They Can't Take the Heat
It's generally accepted by zombie experts that they're going to continue to rot, even as they shamble around the streets. What the movies fail to convey, however, is the gruesome yet strangely hilarious effect the hot sun has on a rotting corpse.
The first concern is putrefaction
. Thanks to the plethora of bacteria we use in our colon for digesting plant matter, called gut flora
, our bodies are ripe for decay the second our heart stops. Since heat speeds the growth of bacteria (which are plenty happy to start feasting on you once your immune system is no longer a concern) the zombie's got a looming expiration date the very second it turns.
Dead bodies bloat because of the gases created by the bacteria, meaning that in warmer areas even Abercrombie Zombies are going to start getting fat in the first few days. After a few weeks of this, the nasty, bloated zombie army is going to start doing something that is simultaneously the most awesome and disturbing thing a zombie can do: they will start exploding (CAUTION! Pictures!)
. The warm, moist conditions in the tropical and subtropical parts of the world (or even just summer in the temperate parts) speeds this condition, meaning a July zombie outbreak pretty much anywhere would be over in a few weeks just by virtue of the rampaging monsters bursting like rancid meat balloons.
At the other end of the heat spectrum is dry heat. If you're in Phoenix or the Sahara when the apocalypse hits, the zombies might begin to mummify
in the blazing sun and heat. While the normal symptoms of dehydration are not a concern for a zombie, there is the problem of desiccation
. With no reasonable means of replenishing the water in their cells, zombies walking around in the Texas heat all day are going to suffer cell damage due to direct sun exposure to their skin, and thanks to the drying effect wind has, the Southwestern dead will stumble around more and more ineffectively until, at some point, they simply drop and wait for the scavengers to come pick them up for the annual Slim Jim harvest.
So they'd better hope the outbreak happens during the winter, right? Well...
I guess there are two number 6's. lol
They Can't Handle the Cold
Zombies are dead meat. No arguing that; it's their one defining characteristic. But everybody focuses on that "dead" part like it's such a huge deal. They often forget about the "meat." Do you know what else is dead meat? Steak, hamburger, possibly even that red grease mush inside of Taco Bell food.
Look at it.
When flesh is alive, it's got all sorts of defense systems to keep it that way. When it's dead, you have to throw it away in about a week even if you seal it up in plastic and keep it at a carefully modulated temperature. Now, your first inclination may be to think of cold as dead meat's friend, after all, the surest way to defeat that week-long deadline is to freeze steak, keeping it fresh for months. But don't forget: Unregulated cold does awful **** to formerly living things. If you live far enough north, the zombie apocalypse will probably work itself out the first time it tries to go outside. The first zombie-killer is the simple fact that the human body is mostly water, and water freezes. Once the temperature drops to freezing (or near it with a high wind chill), zombies will become significantly more rigid.
No word on them transforming into snow monsters.
After enough exposure, a dead body is going to be frozen solid and not chasing down any screaming victims, no matter how delicious and Rascal Scooter-bound they might be. It's also safe to assume that zombies wandering around in a wintry wonderland are not going to be wrapped air-tight in plastic like we do with food, so freezer burn becomes an issue. Seriously. The same thing that ruins your ice cream also ruins the Undead Onslaught. The freezing of the flesh at night, combined with partial thaw during warmer days, then refreezing again sets up the perfect conditions for the onset of freezer burn, which results in the cells dehydrating as water evaporates, even when frozen solid
. Freezer burned meat isn't just dead, it's destroyed.