As the number of nodes increases, the number of connections between nodes increases as the square of the number of nodes.

The Dunbar number of about 150 appears to limit the human size of an organization where everyone can know everyone else.

Dunbar's informal definitions (from the 1990's) is "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.".

More: The Dunbar number