A Statistical Modelling Approach to the Occurrence and Timing of Reconciliation in Wild Japanese Macaques

Abstract

In various social species, animals have been observed to share friendly relationships with some group members and to resolve conflicts through reconciliation, the exchange of affiliative behaviour soon after a conflict that functions to restore the relationship between the former opponents. The valuable relationship hypothesis predicts that reconciliation should be observed more often after conflicts between friends. Friendly relationships can be described by three dimensions (i.e. value, security and compatibility); however, research into the relative importance of these dimensions for the occurrence of reconciliation is sparse. Moreover, reconciliation may depend on factors other than the social relationship between opponents including, for example, their social status or the context of the conflict. Our study aimed at analysing which factors are important determinants of reconciliation and at testing the valuable relationship hypothesis, by analysing the relative effects of relationship value, security and compatibility on the occurrence and timing of reconciliation. We collected data on two troops of wild Japanese macaques living on Yakushima Island, Japan, and selected the best predicting variables of reconciliation using linear mixed models. Our results show that reconciliation occurs more frequently, and earlier, after conflicts between opponents who exchange a higher percentage of grooming. Two additional variables related to relationship security and value were selected in the best models: frequency of aggression and of approaches resulting in tolerated co‐feeding. Among the variables not related to relationship quality, distance between opponents at the end of the conflict, kinship, sex of the opponents and context of conflict (i.e. during feeding or social time) were included in our models. Our findings support the valuable relationship hypothesis and, in particular, highlight that the fitness‐related benefits of social relationships (i.e. the relationship value) are important determinants of the evolution of friendly relationships and reconciliation.

Postconflict Behaviour in Brown Capuchin Monkeys (Cebus apella)

“…These results are in agreement with the idea that the value of a relationship is the most important determinant of conflict resolution, while compatibility and security play a less relevant role [Majolo et al, 2009]. Despite recent efforts to group different measures of social interactions into the three dimensions of relationship quality [Fraser et al, 2008], further studies are needed to examine the consistency of these results in other species.…”

“…Social relationship variables, together with dominance ranks, were computed separately for 2004 and 2005 data. Social variables were assigned to the different dimensions of relationship quality according to Fraser et al [2008] and Majolo et al [2009]. Both studies use grooming reciprocation as an indicator of relationship security.…”

“…Both value and compatibility have been shown to be positively associated with the likelihood of reconciliation [Cords and Aureli, 2000;Aureli et al, 2002;Watts, 2006;Arnold and Aureli, 2007], although many of the studies where associations were found are based on the assumption that broad categories, such as kinship or age-sex combinations, index different dimensions of relationship quality [Fraser et al, 2008]. Few studies on conflict resolution focus on more than a couple of measures of relationship, and the difficulties in reliably assessing relationship security have meant that even fewer have investigated all 3 components [Cords and Aureli, 2000;Aureli et al, 2002;Watts, 2006;Arnold and Aureli, 2007;Fraser et al, 2008;Majolo et al, 2009].…”

Conflicts induce affiliative interactions among bystanders in a tolerant species of macaque (Macaca tonkeana)

“…The likelihood and timing of reconciliation are known to be influenced by the characteristics of conflicts, that is, duration, intensity, occurrence of intervention, decidedness of outcome, and those of the opponents, that is, sex, age and dominance rank (Aureli et al 1989;Call et al 1999;Arnold & Aureli 2007;Majolo et al 2009a). A multivariate approach showed that quadratic affiliation in Tonkean macaques occurred earlier after conflicts involving physical contact.…”

Use of Robots in Behavioral Studies on Primates

“…集団で生活する霊長類は，複雑な社会の中で生活を している。霊長類の社会行動を研究する場合，血縁や 順位，親密さといった要因が注目される。例えば，集 団の各個体間には優劣関係があり，劣位個体は優位個 体に多く毛づくろいをする傾向があると指摘されてい る (Seyfarth, 1977;Schino, 2001; 上野 , 2016) 。 し か し， すべての個体がそのように行動するわけではなく，優 劣関係が比較的明瞭なニホンザル(Macaca fuscata)集 団の中にも，優位個体から劣位個体に毛づくろいを多 く行う個体がいる (Nakamichi & Shizawa, 2003 (Koyama, 2001) 。血縁個体間や，普段近接や毛づくろいをするこ との多い個体との間で攻撃が生じた場合には，比較的 高い割合で仲直り行動が行われる (Kutsukake & Castle, 2001;Majolo et al, 2009) 。このような知見から，攻撃交 渉の直後に行われる毛づくろい等の行動は，攻撃交渉 によって損なわれた社会関係を修復する機能を持つと 考えられている (Aureli et al, 2002) 。 しかし，霊長類の「仲直り」が，どの行動によって 成立しているのかに関しては疑問の余地がある (Silk et al, 1996) (Tanaka & Takefushi, 1993;Zamma, 2002) et al, 1999;Ueno et al, 2015) Parton et al(2009) …”