Zombies: Why, How Many and What Happens After the Humans are Gone?

Our culture really fetishizes the undead. Whether it’s Twilight, Left 4 Dead or World War Z, we’re really into vampires and zombies (is there no love left for ghouls, ghasts and liches?). There’s a kind of nerdy obsession, for example, with planning detailed zombie survival plans.

I was musing on the subject of zombies this morning, and found myself asking three basic questions. The first is “why do zombies actually attack humans?” Let’s assume for the moment that we’re talking about your traditional shambling undead, not the high-functioning ones in I am Legend or the sprinting, rabid humans in 28 Days Later). What is their instinctive, shambling purpose?

• To convert their victims to zombies
• To eat their victims’ brains
• To eat their victims entirely
• To kill their victims

I posed this question on Twitter, and received a variety of informed answers. A few favourites:

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Avi is actually quoting a charming song in the key of zombie by geek troubadour Jonathan Coulton.

If Rosemary’s answer of “brains” is true, then that presents a problem. It’s kind of an anti-Darwinism in action. If a zombie eats a victim’s brain, then the victim does not become a zombie. Because, as many horror movies have taught us, you have to aim for the head to kill a zombie.

And why do zombies actually eat, anyway? Do their digestive systems work, even though their other organs do not? In a conversation on Facebook, somebody suggested that “zombies need live flesh because their own is dead”. That seems like a reasonable theory.

Counting the Converted

This led to the second question, “what percentage of humans gets turned in a zombie attack?” Presumably any human that’s bitten with an intact brain gets reanimated as a zombie. Assuming that most victims’ brains are eaten, then it might be a relatively small fraction of the population. Maybe, 20%?

Then there’s the ghoulish question of partially-eaten victims. As somebody wrote on Facebook (he can claim his quote if he likes, whatever happens on Facebook and so forth):

They may not have much of a body left, they may not be able to walk, stagger, shamble, crawl, etc. but they would still be a zombie. Please don’t discriminate against the living dead on the basis of their ability to move and/or infect others. Zombie heads are zombies too!

As a final data point, somebody sent me this quote from I am Legend:

Six billion people on Earth when the infection hit. KV had a ninety-percent kill rate, that’s five point four billion people dead. Crashed and bled out. Dead. Less than one-percent immunity. That left twelve million healthy people, like you, me, and Ethan. The other five hundred and eighty-eight million turned into your dark seekers, and then they got hungry and they killed and fed on everybody.

In short, the fraction of turned victims remains an open question. Of course, some think I shouldn’t be delving into these mysteries:

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@dbarefoot Why do you bother with such frivolity? We don’t yet have the tools to begin to understand the zombie way. Accept it.less than a minute ago via TweetDeckLee LeFever
leelefever

What Happens After the Humans are All Dead?

In a serious zombie invasion, surely whole cities get entirely stripped of humans. Having no more victims, what do the zombies actually do? Do they randomly wander around? Stand in one place? Gather in a kind of impotent swarm? Rot into nothingness?

If they’re more or less brainless, and do wander randomly, then surely many of them would walk into the ocean, off a bridge and so forth. There’d be a lot of stupid zombie attrition. What do you think happens to victimless zombies?