Turnover in Social Network Sites

Stowe Boyd points to another article that was put together by danah boyd and Fred Stutzman. To paraphrase - individuals join social networks for specific reasons, to fill specific desires.  Once they are filled, or change, they may leave the network. It is really a simple idea that mimics real life. As we progress through life our circle of friends changes in a constant state of flux.  Once we leave college our college friends slowly drift away. If we move, join a new country club, change jobs, or even have children our circle of friends changes. It is wholly reasonable to expect network sites to act in a similar fashion.