From Scientific American:
In the past few years I have heard more people than ever before puzzling over the 24/7 coverage of people such as Paris Hilton who are “celebrities” for no apparent reason other than we know who they are. And yet we can’t look away. The press about these individuals’ lives continues because people are obviously tuning in. Although many social critics have bemoaned this explosion of popular culture as if it reflects some kind of collective character flaw, it is in fact nothing more than the inevitable outcome of the collision between 21st-century media and Stone Age minds. When you cut away its many layers, our fixation on popular culture reflects an intense interest in the doings of other people; this preoccupation with the lives of others is a by-product of the psychology that evolved in prehistoric times to make our ancestors socially successful. Thus, it appears that we are hardwired to be fascinated by gossip.
Only in the past decade or so have psychologists turned their attention toward the study of gossip, partially because it is difficult to define exactly what gossip is. Most researchers agree that the practice involves talk about people who are not present and that this talk is relaxed, informal and entertaining. Typically the topic of conversation also concerns information that we can make moral judgments about. Gossip appears to be pretty much the same wherever it takes place; gossip among co-workers is not qualitatively different from that among friends outside of work. Although everyone seems to detest a person who is known as a “gossip” and few people would use that label to describe themselves, it is an exceedingly unusual individual who can walk away from a juicy story about one of his or her acquaintances, and all of us have firsthand experience with the difficulty of keeping spectacular news about someone else a secret.