The old people are crashing the party at social networking sites. Despite conventional wisdom that sites like MySpace are entirely the domain of the young and wireless demographic, the vast majority of users logging on to some of the most popular social networking sites are over 25 years old, according to new figures released by comScore Media Metrix.

For example, according to comScore, 68 percent of the 55 million MySpace users are 25 and older, while 71 percent of the 1 million users on the declining Friendster fall within the same demographic. Even Facebook, which up until recently was limited to college and high school students, boasts of a growing audience 15 million users - 50 percent of whom are 25-plus. Contrasty, the smaller and less popular Xanga.com is considerably younger, as 20 percent of its 8.1 million user base falls within the 12-17 demographic.

The relative aging of the giant social networks indicates that their recent exponential growth has been driven by new and older Web users discovering the phenomenon. For example, back in August of 2005, teens made up a quarter of the MySpace audience. Now that group represents just 12 percent of users. During the same period, the middle-aged crowd has been gravitating to the site in droves: adults 35-54 now make up more than 40 percent of the site, up 8 percentage points in the last year.

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