Halloween is a popular time for zombie activity, but even when the pumpkins are gone and the witch costumes are put away, the zombies will keep on marching.
That's because the living dead are a year-round affair these days, and not just in movies. Around the world, a growing number of people are dressing up as zombies for parties, festivals, walks and pub-crawls in every season.
To explain the undying boom in all things zombie, experts point to the versatility of zombies as a metaphor. Compared to vampires or werewolves, zombies can symbolize everything people are afraid of and anything that seems to be tearing society apart. Over the decades, the undead have addressed race relations, class wars, diseases, mindless consumerism and more.
"Part of what I really like about zombies is that they don't always represent the same thing," said Brendan Riley, a media scholar at Columbia College Chicago. "They're a really flexible storytelling tool for describing all sorts of different cultural and societal problems."
First-generation zombies emerged from voodoo culture in Haiti more than 100 years ago, argue some academics, including Nick Pearce, a sociologist and anthropologist at the University in Durham in the United Kingdom. Surrounded by a variety of merging African cultures and religions, Haitians believed that sorcerers could put curses on dead people, bringing them partially back to life for use as slaves.
Zombie sightings were documented in Haiti, and although there are possible medical and pharmacological explanations for what was happening, plenty of Haitians were convinced that zombification was indeed possible. No one was actually afraid of zombies themselves, Pearce said. Instead, they were afraid of being turned into zombies.
Not long after the United States began to occupy Haiti, a 1929 novel called The Magic Island introduced the concept of zombies to Americans, and Hollywood immediately jumped on the image. The first zombie film, called "White Zombie," came out in 1932.
At first, American zombie films echoed Haitian themes. The movies took place in tropical settings. And there was always an evil character that, much like a voodoo sorcerer, controlled the zombies as they did terrible things.
Those earliest zombies, Riley said, were clearly a metaphor for the fear that a minority of whites had of an uprising by poor blacks, who made up the vast majority of Haiti. By the 1960s, though, zombies started to address other concerns. With race riots, the Vietnam War and protests going on, zombies could represent fears that the world was being irrevocably ripped apart.
Not all zombie aficionados agree that today's zombies emerged from the Haitian versions.
"From a factual, anthropological, religious or historic standpoint, there is no connection between the voodoo zombie and the modern zombie," said Matt Mogk, founder and head researcher at the Zombie Research Society. "Academics who view the topic from their narrow field of expertise often make the mistake of combining the two."
Regardless of their true origins, the premier of "The Night of the Living Dead" in 1968 marked a turning point for zombies. Not only was the cult film subversively critical of government, race and societal norms, it took zombies out of their usual setting. Instead of the tropics, the ghoulish characters were now walking around central Pennsylvania.
Even more significant, the zombies were no longer being controlled by an evil leader, said Pearce, who will be giving a talk on Wednesday about what zombies can reveal about society at the Economic and Social Research Council's Festival of Social Science.
In a succession of horror films, zombies evolved into scary figures independent of a larger power. So today, we may still fear becoming a modern form of mindless zombie, glued to our smart phones as we walk through shopping malls. But we are also afraid of what other zombies will do to us.
"Today, the idea is not that we are being controlled by a menace, but that everyone everywhere is a mindless zombie, and there is no one target to actually blame anymore," Pearce said. "Maybe zombies should occupy Wall Street."
Despite their gruesome looks and frightening symbolism, zombies have also become a form of fun. More than 6,400 people "like" the Zombie Pub Crawl Facebook page, which organizes thousands of people in a drinking, dancing event through the streets of Minneapolis for one night each October. The event, which is the largest out of a list of dozens like it around the world, has grown exponentially since 150 people showed up for the first one in 2005.
By dressing up and acting like zombies together in events like these, people may gain strength as they acknowledge their powerlessness, Pearce said. Or, as Mogk argued, they might just enjoy belonging to a group that doesn't reject anyone.
"At zombies walks, you see university professors walking next to young families with kids walking next to a tattooed punk rocker with a mohawk who they would usually cross the street to avoid," Mogk said. "Zombies are your friends in low places. Everybody is welcome to join their club."