Although wild claims have been made about the number of friends people have on Facebook, the vast majority of us have only 120-130. Yes, you can have 500 or 1,000 friends if you want to sign people up, but this seems to have more to do with COMPETITION than with real friendship.
On average, we have:
5 intimate friends,
15 good friends (including the five intimate ones),
50 friends and
While it is not altogether clear why our relationships are constrained in this way, one possibility is time. A relationship’s quality seems to depend on how much time we devote to it, and since time is limited, we necessarily have to distribute what time we do have for social engagement unevenly. We focus most of it on our inner core of five intimates. Alternatively, it might just be a memory problem: we have a job keeping track of who’s doing what, and can only really keep serious tabs on the inner core of five.
Robin Dunbar is professor of evolutionary anthropology at Oxford University.