Many psychologists argue that psychological traits found in modern human beings exist not merely by happenstance but because our distant ancestors who possessed a given trait were better adapted to their environment and thus survived (at least long enough to propagate their genes) while humans possessing other, less well-adapted traits died out.
USA Today reports on a new study in this vein:
Gossip, whether “delicious or destructive,” serves a function, according to the study [by Anderson et. al.], to be published online May 19 by the journal Science. In lieu of direct experience, social tittle-tattle allows people to learn about others across a very wide group, the team say. That, in turn, gives people cues on who to befriend (or not) without having to actually have to spend lots of time with them first.
The Anderson et. al. article is available online here (subscription required).