http://healthland.time.com/2013/05/09/the-laughing-brain/?iid=hl-main-lead

Panksepp is also intrigued by how laughter echoes throughout both higher cognitive and more primitive emotional brain regions and how the antisocial side of laughter is actually more complex. “The primal laughter [and] joy generators of the brain are in very low [less evolved] regions,” which represents their earlier evolution, he says, “but such primal forces of the mind can developmentally mature in many different directions in upper brain regions.”

So while even infants can experience social joy in laughing, it takes a more mature and socially sophisticated mind to understand the complexity of taunting. “The dark side of laughter is that with maturation one can obtain in-group social joy at the cost of marginalizing others with taunting laughter,” Panksepp says. “Joyful laughter is infectious and brings people together; taunting laughter is not, since it is discriminatory. Clearly, we are still just barely beginning to fathom the many ways laughter [affects] our brains.” And as we do, we may understand a lot more about how laughing helps us to connect — or not — with others.