You know how when you have the urge to smack someone and you connect with one perfect blow it feels really good? Turns out there's a biological reason for that.

While you probably know sex, food and drugs stimulate the pleasure centers in our brains, a new study from Vanderbilt University finds that aggressive behavior triggers the release of chemicals like dopamine that make us feel good.

"Aggression occurs among virtually all vertebrates and is necessary to get and keep important resources such as mates, territory and food," Craig Kennedy, professor of special education and pediatrics, is quoted as saying. "We have found that the 'reward pathway' in the brain becomes engaged in response to an aggressive event and that dopamine is involved."

By "reward pathway," he means that every time we bang someone up, the feeling we get from it makes us want to bang people up more. The study showed that people will intentionally seek out an aggressive encounter because it gives them pleasure.