importantly, if only the brain stem (or lower brain) is working, then zombies would have no senses (literally)

Several zombie “explanations” use the idea that the zombies have only base functionality in their brain. That is, the lower brain (or brain stem), is the only part that is functioning (in the TV series The Walking Dead, this explanation is used). But there would be a few problems if this were the case.

Mike Palige, from New York University, takes a look at this from a neuro-scientific approach. If we assume that only the brain stem is working then zombies…

• Shouldn’t be able to move… If only the lower portion of the brain is active, then the part that is not active is the motor cortex, which controls movement… and if that’s dead – then how could zombies walk or run?

• Shouldn’t be able to see… If the sensory processing areas of the brain are dead, then how can zombies see? Sight is processed in the occipital lobe in the back of the brain. If that area is dead, then they should be completely blind.

• Shouldn’t be able to hear… Sound is processed in the temporal lobe of the brain – so that needs to be functioning as well for them to hear you.

• Shouldn’t be able to smell… In some instances, zombies can smell… but smell is processed by the olfactory nerve above the nasal cavities, which would also be shut down.

• Shouldn’t have a memory… If zombies have some form of memory then the frontal cortex – which does higher level thinking – then that would also have to functioning.

walking dead, brain deadSo in order to have any use of their senses, almost the entire brain must have some sort of function. And for that to happen, the brain needs oxygen and energy to feed the chemical reactions required to process pretty much anything… which means you still need working lungs, heart, circulatory system… So “Sally” the zombie, missing half her body, would not be able to do much of anything. She couldn’t even be a zombie – only dead.


28 days later, zombie in window

Continue to suspend your disbelief and enjoy your zombie entertainment! You don’t have to worry about undead decaying zombies because they can’t really do anything other than lay on the ground and play dead.

However, watch out for the zombies of 28 Days Later… ‘cause they ain’t really dead – just really, really angry…

Update: May 20th, 2011

The Center for Disease Control (CDC) has published a blog post entitled Preparedness 101: Zombie Apocalypse. Do they know something we we don’t? …. No, they’re just having fun. In any case, it’s definitely worth the read.

  • Anonymous

    One thing you have missed, even if zombies happen the government would probably deploy quarantine procedures (i.e. deploying a nuclear weapon(s)) especially in crowded areas such as a major city to prevent the spread of the affliction. I would be more worried about nuclear winter than zombies at that point.

  • ThatManAgain

    The people who say “You know, it could really happen.” Should go to the Doctors to see if only their brain stem is functioning and the rest of their brain has dried up.

  • Guillermo Díaz

    So, the only thing we need to worry about is Crossed type zombies…

  • an0nym0us

    so only Genetic modification types can relay happen like in 28 days later or resident evil.

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