Dunbar Number

cognitive limit to the number of individuals with whom any one person can maintain stable relationships

from Robin Dunbar

http://en.wikipedia.org/wiki/Dunbar's_number

In a 1993 article, Dunbar used the correlation observed for non-human primates to predict a social group size for humans. Using a regression equation on data for 36 primate genera, Dunbar predicted a human "mean group size" of 147.8 (casually represented as 150), a result he considered exploratory due to the large error measure (a 95% confidence interval of 100 to 230).... Dunbar noted that the groups fell into three categories - small, medium and large, equivalent to bands, cultural lineage groups and tribes - with respective size ranges of 30-50, 100-200 and 500-2500 members each.

limit to your Social Network?

http://stoweboyd.com/post/814857072/seth-godin-misunderstands-dunbars-number-and-stubs

It's all about the Monkey Sphere.