Here's something you probably wouldn't have guessed: more than half of MySpace users are 35 or older. That's according to comScore Media Metrix, which yesterday released the surprising traffic numbers, not just for MySpace but also for the three other top social networks - Facebook, Friendster, and Xanga. Overall, the research firm finds that " significant age differences exist" among the different user basis.

Needless to say, the demographics are causing quite a stir among the digerati, most of whom assumed along with everyone else that social networking is a teenager phenomenon. Not so, says Jack Flanagan of Media Metrix. MySpace has the broadest appeal across age groups, he
notes, while Facebook's niche is the college crowd, Friendster has more adult users, and Xanga.com is popular among younger teens. Those findings are to be expected.

But the 35-year-old-and-above MySpace shocker? "I don't believe [it]," posts John DeMayo, created his own MySpace demographic profile by tallying the number of users in a given age group by zipcodes - and claims his skepticism is warranted. "I think they are counting the head of household's age in their sample, but in reality it's the younger members of the household that are visiting myspace, and being counted as older people."

Liz Gannes at GigaOm also thought Media Metrix might have "gone off the deep end," but she did her checking the easy way: she simply Fox Interactive, whose spokesperson Ann Burkart confirmed that the Media Metrix numbers were consistent with their own. "Burkart’s explanation is that as MySpace expands it is becoming more representative of the population as a whole," writes Gannes.

Indeed, according to the data, there are almost as many MySpace users 55 and over as there are under 18. The Browser has at least one simple explanation for all the oldsters, beyond all the 30-something rockers hanging on to their dreams of rock-and-roll stardom: parents. Given the threat of sexual predators trolling MySpace, many parents now visit their kids pages, and even set up their own pages in order to keep a closer eye on things. Certainly this means MySpace is becoming more representative of broader demographics. Whether these adult tourists are as engaged with the media as their kids - or as likely to click on ads - remains to be seen.