title: The coevolution of innovation and technical intelligence in primates.
abstract: 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.
authors.affiliation: School of Biology, University of St Andrews, St Andrews, Fife KY16 9TS, UK afn2@st-andrews.ac.uk.
authors.forename: Ana F
authors.identifier: http://orcid.org/0000-0001-6020-0678
authors.initials: AF
authors.lastname: Navarrete
authors.affiliation: Department of Biology, McGill University, 1205 Doctor Penfield Avenue, Montreal, Quebec H3A 1B1, Canada.
authors.forename: Simon M
authors.identifier: http://orcid.org/0000-0002-3785-1357
authors.initials: SM
authors.lastname: Reader
authors.affiliation: School of Biology, University of St Andrews, St Andrews, Fife KY16 9TS, UK School of Biological, Biomedical and Environmental Sciences, University of Hull, Cottingham Road, Kingston upon Hull, Yorkshire HU6 7RX, UK.
authors.forename: Sally E
authors.initials: SE
authors.lastname: Street
authors.affiliation: School of Biology, University of St Andrews, St Andrews, Fife KY16 9TS, UK.
authors.forename: Andrew
authors.initials: A
authors.lastname: Whalen
authors.affiliation: School of Biology, University of St Andrews, St Andrews, Fife KY16 9TS, UK.
authors.forename: Kevin N
authors.initials: KN
authors.lastname: Laland
mesh_terms: D000818:Animals; D001522:Behavior, Animal; D005075:Biological Evolution; D049628:Body Size; D001921:Brain / Q000033:anatomy & histology / Q000502:physiology; D004032:Diet; D007360:Intelligence; D009929:Organ Size; D011323:Primates / Q000235:genetics* / Q000502:physiology*; D012919:Social Behavior
keywords: brain evolution; innovation; intelligence; primate cognition; social learning; tool use