Supplementary datasetThis dataset includes data from 167 primate species, categorized as innovators if Reader et al. (2011) reported more than zero innovations for the species, and as non-innovators if they reported zero innovations species (column “Innovator”). The dataset includes species scores for different types of innovation which were calculated using the records of Simon Reader (numbers of technical innovations, non-technical innovations, technical innovations including extractive foraging, non-technical innovations excluding extractive foraging, technical foraging innovations, non-technical foraging innovations, technical foraging innovations including extractive foraging, and non-technical foraging innovations excluding extractive foraging), and the scores of a life history composite obtained using phylogenetic principal component analysis on six life history variables. We also provide three columns (“Species (Arnold et al. 2010)”, “Species (Isler et al. 2008)”, and “Species (Reader et al. 2011)”) where we provide details on differences of nomenclature between the sources of the rest of the variables used in this study and the nomenclature in our phylogenetical tree. We used the used the 10 k Trees project dated consensus tree (v.3) for phylogeny (Arnold, Matthews, & Nunn, 2010). Body mass averages and endocraneal volume (ECV) averages per species were extracted from Isler et al. (2008). Measures of zoological records, social transmission, innovation and diet breadth were extracted from Reader et al. (2011). Social group size and six life history variables (gestation length, interbirth interval, weaning age, age of sexual maturity, age at first birth and maximum longevity) were extracted from Jones et al. (2009). Arnold, C., Matthews, L. J., & Nunn, C. L. (2010). The 10k Trees Website: A New Online Resource for Primate Phylogeny. Evolutionary Anthropology, 19(3), 114-118. doi: 10.1002/evan.20251 Isler, K., Kirk, C. E., Miller, J. M. A., Albrecht, G. A., Gelvin, B. R., & Martin, R. D. (2008). Endocranial volumes of primate species: scaling analyses using a comprehensive and reliable data set. Journal of Human Evolution, 55(6), 967-978. doi: 10.1016/j.jhevol.2008.08.004 Jones, K. E., Bielby, J., Cardillo, M., Fritz, S. A., O'Dell, J., Orme, D. L., . . . Purvis, A. (2009). PanTHERIA: a species-level database of life history, ecology, and geography of extant and recently extinct mammals. Ecology, 90(9), 2648-2648. doi: 10.1890/08-1494.1 Reader, S. M., Hager, Y., & Laland, K. N. (2011). The evolution of primate general and cultural intelligence. Philosophical Transactions of the Royal Society B: Biological Sciences, 366(1567), 1017-1027. doi: http://dx.doi.org/10.5061/dryad.t0q94ESMNavarreteReaderStreetWhalenLaland_dataset.csv

In birds and primates, the frequency of behavioural innovation has been shown to covary with absolute and relative brain size, leading to the suggestion that large brains allow animals to innovate, and/or that selection for innovativeness, together with social learning, may have driven brain enlargement. We examined the relationship between primate brain size and both technical (i.e. tool using) and non-technical innovation, deploying a combination of phylogenetically informed regression and exploratory causal graph analyses. Regression analyses revealed that absolute and relative brain size correlated positively with technical innovation, and exhibited consistently weaker, but still positive, relationships with non-technical innovation. These findings mirror similar results in birds. Our exploratory causal graph analyses suggested that technical innovation shares strong direct relationships with brain size, body size, social learning rate and social group size, whereas non-technical innovation did not exhibit a direct relationship with brain size. Nonetheless, non-technical innovation was linked to brain size indirectly via diet and life-history variables. Our findings support ‘technical intelligence’ hypotheses in linking technical innovation to encephalization in the restricted set of primate lineages where technical innovation has been reported. Our findings also provide support for a broad co-evolving complex of brain, behaviour, life-history, social and dietary variables, providing secondary support for social and ecological intelligence hypotheses. The ability to gain access to difficult-to-extract, but potentially nutrient-rich, resources through tool use may have conferred on some primates adaptive advantages, leading to selection for brain circuitry that underlies technical proficiency.