Cited 62 times since 2012 (4.6 per year) source: EuropePMC Trends in cognitive sciences, Volume 16, Issue 5, 17 3 2012, Pages 277-284 Explaining brain size variation: from social to cultural brain. van Schaik CP, Isler K, Burkart JM

Although the social brain hypothesis has found near-universal acceptance as the best explanation for the evolution of extensive variation in brain size among mammals, it faces two problems. First, it cannot account for grade shifts, where species or complete lineages have a very different brain size than expected based on their social organization. Second, it cannot account for the observation that species with high socio-cognitive abilities also excel in general cognition. These problems may be related. For birds and mammals, we propose to integrate the social brain hypothesis into a broader framework we call cultural intelligence, which stresses the importance of the high costs of brain tissue, general behavioral flexibility and the role of social learning in acquiring cognitive skills.

Trends Cogn Sci. 2012 4;16(5):277-284