title: Responses to social and environmental stress are attenuated by strong male bonds in wild macaques.
abstract: In humans and obligatory social animals, individuals with weak social ties experience negative health and fitness consequences. The social buffering hypothesis conceptualizes one possible mediating mechanism: During stressful situations the presence of close social partners buffers against the adverse effects of increased physiological stress levels. We tested this hypothesis using data on social (rate of aggression received) and environmental (low temperatures) stressors in wild male Barbary macaques (Macaca sylvanus) in Morocco. These males form strong, enduring, and equitable affiliative relationships similar to human friendships. We tested the effect of the strength of a male's top three social bonds on his fecal glucocorticoid metabolite (fGCM) levels as a function of the stressors' intensity. The attenuating effect of stronger social bonds on physiological stress increased both with increasing rates of aggression received and with decreasing minimum daily temperature. Ruling out thermoregulatory and immediate effects of social interactions on fGCM levels, our results indicate that male Barbary macaques employ a tend-and-befriend coping strategy in the face of increased environmental as well as social day-to-day stressors. This evidence of a stress-ameliorating effect of social bonding among males under natural conditions and beyond the mother-offspring, kin or pair bond broadens the generality of the social buffering hypothesis.
authors.affiliation: Primate Social Evolution Group, Courant Research Centre Evolution of Social Behaviour, Georg-August University, Göttingen 37077, Germany; Applied Behavioural Ecology and Ecosystems Research Unit, University of South Africa, Florida 1710, South Africa; cyoung@gwdg.de.
authors.forename: Christopher
authors.initials: C
authors.lastname: Young
authors.affiliation: School of Psychology, University of Lincoln, Lincoln LN6 7TS, United Kingdom; and.
authors.forename: Bonaventura
authors.initials: B
authors.lastname: Majolo
authors.affiliation: The Endocrinology Laboratory, German Primate Center, Göttingen 37077, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Heistermann
authors.affiliation: Primate Social Evolution Group, Courant Research Centre Evolution of Social Behaviour, Georg-August University, Göttingen 37077, Germany;
authors.forename: Oliver
authors.initials: O
authors.lastname: Schülke
authors.affiliation: Primate Social Evolution Group, Courant Research Centre Evolution of Social Behaviour, Georg-August University, Göttingen 37077, Germany;
authors.forename: Julia
authors.initials: J
authors.lastname: Ostner
mesh_terms: D000818:Animals; D001522:Behavior, Animal; D005243:Feces; D005938:Glucocorticoids / Q000378:metabolism; D008251:Macaca / Q000502:physiology*; D008297:Male; D012919:Social Behavior; D013312:Stress, Physiological
chemical_list: D005938:Glucocorticoids
keywords: glucocorticoid metabolites; male social relationships; social bonds; social buffering hypothesis; stress