The function of greetings in male Tonkean macaques

Abstract

Males living in multi-male groups are both strong rivals and potential allies. In several primate species they regularly interact through ritualized exchanges known as greetings. We studied five captive groups of Tonkean macaques (Macaca tonkeana) to test five hypotheses regarding the social function of greetings. We found that greetings were mostly reciprocal interactions, and that they often involved physical contact and facial displays. Although they were mostly initiated by the higher-ranking individual in each dyad, subordinates could initiate approximately one-third of greetings, which indicates that greetings do not serve as a formal acknowledgement of dominance relationships. Although greeting frequencies were negatively correlated to the frequency of supplantations and conflicts, they were not significantly influenced by age and dominance status, showing that greetings are not used to appease partners or decrease tension between males. Males most frequently greeted partners with whom they spent more time in proximity and body contact, and this is consistent with the hypothesis that greetings play a role in reinforcing social relationships. Lastly, greetings increased in frequency between individuals involved in challenges for rank, lending support to the hypothesis that males assess the state of their social relationships through greetings.

Rudimentary empathy in macaques’ social decision-making

“…Hence, to act in accordance with their motivation for social interaction, macaques need to be able to predict the consequences of their behavior on future social bonds. Moreover, greeting rituals constitute evidence that macaques react to other's absence, suggesting a persistent mental representation and a specific need to interact with a given conspecific (63,64). Beyond the claim that macaques are natural born politicians, we believe that a cognitive control of vicarious affect allows macaques to include (or discard) others' welfare into their social decision framework and thus shape their social network.…”

Female mate choice and male–male competition in Tonkean macaques: Who decides?

“…He used aggression against the female when the latter approached other males, but generally did not do so when the female was approached by other males. In this case, the guarding individual was more likely to interpose himself between partners or display affiliative behaviours towards the rival; males do indeed monitor and reaffirm their social relationships through such greeting interactions (De Marco, Cozzolino, Dessì‐Fulgheri, & Thierry, 2011b; De Marco et al., ). It should be added that females did not suffer any physical costs, nor did males used aggression to force reluctant females into copulation.…”

“…The guarding male was more likely to move towards and/or threaten T A B L E 3 Results of Wald tests for the best-fitting general linear mixed model models retained using the Akaike information criterion (AICc) regarding the frequencies of sexual presentations and mounts De Marco et al, 2014). It should be added that females did not suffer any physical costs, nor did males used aggression to force reluctant females into copulation.…”

“…This species originates from the island of Sulawesi, Indonesia, and lives in multimale–multifemale groups. Tonkean macaques are among the most tolerant species of the genus Macaca as indicated by several behavioural indices: in comparison with other macaques (Thierry, ), their social style is characterised by a shallow dominance gradient, that is, weak power differentials among individuals, and a high propensity to regulate social tension through multiple affiliative behaviours, frequent reconciliations and peaceful interventions in conflicts (De Marco, Cozzolino, Dessì‐Fulgheri, & Thierry, 2011a; De Marco, Sanna, Cozzolino, & Thierry, ; Demaria & Thierry, ; Petit & Thierry, ). Reproduction occurs all year round, and sexual dimorphism is marked (Sanna, De Marco, Thierry, & Cozzolino, ).…”

Capuchin monkey rituals: an interdisciplinary study of form and function

“…religious rituals : Bell 1997;Durkheim 1912;Rossano 2010;Sosis and Alcorta 2003) and for some types of nonhuman rituals (e.g. De Marco et al 2014;Perry et al 2003;Watanabe and Smuts 1999;Whitham and Maestripieri 2003), that ritual serves a social bonding function, enhancing feelings of solidarity, trust and desire to collaborate, or at least testing commitment to a particular group or partner(s). Although testing these functional hypotheses is difficult in both humans and nonhumans, the evidence from capuchins is generally consistent with the idea that capuchin dyadic rituals serve a bond-testing function.…”