Evolutionary psychology of gossip
Have You Heard? Gossip Turns Out to Serve a Purpose – New York Times
From the article:
Gossip not only helps clarify and enforce the rules that keep people working well together, studies suggest, but it circulates crucial information about the behavior of others that cannot be published in an office manual. As often as it sullies reputations, psychologists say, gossip offers a foothold for newcomers in a group and a safety net for group members who feel in danger of falling out.