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- PublicationMétadonnées seulementEndogenous oxytocin predicts helping and conversation as a function of group membershipHumans cooperate with unrelated individuals to an extent that far outstrips any other species. We also display extreme variation in decisions about whether to cooperate or not, and the mechanisms driving this variation remain an open question across the behavioural sciences. One candidate mechanism underlying this variation in cooperation is the evolutionary ancient neurohormone oxytocin (OT). As current research focuses on artificial administration of OT in asocial tasks, little is known about how the hormone in its naturally occurring state actually impacts behaviour in social interactions. Using a new optimal foraging paradigm, the ‘egg hunt’, we assessed the association of endogenous OT with helping behaviour and conversation. We manipulated players' group membership relative to each other prior to an egg hunt, during which they had repeated opportunities to spontaneously help each other. Results show that endogenous baseline OT predicted helping and conversation type, but crucially as a function of group membership. Higher baseline OT predicted increased helping but only between in-group players, as well as decreased discussion about individuals’ goals between in-group players but conversely more of such discussion between out-group players. Subsequently, behaviour but not conversation during the hunt predicted change in OT, in that out-group members who did not help showed a decrease in OT from baseline levels. In sum, endogenous OT predicts helping behaviour and conversation, importantly as a function of group membership, and this effect occurs in parallel to uniquely human cognitive processes.
- PublicationMétadonnées seulementWhy mutual helping in most natural systems is neither conflict-free nor based on maximal conflictMutual helping for direct benefits can be explained by various game theoretical models, which differ mainly in terms of the underlying conflict of interest between two partners. Conflict is minimal if helping is self-serving and the partner benefits as a by-product. In contrast, conflict is maximal if partners are in a prisoner's dilemma with both having the pay-off-dominant option of not returning the other's investment. Here, we provide evolutionary and ecological arguments for why these two extremes are often unstable under natural conditions and propose that interactions with intermediate levels of conflict are frequent evolutionary endpoints. We argue that by-product helping is prone to becoming an asymmetric investment game since even small variation in by-product benefits will lead to the evolution of partner choice, leading to investments by the chosen class. Second, iterated prisoner's dilemmas tend to take place in stable social groups where the fitness of partners is interdependent, with the effect that a certain level of helping is self-serving. In sum, intermediate levels of mutual helping are expected in nature, while efficient partner monitoring may allow reaching higher levels.
- PublicationMétadonnées seulementDifferences in Diet Between Six Neighbouring Groups of Vervet Monkeys(2014)
;Tournier, Emilie ;Tournier, Virginia ;Waal, Erica ;Barrett, Alan ;Brown, Leslie
- PublicationMétadonnées seulementFish choose appropriately when and with whom to collaborate(2014)
;Vail, Alexander L ;Manica, Andrea
- PublicationMétadonnées seulementNo scope for social modulation of steroid levels in a year-round territorial damselfish
- PublicationMétadonnées seulementReferential gestures in fish collaborative hunting(2013)
;Vail, Alexander L. ;Manica, Andrea
- PublicationMétadonnées seulementNegotiations over Grooming in Wild Vervet Monkeys (Chlorocebus pygerythrus)
- PublicationMétadonnées seulementArginine Vasotocin Neuronal Phenotype and Interspecific Cooperative Behaviour(2013)
;Mendonca, Rute ;Soares, Marta ;Oliveira, Rui F.
- PublicationMétadonnées seulementThird-Party Ranks Knowledge in Wild Vervet Monkeys (Chlorocebus aethiops pygerythrus)
- PublicationMétadonnées seulementPhilopatric vervet monkey females are the focus of social attention rather independently of rank(2013)
;Renevey, Nathalie ;van de Waal, Erica