http://www.bloomberg.com/bw/articles/2013-01-10/the-dunbar-number-from-the-guru-of-social-networks For Dunbar, there’s a simple explanation for this: In the same way that human beings can’t breathe underwater or run the 100-meter dash in 2.5 seconds or see microwaves with the naked eye, most cannot maintain many more than 150 meaningful relationships. Cognitively, we’re just not built for it.
http://www.wired.com/2012/03/dunbars-number-facebook/ Before I hit the J’s, I converted to Facebook’s Timeline. As a result, I lost access to the alphabetical friend list, which brought my social experiment to a screeching halt. In trying to disprove Dunbar’s number, I actually proved it. I only made it through 1,000 of my 2,000
https://en.wikipedia.org/wiki/Dunbar%27s_number Dunbar’s number is a suggested cognitive limit to the number of people with whom one can maintain stable social relationships. These are relationships in which an individual knows who each person is and how each person relates to every other person. This number was first proposed in the 1990s