Play and post-conflict mechanisms in wolves: a comparison with human and non-human primates.

Cooperation is a series of coordinated interactions in which participants take turns in giving and receiving benefits. Nevertheless, competition is the other side of the coin and it may generate aggression among conspecifics loosing social cohesion. Many social species have developed behavioral strategies to cope with social damage caused by competition. We investigated the occurrence and dynamics of these behavioral strategies in wolves (Canis lupus lupus), a species characterized by high sociality and cooperation levels, by carrying out a long-term observational study on the grey wolf colony hosted at the Pistoia Zoo (Italy). We highlighted the occurrence of post-conflict affiliation both between opponents (reconciliation) and between victims and bystanders (solicited and unsolicited contacts). Reconciliation was uniformly distributed across the different sex-class combinations and seemed to be not affected by the hierarchical relationships. Moreover, coalitionary support given to victim and/or to aggressor during a conflict may be a good predictor for high level of reconciliation. Concerning unsolicited triadic contacts (named “consolation” in human and non-human primates), we found that this affilation was more frequent between individuals sharing good relationships and was reciprocated between partners (victims and third-parties), thus suggesting the reciprocal nature of this mechanism (mutualistic behavior). As it occurs in human and non-human primates, unsolicited contacts provide immediate benefits to the victim by breaking-off aggression and restoring victim’ social cohesiveness. To investigate other affinitive behaviors used by wolves to promote cohesiveness and cooperation, we evaluated the presence of social play, an activity used by animals for self- and social-assessment purposes. We showed the occurrence of adult play in wolves. Play distribution is not affected by relationship quality and aggression level, thus suggesting that other strategies are employed for strengthening inter-individual relationships and reducing aggressiveness. Rank distance between conspecifics negatively correlate with play distribution: by playing wolves with closest ranking positions tested each other for acquiring information on motor and psychological skills of possible competitors and for gaining hierarchical advantage over it. The overall findings on wolves strongly match with those coming from behavioral studies on human and non-human primates. Even though further comparative-cognitive studies are needed in canids, the similarities between primate and wolf social cohesion strategies suggest an evolutionary convergence in certain traits of cognitive skills at the basis of natural conflict resolution and adult social play.