title: The sociality-health-fitness nexus: synthesis, conclusions and future directions.
abstract: This theme issue has highlighted the links between sociality, health and fitness in a broad range of organisms, and with approaches that include field and captive studies of animals, comparative and meta-analyses, theoretical modelling and clinical and psychological studies of humans. In this concluding chapter, we synthesize the results of these diverse studies into some of the key concepts discussed in this issue, focusing on risks of infectious disease through social contact, the effects of competition in groups on susceptibility to disease, and the integration of sociality into research on life-history trade-offs. Interestingly, the studies in this issue both support pre-existing hypotheses, and in other ways challenge those hypotheses. We focus on unexpected results, including a lack of association between ectoparasites and fitness and weak results from a meta-analysis of the links between dominance rank and immune function, and place these results in a broader context. We also review relevant topics that were not covered fully in this theme issue, including self-medication and sickness behaviours, society-level defences against infectious disease, sexual selection, evolutionary medicine, implications for conservation biology and selective pressures on parasite traits. We conclude by identifying general open questions to stimulate and guide future research on the links between sociality, health and fitness.
authors: Department of Evolutionary Anthropology, Duke University, Box 90383, Durham, NC 27708, USA Duke Global Health Institute, Duke University, 310 Trent Drive, Durham, NC 27710, USA charles.nunn@duke.edu.
authors: Charles L
authors: CL
authors: Nunn
authors: Department of Veterinary Population Medicine, University of Minnesota, St Paul, MN 55108, USA.
authors: Meggan E
authors: ME
authors: Craft
authors: Department of Environmental Sciences and Program in Population Biology, Ecology and Evolution, Emory University, Atlanta, GA 30322, USA Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, GA 30322, USA.
authors: Thomas R
authors: TR
authors: Gillespie
authors: Department of Psychology, University of British Columbia, 2136 West Mall, Vancouver, British Columbia, Canada V6T1Z4.
authors: Mark
authors: M
authors: Schaller
authors: Behavioral Ecology and Sociobiology Unit, German Primate Center, Göttingen, Germany Department of Sociobiology/Anthropology, University of Göttingen, Göttingen, Germany.
authors: Peter M
authors: PM
authors: Kappeler
mesh_terms: D000818:Animals; D005075:Biological Evolution; D003141:Communicable Diseases / Q000209:etiology; D004198:Disease Susceptibility; D005260:Female; D056084:Genetic Fitness; D006304:Health Status; D006790:Host-Parasite Interactions; D006801:Humans; D008297:Male; D008954:Models, Biological; D012743:Sex Preselection; D012749:Sexually Transmitted Diseases / Q000209:etiology; D012919:Social Behavior
keywords: evolutionary medicine; fitness; health; infectious disease; social contact; sociality