Encyclopedia of Evolutionary Psychological Science

Living Edition
| Editors: Todd K. Shackelford, Viviana A. Weekes-Shackelford

The Social Intelligence Hypothesis

  • Lily Johnson-Ulrich
Living reference work entry
DOI: https://doi.org/10.1007/978-3-319-16999-6_3100-1



The social intelligence hypothesis is a scientific hypothesis proposing that social complexity was the main selective force shaping the evolution of sophisticated intelligence and large brains in extant animals.


The social intelligence hypothesis (SIH) is a popular hypothesis that purports to explain the evolution of large brains and sophisticated cognitive abilities. The SIH proposes that social complexity is cognitively demanding and is thus the key selective pressure affecting brain size and, by extension, intelligence (Dunbar 1998; Humphrey 1976; Jolly 1966). The SIH was originally developed to explain the large brains and intelligent behavior of primates compared to other animals (Dunbar 1998). It has also found support across many mammal and bird species to explain variation in both brain size and cognitive abilities (Dunbar and Shultz 2007; Shultz and...

This is a preview of subscription content, log in to check access.


  1. Barrett, L., Henzi, P., & Dunbar, R. I. M. (2003). Primate cognition: From “what now?” to “what if?”. Trends in Cognitive Sciences, 7(11), 494–497. http://doi.org/10.1016/j.tics.2003.09.005.CrossRefGoogle Scholar
  2. Barton, R. A., & Dunbar, R. I. M. (1997). Evolution of the social brain. In A. Whiten & R. Byrne (Eds.), Machiavellian intelligence II: Extensions and evaluations (Vol. 2, pp. 240–263). Cambridge, UK: Cambridge University Press.Google Scholar
  3. Beauchamp, G., & Fernández-Juricic, E. (2004). Is there a relationship between forebrain size and group size in birds? Evolutionary Ecology Research, 6(6), 833–842.Google Scholar
  4. Benson-Amram, S., Dantzer, B., Stricker, G., Swanson, E. M., & Holekamp, K. E. (2016). Brain size predicts problem-solving ability in mammalian carnivores. Proceedings of the National Academy of Sciences, 113(9), 2532–2537. http://doi.org/10.1073/pnas.1505913113.CrossRefGoogle Scholar
  5. Bergman, T. J., & Beehner, J. C. (2015). Measuring social complexity. Animal Behaviour, 103, 203–209.CrossRefGoogle Scholar
  6. Brothers, L. (1990). The social brain: A project for integrating primate behavior and neurophysiology in a new domain. Concepts in Neuroscience, 1, 27–51.Google Scholar
  7. Bshary, R., Gingins, S., & Vail, A. L. (2014). Social cognition in fishes. Trends in Cognitive Sciences, 18(9), 465–471. http://doi.org/10.1016/j.tics.2014.04.005.CrossRefGoogle Scholar
  8. Burish, M. J., Kueh, H. Y., & Wang, S.-H. (2004). Brain architecture and social complexity in modern and ancient birds. Brain, Behavior and Evolution, 63(2), 107–124.CrossRefGoogle Scholar
  9. Byrne, R. W. (1995). The thinking ape: Evolutionary origins of intelligence. Oxford: Oxford University Press.CrossRefGoogle Scholar
  10. Call, J., & Tomasello, M. (2008). Does the chimpanzee have a theory of mind? 30 years later. Trends in Cognitive Sciences, 12(5), 187–192. http://doi.org/10.1016/j.tics.2008.02.010.CrossRefGoogle Scholar
  11. Chance, M. R. A., & Mead, A. P. (1953). Social behaviour and primate evolution. In Evolution: Symposia of the society for experimental biology (Vol. 7, pp. 395–439).Google Scholar
  12. Cheney, D. L., & Seyfarth, R. M. (1985). Social and non-social knowledge in vervet monkeys. Philosophical Transactions of the Royal Society, B: Biological Sciences, 308(1135), 187–201. http://doi.org/10.1098/rstb.1985.0019.CrossRefGoogle Scholar
  13. Darmaillacq, A.-S., Dickel, L., & Mather, J. (2014). Cephalopod cognition. Cambridge, UK: Cambridge University Press.CrossRefGoogle Scholar
  14. de Waal, F. B. M. (1982). Chimpanzee politics: Power and sex among apes. Baltimore, MD: John Hopkins University Press.Google Scholar
  15. de Waal, F. B. M., & Tyack, P. L. (2009). Animal social complexity: Intelligence, culture, and individualized societies. Cambridge, MA: Harvard University Press.Google Scholar
  16. DeCasien, A. R., Williams, S. A., & Higham, J. P. (2017). Primate brain size is predicted by diet but not sociality. Nature Ecology & Evolution, 1, 112. http://doi.org/10.1038/s41559-017-0112.CrossRefGoogle Scholar
  17. Dunbar, R. I. M. (1998). The social brain hypothesis. Evolutionary Anthropology: Issues, News, and Reviews, 6(5), 178–190.CrossRefGoogle Scholar
  18. Dunbar, R. I. M., & Shultz, S. (2007). Evolution in the social brain. Science (New York, N.Y.), 317(5843), 1344–1347. http://doi.org/10.1126/science.1145463.CrossRefGoogle Scholar
  19. Emery, N. J., & Clayton, N. S. (2004). The mentality of crows: Convergent evolution of intelligence in corvids and apes. Science (New York, N.Y.), 306(5703), 1903–1907. http://doi.org/10.1126/science.1098410.CrossRefGoogle Scholar
  20. Fedorova, N., Evans, C. L., & Byrne, R. W. (2017). Living in stable social groups is associated with reduced brain size in woodpeckers (Picidae). Biology Letters, 13(3), 20170008.CrossRefGoogle Scholar
  21. Finarelli, J. A., & Flynn, J. J. (2009). Brain-size evolution and sociality in Carnivora. Proceedings of the National Academy of Sciences of the United States of America, 106(23), 9345–9349. http://doi.org/10.1073/pnas.0901780106.CrossRefGoogle Scholar
  22. Frith, C. D. (2007). The social brain? Philosophical Transactions of the Royal Society, B: Biological Sciences, 362(1480), 671 LP–671678.CrossRefGoogle Scholar
  23. Gigerenzer, G. (1997). The modularity of social intelligence. In Machiavellian intelligence II: Extensions and evaluations (Vol. 2, p. 264). Cambridge: Cambridge University Press.Google Scholar
  24. Hart, B. L., Hart, L. A., & Pinter-Wollman, N. (2008). Large brains and cognition: Where do elephants fit in? Neuroscience and Biobehavioral Reviews, 32(1), 86–98. http://doi.org/10.1016/j.neubiorev.2007.05.012.CrossRefGoogle Scholar
  25. Holekamp, K. E., & Benson-Amram, S. (2017). The evolution of intelligence in mammalian carnivores. Interface Focus, 7(3), 20160108.CrossRefGoogle Scholar
  26. Holekamp, K. E., Sakai, S., & Lundrigan, B. (2007). The spotted hyena (Crocuta crocuta) as a model system for study of the evolution of intelligence. Journal of Mammalogy, 88(3), 545–554.CrossRefGoogle Scholar
  27. Holekamp, K. E., Dantzer, B., Stricker, G., Shaw Yoshida, K. C., & Benson-Amram, S. (2015). Brains, brawn and sociality: A hyaena’s tale. Animal Behaviour, 103, 237–248. http://doi.org/10.1016/j.anbehav.2015.01.023.CrossRefGoogle Scholar
  28. Humphrey, N. K. (1976). The social function of intellect. In P. P. G. Bateson & R. A. Hinde (Eds.), Growing Points in Ethology(pp. 303–317). Cambridge, UK: Cambridge University Press.Google Scholar
  29. Jolly, A. (1966). Lemur social behavior and primate intelligence. Science, 153(3735), 501–506. http://doi.org/10.1126/science.153.3735.501.CrossRefGoogle Scholar
  30. Lihoreau, M., Latty, T., & Chittka, L. (2012). An exploration of the social brain hypothesis in insects. Frontiers in Physiology, 3, 442.CrossRefGoogle Scholar
  31. Marino, L. (2002). Convergence of complex cognitive abilities in cetaceans and primates. Brain, Behavior and Evolution, 59(1–2), 21–32. http://doi.org/63731.CrossRefGoogle Scholar
  32. Marino, L., Connor, R. C., Fordyce, R.E., Herman, L.M., Hof, P.R., Lefebvre, L., …, Whitehead, H. (2007). Cetaceans have complex brains for complex cognition. PLoS Biology, 5(5), e139. http://doi.org/10.1371/journal.pbio.0050139.CrossRefGoogle Scholar
  33. Marler, P. (1996). Social cognition. In V. Nolan Jr. (Ed.), Current ornithology (pp. 1–32). New York, NY: Plenum Press.Google Scholar
  34. Parker, S. T. (2015). Re-evaluating the extractive foraging hypothesis. New Ideas in Psychology, 37, 1–12. http://doi.org/10.1016/j.newideapsych.2014.11.001.CrossRefGoogle Scholar
  35. Pérez-Barbería, F. J., & Gordon, I. J. (2005). Gregariousness increases brain size in ungulates. Oecologia, 145(1), 41–52.CrossRefGoogle Scholar
  36. Pitnick, S., Jones, K. E., & Wilkinson, G. S. (2006). Mating system and brain size in bats. Proceedings of the Royal Society of London B: Biological Sciences, 273(1587), 719–724.CrossRefGoogle Scholar
  37. Pollen, A. A., Dobberfuhl, A. P., Scace, J., Igulu, M. M., Renn, S. C. P., Shumway, C. A., & Hofmann, H. A. (2007). Environmental complexity and social organization sculpt the brain in Lake Tanganyikan cichlid fish. Brain, Behavior and Evolution, 70(1), 21–39.CrossRefGoogle Scholar
  38. Reader, S. M., & Laland, K. N. (2002). Social intelligence, innovation, and enhanced brain size in primates. Proceedings of the National Academy of Sciences of the United States of America, 99(7), 4436–4441. http://doi.org/10.1073/pnas.062041299.CrossRefGoogle Scholar
  39. Reader, S. M., Hager, Y., Laland, K. N. K., Munch, S. B., Tebbich, S., Bshary, R., … Wheeler, P. (2011). The evolution of primate general and cultural intelligence. Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences, 366(1567), 1017–27. http://doi.org/10.1098/rstb.2010.0342CrossRefGoogle Scholar
  40. Roth, G. (2013). Invertebrate cognition and intelligence. In The long evolution of brains and minds (pp. 107–115). Dordrecht: Springer Netherlands. http://doi.org/10.1007/978-94-007-6259-6_8CrossRefGoogle Scholar
  41. Seyfarth, R. M., & Cheney, D. L. (2012). Social relationships, social cognition, and the evolution of mind in primates. In Handbook of psychology (2nd edn.). Wiley. http://doi.org/10.1002/9781118133880.hop203021.
  42. Seyfarth, R. M., & Cheney, D. L. (2015). Social cognition. Animal Behaviour, 103, 191–202. http://doi.org/10.1016/j.anbehav.2015.01.030.CrossRefGoogle Scholar
  43. Shultz, S., & Dunbar, R. (2010). Encephalization is not a universal macroevolutionary phenomenon in mammals but is associated with sociality. Proceedings of the National Academy of Sciences of the United States of America, 107(50), 21582–21586. http://doi.org/10.1073/pnas.1005246107.CrossRefGoogle Scholar
  44. Swanson, E. M., Holekamp, K. E., Lundrigan, B. L., Arsznov, B. M., & Sakai, S. T. (2012). Multiple determinants of whole and regional brain volume among terrestrial carnivorans. PloS One, 7(6), e38447.CrossRefGoogle Scholar

Copyright information

© Springer International Publishing AG 2017

Authors and Affiliations

  1. 1.Michigan State UniversityEast LansingUSA

Section editors and affiliations

  • Catherine Salmon
    • 1
  1. 1.University of RedlandsRedlandsUSA