Since zombies are not fully dead, they upset the essential balance of nature: no animals eat zombies, apparently, and zombies do not seem to decay, at least, not to the point of disintegration and reintegration back into the soil, so the food chain, or the circle of life, seems to end or be short-circuited by their existence. Zombies fulfill the worst potentialities of humans to create a hellish kingdom on earth of endless, sterile repetition and boredom.

Zombies are then a symbol of our own mad urges to destroy ourselves, and a terrifying portent that we might succeed.

The zombie threat is made worse by the fact that their victims then turn into the creature that attacked them. This too is similar to other monsters (werewolves and vampires) and also similar to the sub-genre of infection/plague films. In the case of zombies, however, this may carry a greater sense of dread and revulsion: vampires and werewolves can be seen as desirable, potent, intelligent, virile creatures whom one might like -- in some way at least -- to become; a mindless ghoul condemned to wander aimlessly across an empty, ruined earth seems much less attractive.

Since zombies are not fully dead, they upset the essential balance of nature: no animals eat zombies, apparently, and zombies do not seem to decay, at least, not to the point of disintegration and reintegration back into the soil, so the food chain, or the circle of life, seems to end or be short-circuited by their existence. Zombies fulfill the worst potentialities of humans to create a hellish kingdom on earth of endless, sterile repetition and boredom.