Jim Rutt defines the Dunbar Number as the cognitive limit to the number of stable social relationships a person can maintain. Named after British anthropologist Robin Dunbar, this concept posits that there is a cap to the number of meaningful connections one individual can manage, typically around 150 people. Rutt emphasizes that this limit stems from the constraints of the human brain, particularly the neocortex, and the complexities involved in maintaining cohesive and functional social networks. He highlights that these relationships are not just fleeting interactions, but ones where an individual knows who each person is and how each person relates to every other person within the group. This theory has implications for understanding social structures, community organization, and even the development of digital social networks.

See also: evolutionary psychology, edge of chaos, cultural evolution