Turns out there's some human desire behind all those Facebook selfies and the constant tweeting: it's narcissism, according to one study.
The "amount of time that a person spends on social media speaks volumes about his or her personality," according to SF Weekly. "The more you tweet, the bigger your ego, and the more you Facebook, the bigger your need for approval."
The study comes from the University of Michigan, which noticed that different forms of narcissism present themselves on different forms of social media: Show-offs, the newspaper reported, tend to tweet more. Whereas people who need affirmation -- people who "are more concerned with their own appearance" -- post on Facebook and wait for the parade of "likes."
So Twitter is for me-first millennials, Facebook is for older folks posting photos of their kids and their just-cooked dinners, the newspaper reported.