Our movie is going to open with something pleasant. Quiet. Unassuming. Cillian Murphy having a nap, Barbara and her annoying brother going for a drive, Milla Jovovich dressed in mildly inappropriate fashion not conducive to fighting dogs that seem to be inexplicably wrapped in bacon. And then pretty soon a zombie is going to run out of nowhere all "bwaaggh blarr gwaaah" and try to eat someone's head and it's all downhill from there for our hero as he or she assembles a few survivors who slowly dwindle down to a couple of people by the end as everyone else is torn asunder and zombified. It's so much like a road trip to Detroit, you have no idea.

The biggest problem in the zombie world for you, a non-zombie, is becoming a zombie. You don't want that. It probably sucks horribly. How often do you think zombies have sex? Never. Not ever. Because their bits and bobs are rotten and ill-suited to the task. That sucks. So you want to avoid zombies. The downside, of course, is that zombies want to eat you, right? But do they?

We take it for granted in the genre now that some things are generally standard. Zombies are reanimated corpses. They lack the mental faculties of a living person and are driven only by base hunger, like customers at an Arby's, willing to eat anything. But if all they want to do is eat you, why are there so many zombies around?

You never see half-eaten zombies in movies. Sure, you'll see the odd legless zombie, like that cool one in the first season of The Walking Dead that Rick puts out of its misery instead of mounting it on the hood of his car like the most badass hood ornament in the history of ever, but why are so many fully intact, barring the odd trauma and pasty, creeper eyes? If zombies are eating people, shouldn't heavily populated areas be littered with stripped-bare corpses? Dirty, gnawed skeletons all over the place and such? That would make sense, especially in densely populated areas like cities. For every abandoned car burning on the side of the road, there should at least be one body eaten down to stubs and giblets. Instead, zombies seem to attack people, have a nibble, and then like disinterested partygoers faced with a crappy hors d'oeuvre platter, they move on. If you're that hungry, eat your damn meal, you dirty zombie. But they never do. Why is that?

Some have argued, and a few films bear it out, that what separates food from zombie brother is stank. In Shaun of the Dead, they went so far as to suggest that just acting like a zombie is pretty decent cover for getting past them. So if something prohibits a zombie from eating his own stinky, limping brethren, there's still a world just lousy with house cats, cows, lemurs and Kardashians. Why can't those be eaten? I like to think that if I were a zombie, I'd just head to Costco and spend the rest of my wretched existence eating giant tubs of mayonnaise and goldfish crackers. Who has time to chase down svelte, young action heroes? Plus suppose you even catch Emma Stone, who seems awesome and all, but I bet she tastes way shittier than some Manwich. Why bother?

Suspension of disbelief works best if the suspension is not stretched to its utmost limits. In a fairy tale setting, anything goes, and we as an audience are OK with it because the world is pure fantasy and if you want to introduce a talking penis that grants wishes, that's legit. In zombie fiction, you're suggesting that this is happening in the real world. The world this article exists in, the world you exist in, the world Gary Busey exists in. It has rules. Our suspension of disbelief is that something is animating dead tissue. Cool. Let's toss in a zombie cheerleader.

Knowing that a zombie is just a corpse that keeps moving presents a whole sticky wicket of problems. Did I use that term correctly? No. It's just as incorrect as zombies chasing you down a street. Even if whatever it is that animates zombies keeps their muscles from totally atrophying or desiccating or snapping like the elastic in the waistband of my vintage 1985 Transformers boxers, how are they tracking you? The go-to special effect for a zombie is white contacts -- zombie movies love those milky white eyes, so you have no doubt that every zombie has a wicked case of cataracts. They shouldn't be able to see you dancing the Charleston down Main Street with nipple tassels and a feather duster up your ass. You guys do that to the blind, too, right?

How is that zombie tracking down its prey? Its hearing and sense of smell have to be just as bad as its eyesight, and since many movies seem to indicate a progression of their decay, it's only going to get worse with time. Eventually, they're just going to be bitey little dried-up sacks of dusty stink that can't do anything, aren't they?

On one level, I understand film's reluctance to include this explanation on camera. After all, how many episodes of 24 included a 10-minute scene of Kiefer Sutherland on the crapper anyway, just pensively staring at his hands, wishing his unreliable insides would cut him some slack so he could go defuse a nuclear president, or whatever it was he did on that show? You try to avoid poop scenes because, in the words of Hitchcock, they're f*****g silly. Weren't expecting that, were you? Neither was the cast of Vertigo.

A zombie movie doesn't need to completely devolve into a poop joke to take a moment to account for the simple problem of zombie biology. If they consume flesh, it needs to go somewhere; it's the same deal when I eat Taco Bell. It really is. World War Z made reference to their stomachs exploding, if I recall correctly, but no one on camera has addressed it. At some point, all that tasty man souffle is going to go somewhere, and it's not going to be pleasant. Not at all. Incidentally, I immediately regret the use of "souffle" in that metaphor, as it makes it sound far more sexual than I intended. You'll probably now wonder why I didn't bother to change it.

Why is this question important? Am I a fecalphiliac? Do I have an obsession with butts? This isn't about me, but I will accept butt photos and/or detailed descriptions if you have them handy. It's about a fictional world in which the primary danger to the very existence of humans as a species is a thing that uses eating as its chief weapon. There should be a stunning amount of zombie poop all over the world.

I'll concede to start with that not every zombie flick even wants to address this. But some do, and they leave a big question hanging in the air. The Walking Dead has brought this up a number of times, and of course it was a big part of the not-quite-zombie movies 28 Days/Weeks Later. Can you cure a zombie?

Certainly it's reasonable to assume you'd want to get rid of whatever it is that makes zombies, but after someone dies, and is rotting, and has eaten people, and maybe has been shot a few times, and is missing a foot, and has no skin on its torso, what is it exactly you think might be getting cured? How did the zombie apocalypse instill so much new faith in medical science in you?

As far as I know, right now, you could still potentially die from dysentery in many parts of the world. If medical science has not progressed to the point where we can prevent people around the globe from dying of pooping too much, how likely do you think it is that there's a doctor somewhere who just perfected a treatment for having half a head and trailing flaming intestines behind you? Imagine waking up in a hospital after months of being a zombie and eating people and being rotten only to be told you'd been a zombie since last year and you sort of don't have a leg now and you ate a football team. Why would you want to do that to someone?

If I were to make up a number off the top of my head, and I will because I'm numerically bold, I would say that about two-thirds of zombie movies don't take the time to explain zombies. That's not a mistake, it's kind of a zombie trope. George Romero purposely ignored the cause of the zombie phenomenon, and really, it was unnecessary when you think about it. If you were being attacked by zombies, you probably would be less concerned with why they exist and more concerned with ensuring that the last thing you see isn't your neighbor chewing off your genitals.

So, very often, the beginning of a zombie story is unwritten, and that's cool, because it's not always relevant. But no one has ever finished a zombie story. This is potentially due to the fact that it would be a curious mix of horribly uninteresting and horribly depressing if it did happen, but it's still a worthy thing to wonder about. Hell, George Romero has spanned four movies (more if you count things like Diary of the Dead, which you shouldn't) and decades of time and still hasn't gotten to the logical conclusion of all zombie fiction -- the end of humanity. If zombies kill everyone, then what happens?

Land of the Dead was just ridiculous, and the best it could offer up was walled-up cities and the decrepit countryside full of undead people in costumes and one ridiculously crafty zombie gas station attendant. But if there was a World of the Dead to follow it up, would it literally just be zombies standing there? Is that the end result of the zombie apocalypse? That's the worst end of the world ever -- a planet of guys loitering around drooling black stuff on themselves and occasionally moaning at the breeze.

For more from Ian, check out 7 Safety Products (for the Incredibly Paranoid) and 10 Retarded Money Saving Tips (People Are Actually Trying).