The zombies struck a chord of dissonance in my mind. They were unlike the other monsters I had known. The zombie obeys no rules for one -- no fear of God, full moon, silver bullets, garlic. My young Catholic-trained mind couldn't reconcile that zombies didn't fear a cross or a church. They were manmade and the byproduct of a radiation, an obvious code word for nuclear war.
My subconscious reasoned thusly: if radiation creates zombies and I don't understand radiation then there is no known reason not to believe a zombie is possible. So I rode my bike home extra fast, planning my zombie-avoidance and defense strategy in case my suburban neighbors become infected.
I feared my neighbors. Civilization was a threat.
In the original Night of the Living Dead (1968), the hero is a black man named Ben. Ben is the only capable character, and the only character who isn't paralyzed with fear or paranoia. But his entire life has been the night of dead. The masses have passed laws against him and actively tried to destroy him. His entire life has been training for the night of the living dead. He's shot dead by the white militiamen at the end of the movie, "mistaken" for a zombie. The viewer is left to construct what would have happened had he not been murdered. Would he be allowed to join the militia? How would the militiamen respond to a sole black survivor?
I'm a big fan of Civilization and Its Discontents. The premise is the dichotomy between the individual's desire for freedom and civilization's desire for order. The individual surrenders freedom in exchange for civilization's benefit -- a 9 to 5 for not dying during childbirth. The zombie apocalypse represents the collapse of the individual and civilization contract. Civilization turns against its members. The rescue message from Dawn of the Dead is obvious: ALIVE INSIDE painted on the roof of a mall and symbolizing the individual's struggle against civilization. The survivors grotesquely resume their former lives in the comfort of consumerism. But the zombies are attracted to the mall as well, drawn by the shadows of their former existence. We feel we are the ones who are alive inside and the others are the zombies.
Another film to mention is REC (the Spanish version). The outbreak in REC seems to be caused by a possession rather than a scientifically knowable fact. REC also takes place in a quarantine, rather than civilization as a whole. The characters are pitted against each other and the undead. REC is a good scary zombie movie, but lacks the overt social commentary of american zombie movies.