New approach illuminates switch

prefrontal cortex correlate with the size of social group in which individuals were housed. Remarkably, they were also able to demonstrate that, within social groups, there were correlations between the volumes of these same regions and the dominance ranks of individual monkeys. The Sallet et al. results are important for two reasons. First, they confirm that the findings reported for humans apply more generally to other primates, thereby providing a unifying framework for the social brain hypothesis. Second, 2 Shultz, S. and Dunbar, R. (2010) Encephalisation is not a universa macroevolutionary phenomenon in mammals but is associated wit sociality. Proc. Natl. Acad. Sci. U.S.A. 107, 21582–21586 3 Stiller, J. and Dunbar, R.I.M. (2007) Perspective-taking and socia network size in humans. Soc. Netw. 29, 93–104 4 Sallet, J. et al. (2011) Social network size affects neural circuits i macaques. Science 334, 697–700 5 Bickart, K. et al. (2010) Amygdala volume and social network size i humans. Nat. Neurosci. 14, 163–164 6 Kanai, R. et al. (2011) Online social network size is reflected in huma brain structure. Proc. R. Soc. B: Biol. Sci. DOI: 10.1098/rspb.2011.195 Spotlights Trends in Cognitive Sciences February 2012, Vol. 16, No.