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An Expert Explains The 'Walking Dead' Timeline Of Zombie Decay

Some of these zombies should definitely be skeletons by now.

When it comes to the gory reality of its titular zombies, "The Walking Dead" isn't exactly shy about letting it all hang out.

And by "it," obviously, we mean "human entrails in varying states of decay."

As time keeps passing in the "Walking Dead" universe, the zombies seem to be getting grosser, gooier, and much less resilient when it comes to keeping their skin on. But as the show raises the bar on zombie gore, is it also keeping true to the timeline on which human bodies actually decompose?

MTV News spoke with Kimberlee Moran, a forensic archaeologist and Assistant Program Director of Arcadia University's Forensic Science master's program, to find out the answer.

Spoiler alert: It's complicated.

From newly deceased to walking dead

MTV News: Assuming we suspend disbelief, and accept that these bodies are walking around while dead, what is the basic timeline for a human body to decay?

Kimberlee Moran: That depends a lot on the environmental conditions where the zombie finds himself. But the first thing that happens is the eyes go dull, and they decompose quite quickly.

MTV: So if the show is taking place over a period of months or years...

Moran: After nine months, depending on the environment, there wouldn't be eyes anymore.They're basically big sacs of fluid, so they're the first things to go. And within 24 hours, decomposition begins. It starts with a discoloration in the lower abdomen, and within three days the entire body is showing signs of decay. The initial stages happen quite quickly.

MTV: So most zombies who have these cloudy, creepy eyes, actually shouldn't have eyes at all.

Moran: Right. Another thing that's unrealistic about zombies is that our bodies are subject to rigor mortis. Within three to six hours of death, all the muscles in your body release lactic acid. You go completely rigid, it's like a full-body cramp. It dissipates within a few days, so then your zombie could move around again, but immediately after death you wouldn't be able to move at all.

In short: Milton should have been too immobilized by lactic acid to get up and bite Andrea, but those cloudy eyes are dead on.

From rigor mortis to soft and squishy

MTV: Based on the timeline of "The Walking Dead," many of these zombies have been dead for weeks, months, or even more than a year in cases where they've been locked indoors since the world ended. Where should they be in terms of decomposition after a few weeks?

Moran: Your gut is full of microbes, and that's what starts the process of internal decomposition. Also, your cells themselves are starting to break down. So everything soft and squishy besides your bones is basically liquefying, starting with the internal organs. They go fast. After that, the skin sloughs off. It's called skin slippage, where the epidermis detaches from the underlying tissue and just kind of slides off. But that's after the organs are fully mush, and all the bacteria are starting to migrate throughout the body.

MTV: So in between death and skin slippage, the body basically becomes a meat sack full of liquid?

Moran: Pretty much. And the body is going to be leaking out of all its various orifices. All that bacteria is producing gas, the same way it does when you're alive and you've eaten a greasy takeout meal. But when you're dead, you can't release it, so the body bloats until it gets to the point where it cant hold any more, and then all that gas and associated liquid comes out all the orifices. Dead bodies are pretty slimy.

In short: The way the walkers explode when someone hits them with a car? Not necessarily inaccurate. And this zombie must have just hit the "skin slippage" stage when Tara had the bad luck to wrestle with it.

Destination: Skeleton

MTV: So, assuming the walking dead are decaying the way a normal body would, should they eventually become a pile of bones with nothing to hold them together?

Moran: Yes. Basically, the walking dead would have all kinds of parts of their body dropping off of them all the time, until they become a skeleton. The ligaments and tendons take longer, because they're more cartilagenous, but your bones are the only part of your body that's going to last. And depending on environmental factors, it might be between one and three years before your body is totally skeletonized.

MTV: Speaking of the environment, it's worth noting that this show takes place in Georgia.

Moran: In that case, they'll go fast. If it's hot and humid like that, and the middle of the summer, those bodies can be fully decomposed within nine months.

In short: With more than 500 days passed since the end of the world as we know it, any giant herds of dead that date back to day one of the zombie apocalypse should be much, much bonier (and in no condition to participate in a parade.)

The curious case of the missing maggots

MTV: We've been talking about the internal process of decomposition, but since so many of these zombies are outside, wouldn't there also realistically be external factors affecting how they decay?

Moran: Yes! Honestly, how come the walking dead aren't completely covered in maggots? Within 24 hours of death every fly in the neighborhood would sense that there's a free meal walking around, and they would be covered in fly eggs -- and in Georgia, where it's hot, they would hatch very quickly, and be covered in maggots.

MTV: What a missed opportunity to make the zombies even more disgusting.

Moran: It's what would happen in real life. Flies can detect even very recently deceased remains from distances of over five miles.

In short: The next time you're toasting the terrific gore on "The Walking Dead," pour one out for the maggots.

Conclusion: Scientifically speaking, the walking dead are a walking paradox

Moran: Talking about this in realistic terms is hard, because we are talking about actual dead people walking around. But there's no way the walking dead could walk without some kind of electrical activity going on in the brain. The entire body is controlled by electrical impulses. That's what's going on in your brain when neurons are firing, and what runs through your nervous system to get you to actually move.

MTV: And in the context of the show, you do have reanimation occurring just in the brain stem, so that might cover basic locomotion--

Moran: Yes.

MTV: --But they're also biting people.

Moran: And that requires slightly higher level thought, beyond just being able to move.

MTV: And they don't just bite, they also eat, which makes things that much more complicated. I mean, if they're eating, are they also...

Moran: Pooping?

MTV: You know what, let's actually not talk about this.

In short: The same energy that controls voluntary movement also controls the involuntary systems that allow a body to heal and rebuild, which means that nobody should actually be able to decompose and move at the same time... and also means that absolutely none of these zombies should be wearing clean pants.