Ever heard of Dunbar's Number? According to British anthropologist Robin Dunbar, it's the cognitive limit to the number of people you can be friends with. The number is 150, meaning your brain can only handle that many friends, and -- shockingly enough -- it also applies to Facebook.
Even if you have thousands of friends, that number is really meaningless as far as true friendships go, Dunbar told Times Online. He supports this with traffic data. “The interesting thing is that you can have 1,500 friends but when you actually look at traffic on sites, you see people maintain the same inner circle of around 150 people that we observe in the real world,” he said.
This is a well-known concept. The company that produces Gore-Tex fabrics, Gore (as famously explained in Malcolm Gladwell's book The Tipping Point), keeps its employees divided into small teams because in very large teams the relationship between people starts to deteriorate.
The number is a bit different for boys and girls, Dunbar claims, without going into specifics. “There is a big sex difference though ... girls are much better at maintaining relationships just by talking to each other. Boys need to do physical stuff together,” he said.