Dunbar’s Number is a suggested cognitive limit to the number of people with whom one can maintain stable social relationships—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 by British anthropologist Robin Dunbar, who found a correlation between primate brain size and average social group size. By using the average human brain size and extrapolating from the results of primates, he proposed that humans can comfortably maintain 150 stable relationships. Dunbar explained it informally as “the number of people you would not feel embarrassed about joining uninvited for a drink if you happened to bump into them in a bar.”
Source: Dunbar’s number – Wikipedia
I have finally run across the term for my problem with Facebook: Dunbar’s Number. Old relationships from decades ago should be allowed to die off as you make new relationships. 150 people feels about right. Having 1,000-2,000 “friends” on Facebook makes literally no sense. Similarly, following 4,000 people on Twitter makes literally no sense. People require context to make sense of comments and pictures, and when you have that many people on a feed of any kind, context becomes impossible to distinguish.