There are a lot of different explanations for what makes a zombie in movies and books; everything from voodoo to radiation can cause an outbreak it seems.
One of my particular favorites is parasites. Mostly because it makes the most sense in believable sense. In this case, the “zombies” aren’t really dead, they are simply behaving according to how the embedded parasite is forcing them to act. It seems far fetched no matter how you spin it but it is the only sort of zombieism that can be found abundantly in nature.
So for all you science and zombie lovers here is a quick video showing how DISGUSTING and horrible these parasites can be. (But if you are at all like me you’ll also see real beauty in how nature works. It’s amazing really.)