The English anthropologist Robin Dunbar has argued that 150 people represents the largest group size that human brains can normally cope with, so it may be that communities naturally split if they got any larger. Dunbar has argued that even today, most humans are embedded in intimate networks that are no larger than 150, even if they have more fleeting relationships with many other people. Modern communities are huge, but only because of the creation of special new social structures to hold them together.
