title: Infectious disease, behavioural flexibility and the evolution of culture in primates.
abstract: Culturally transmitted traits are observed in a wide array of animal species, yet we understand little about the costs of the behavioural patterns that underlie culture, such as innovation and social learning. We propose that infectious diseases are a significant cost associated with cultural transmission. We investigated two hypotheses that may explain such a connection: that social learning and exploratory behaviours (specifically, innovation and extractive foraging) either compensate for existing infection or increase exposure to infectious agents. We used Bayesian comparative methods, controlling for sampling effort, body mass, group size, geographical range size, terrestriality, latitude and phylogenetic uncertainty. Across 127 primate species, we found a positive association between pathogen richness and rates of innovation, extractive foraging and social learning. This relationship was driven by two independent phenomena: socially contagious diseases were positively associated with rates of social learning, and environmentally transmitted diseases were positively associated with rates of exploration. Because higher pathogen burdens can contribute to morbidity and mortality, we propose that parasitism is a significant cost associated with the behavioural patterns that underpin culture, and that increased pathogen exposure is likely to have played an important role in the evolution of culture in both non-human primates and humans.
authors.affiliation: Department of Human Evolutionary Biology, Harvard University, 11 Divinity Avenue, Cambridge, MA 02138, USA mccabe@fas.harvard.edu.
authors.forename: Collin M
authors.identifier: http://orcid.org/0000-0003-0836-7117
authors.initials: CM
authors.lastname: McCabe
authors.affiliation: Department of Biology, McGill University, 1205 avenue Docteur Penfield, Montréal, Québec H3A 1B1, Canada Department of Biology and Helmholtz Institute, Utrecht University, Padualaan 8, 3584 Utrecht, The Netherlands.
authors.forename: Simon M
authors.identifier: http://orcid.org/0000-0002-3785-1357
authors.initials: SM
authors.lastname: Reader
authors.affiliation: Department of Human Evolutionary Biology, Harvard University, 11 Divinity Avenue, Cambridge, MA 02138, USA Department of Evolutionary Anthropology, Duke University, Biological Sciences Building, Durham, NC 27708, USA Duke Global Health Institute, Trent Drive, Duke University, Durham, NC 27708, USA.
authors.forename: Charles L
authors.initials: CL
authors.lastname: Nunn
mesh_terms: D000818:Animals; D001499:Bayes Theorem; D001522:Behavior, Animal; D005075:Biological Evolution; D003141:Communicable Diseases / Q000469:parasitology; D003468:Cultural Evolution; D018562:Disease Transmission, Infectious; D004777:Environment; D007858:Learning; D010802:Phylogeny; D011323:Primates / Q000469:parasitology / Q000502:physiology*; D012919:Social Behavior
keywords: behavioural innovation; comparative study; cultural evolution; parasitism; social learning