Considering all the other things we've been told to be afraid of in the past few months (taco trucks on every corner, for instance), we could be at risk of forgetting one of the most popular fictional threats to humanity: zombies. Yes, all right, they're not exactly real, but that hasn't stopped science from getting interested in them. They're not just being macabre; there's more to the science behind zombie apocalypses than you might initially think.
For one, the idea of "spread" of diseases, zombie viruses or not, is pretty scientifically important, because epidemics can kill thousands with or without flesh-eating. For another, zombie-like traits already exist in nature, and have offered a lot of interesting, faintly skin-creeping knowledge to science, raising the possibility that zombification is, while intensely unlikely, not impossible. If zombies ever do emerge, we may be able to have effective models for dealing with them, thanks to research efforts.
Scientists have looked at every aspect of the zombie problem, because priorities. How fast would a zombie apocalypse spread through a city? How could you concoct a zombie virus from scratch? Is it better to run away from a zombie or stay and hit them on the head with a spade? (I'm sure we don't need science to tell us that the correct response is to run like hell.) The result is a quite considerable amount of actual zombie-focused study, which you can add into your zombie apocalypse plan (yes, I know you have one). A lot of it is designed to demonstrate other principles about illnesses, mathematics, or biology, but who cares about that when we have an impending apocalypse on our hands? Knowledge is power, and power is knowing that a zombie virus can take over three million people in an urban area in two months.
Mathematicians Have Modeled What The Spread Of Zombification Would Look Like
Different fictional versions of zombie lore dictate its spread via different means. One is that it's spread by transmission of bodily fluids (i.e. by biting); another is that it's airborne like the flu, though that's rarer. Surprisingly enough, mathematical models of both kinds of zombie transmission through the population actually exist, because zombie infection can stand in pretty effectively for other diseases.
Zombie-Like Parasites Already Exist In Nature
There are several examples in nature of parasites that take over the bodies of hosts and significantly alter their behavior and habits to benefit the nasty little creepy-crawly now resident in their brain. It's not a mindless cannibalistic horde, but it's as close as current science comes, and it's not very pretty.
We Know What A Zombie-Like Illness Might Be Like
Somewhat terrifyingly, part of the international effort against biological warfare includes a knowledge of the possibility that somebody, somewhere, might try to zombify people. And, as Popular Science explained back in 2011, they might have a few ways to do it, though it'd likely be tricky. One option would be prions, the agents behind neurodegenerative diseases like mad cow disease, which could give people significant brain damage while still allowing them to move around; but it'd have to be artificially engineered to give the desired effect. It's also been suggested that rabies could approximate some of the symptoms of zombie-dom; but science has actually got a more specific model up its sleeve, if anybody should choose to work with it.