Dunbar's number: Group size and brain physiology in humans reexamined

Jan de Ruiter, Gavin Weston, Stephen M. Lyon

Research output: Contribution to journalArticlepeer-review

41 Citations (Scopus)


Popular academic ideas linking physiological adaptations to social behaviors are spreading disconcertingly into wider societal contexts. In this article, we note our skepticism with one particularly popular-in our view, problematic-supposed causal correlation between neocortex size and social group size. The resulting Dunbar's Number, as it has come to be called, has been statistically tested against observed group size in different primate species. Although there may be reason to doubt the Dunbar's Number hypothesis among nonhuman primate species, we restrict ourselves here to the application of such an explanatory hypothesis to human, culture-manipulating populations. Human information process management, we argue, cannot be understood as a simple product of brain physiology. Cross-cultural comparison of not only group size but also relationship-reckoning systems like kinship terminologies suggests that although neocortices are undoubtedly crucial to human behavior, they cannot be given such primacy in explaining complex group composition, formation, or management.

Original languageEnglish
Pages (from-to)557-568
Number of pages12
JournalAmerican Anthropologist
Issue number4
Publication statusPublished - Dec 2011
Externally publishedYes


  • Dunbar's Number
  • Group size
  • Kinship terminologies
  • Neocortex


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