title: Food sharing is linked to urinary oxytocin levels and bonding in related and unrelated wild chimpanzees.
abstract: Humans excel in cooperative exchanges between unrelated individuals. Although this trait is fundamental to the success of our species, its evolution and mechanisms are poorly understood. Other social mammals also build long-term cooperative relationships between non-kin, and recent evidence shows that oxytocin, a hormone involved in parent-offspring bonding, is likely to facilitate non-kin as well as kin bonds. In a population of wild chimpanzees, we measured urinary oxytocin levels following a rare cooperative event--food sharing. Subjects showed higher urinary oxytocin levels after single food-sharing events compared with other types of social feeding, irrespective of previous social bond levels. Also, urinary oxytocin levels following food sharing were higher than following grooming, another cooperative behaviour. Therefore, food sharing in chimpanzees may play a key role in social bonding under the influence of oxytocin. We propose that food-sharing events co-opt neurobiological mechanisms evolved to support mother-infant bonding during lactation bouts, and may act as facilitators of bonding and cooperation between unrelated individuals via the oxytocinergic system across social mammals.
authors.affiliation: School of Psychology, University of St Andrews, , St Andrews, UK, Department of Primatology, Max Planck Institute for Evolutionary Anthropology, , Leipzig, Germany, Budongo Conservation Field Station (BCFS), , Masindi, Uganda, Department of Anthropology, Boston University, , Boston, MA, USA, Wisconsin National Primate Research Center, , Madison, WI, USA, Cognitive Science Centre, University of Neuchâtel, , Neuchâtel, Switzerland.
authors.forename: Roman M
authors.initials: RM
authors.lastname: Wittig
authors.forename: Catherine
authors.initials: C
authors.lastname: Crockford
authors.forename: Tobias
authors.initials: T
authors.lastname: Deschner
authors.forename: Kevin E
authors.initials: KE
authors.lastname: Langergraber
authors.forename: Toni E
authors.initials: TE
authors.lastname: Ziegler
authors.forename: Klaus
authors.initials: K
authors.lastname: Zuberbühler
mesh_terms: D000818:Animals; D003299:Cooperative Behavior; D005247:Feeding Behavior; D005260:Female; D006120:Grooming; D008297:Male; D009769:Object Attachment; D010121:Oxytocin / Q000652:urine*; D002679:Pan troglodytes / Q000378:metabolism / Q000502:physiology*
chemical_list: D010121:Oxytocin
keywords: bonding mechanism; chimpanzee; cooperation; food-sharing; non-invasive hormone sampling; oxytocin