Universal Principles of Design, Updated and Expanded Third Edition

052 Dunbar’s Number

The maximum number of relationships a person can comfortably maintain.

Dunbar’s number, proposed by the anthropologist Robin Dunbar, states that there is a limit to the number of meaningful relationships people can maintain. The limit is a function of the information-processing power of the brain, derived from correlations between brain size and group size in various primates: The larger the primate brain, the larger their group sizes. For human primates, the group size maximum is about 150 members.1

The proposed number of 150 refers to the maximum number of meaningful relationships a person can maintain. A meaningful relationship is loosely defined as one in which two people would go out of their way to greet one another ...