Dunbar's number

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.[1][2]

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.[3] By using the average human brain size and extrapolating from the results of primates, he proposed that humans can comfortably maintain 150 stable relationships.[4] There is some evidence that brain structure predicts the number of friends one has, though causality remains to be seen.[5]

Dunbar explained the principle 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."[6] Dunbar theorised that "this limit is a direct function of relative neocortex size, and that this, in turn, limits group size [...] the limit imposed by neocortical processing capacity is simply on the number of individuals with whom a stable inter-personal relationship can be maintained". On the periphery, the number also includes past colleagues, such as high school friends, with whom a person would want to reacquaint themselves if they met again.[7] Proponents assert that numbers larger than this generally require more restrictive rules, laws, and enforced norms to maintain a stable, cohesive group. It has been proposed to lie between 100 and 250, with a commonly used value of 150.[8][9]

  1. ^ Cite error: The named reference dunbar92 was invoked but never defined (see the help page).
  2. ^ Gladwell, Malcolm (2000). The Tipping Point – How Little Things Make a Big Difference. Little, Brown and Company. pp. 177–181, 185–186. ISBN 978-0-316-34662-7.
  3. ^ Cite error: The named reference facebook study was invoked but never defined (see the help page).
  4. ^ Purves, Dale (2008). Principles of Cognitive Neuroscience. Sunderland, Massachusetts: Sinauer Associates. ISBN 9780878936946.
  5. ^ Hampton, WH; Unger, A; Von Der Heide, RJ; Olson, IR (2016). "Neural connections foster social connections: a diffusion-weighted imaging study of social networks". Social Cognitive and Affective Neuroscience. 11 (5): 721–727. doi:10.1093/scan/nsv153. PMC 4847692. PMID 26755769.
  6. ^ Dunbar, Robin (1998). Grooming, gossip, and the evolution of language (1st Harvard University Press paperback ed.). Cambridge, Massachusetts: Harvard University Press. p. 77. ISBN 978-0674363366. Retrieved 17 December 2016.
  7. ^ Bialik, Carl (16 November 2007). "Sorry, You May Have Gone Over Your Limit of Network Friends". The Wall Street Journal Online. Retrieved 2 December 2007.
  8. ^ Hernando, A.; Villuendas, D.; Vesperinas, C.; Abad, M.; Plastino, A. (2009). "Unravelling the size distribution of social groups with information theory on complex networks". Preprint. arXiv:0905.3704. Bibcode:2009arXiv0905.3704H.
  9. ^ "Don't Believe Facebook; You Only Have 150 Friends". NPR.org. National Public Radio. 4 June 2011.