It happens in military units, street gangs and even among athletes on sports teams. In some cultures, the rituals mark the transition from adolescence to adulthood. And in fraternities and sororities, it's practically a given.

With a long history of seemingly universal acceptance, the practice of hazing is an enduring anthropological puzzle. Why have so many cultures incorporated it into their group behavior? Aldo Cimino, a lecturer in the Department of Anthropology at UC Santa Barbara, seeks to answer that question. His work is highlighted in the online edition of the journal Evolution and Human Behavior.

"Hazing exists in radically different cultures around the world, and the ethnographic record is replete with examples of initiation rites that include hazing," said Cimino. "It is a practice that cultures continually rediscover and invest themselves in. The primary goal of my research is to understand why."

One hypothesis Cimino is exploring involves evolved psychology. "The human mind may be designed to respond to new group members in a variety of ways, and one of those ways may be something other than a hug," he said. "I'm not claiming that hazing is inevitable in human life, that everyone will haze, or that nothing will reduce hazing. But I am suggesting that the persistence of hazing across different social, demographic and ecological environments suggests that our shared, evolved psychology may be playing a role."

Hazing and bullying have a lot in common -- individuals who possess some kind of power abuse those who don't -- but what makes hazing strange, according to Cimino, is that it's directed at future allies. "It's very rare for bullies to say, 'I'm going to bully you for three months, but after that we're going to be bros,' but that's the sort of thing that happens with hazing."

Cimino suggested that in some human ancestral environments, aspects of hazing might have served to protect veteran members from threats posed by newcomers. "It's almost as though the period of time around group entry was deeply problematic," he said. "This may have been a time during which coalitions were exploited by newcomers. Our intuitions about how to treat newcomers may reflect this regularity of the past. Abusing newcomers -- hazing -- may have served to temporarily alter their behavior, as well as select out uncommitted newcomers when membership was non-obligatory."

Cimino performed a study on a representative sample of the United States, in which participants imagined themselves as members of hypothetical organizations. Organizations that participants believed had numerous benefits for newcomers (e.g., status, protection) were also those that inspired more hazing. "In my research I've found that group benefits that could quickly accrue for newcomers -- automatic benefits -- predict people's desire to haze," he said.

"This isn't the only variable that matters -- there's some effect of age and sex, for example -- but the effect of automatic benefits suggests that potential vectors of group exploitation alter people's treatment of newcomers in predictable ways," Cimino continued.

He cautioned that scientists are a long way from understanding hazing completely. "Hazing is a complex phenomenon that has more than one cause, so it would be a mistake to believe that I have solved the puzzle. However, every study brings us a little closer to understanding a phenomenon that seems increasingly visible and important," he said.