In canids, play dynamics seem to be more affected by dominance hierarchy rather than cooperative social bonds. To test this hypothesis we studied a colony of grey wolves (Canis lupus lupus). We quantified the dynamics of aggression and hierarchical changes in two periods (Sample 1 and Sample 2). Sample 2 was characterized by higher level of aggressiveness and by a more strict and steep linear hierarchy. The negative correlation between rank distance and play frequency characterizing both periods and the higher play asymmetry in Sample 2 suggest that rank rules dictate play rules thus highlighting the competitive side of wolf play behaviour. The overall affiliation rates showed no variation between the two samples. Yet, play performance was modified. In Sample 2, wolves reduced playful activity, limited the number of players per session and avoided playing during high competition contexts. Our findings support the hypothesis that wolf play is modulated by dominance relationships more than by cooperative social bonds.
Zuckerman  suggested that during their fertile phase hamadryas females can influence the social organization of the whole group. Carpenter  later suggested that females of Macaca mulatta can achieve a higher social rank during the fertile phase. Recent studies confirm that this particular status can induce various behavioural changes, although these are relatively subtle. For example, female plains baboons do not achieve a higher social rank during the fertile phase, but at this time they are more active, spend more time travelling and sit for only periods of a few minutes. Furthermore, proximity between fertile females and males also increases in non-sexual contexts .
Agonistic support occurs when a bystander intervenes in an ongoing conflict. The consequences of agonistic support may differ when provided to victims or aggressors. Supporting victims may not only protect them, but also limit the escalation of aggression among group members. Our results on Theropithecus gelada showed that support was preferentially directed towards victims and high-ranking individuals provided the highest levels of support. Whereas the support towards the aggressor had no effect in reducing its renewed aggression, it increased the frequency of subsequent conflicts among fellows. The support towards victims significantly reduced subsequent aggression both towards the victim and among other group members. The support was biased towards victims who were unrelated and shared weak bonds with the aggressors. In conclusion, victim support may be a social tool, which intervenes when other mechanisms are less likely to occur such as the case when the opponents are not kin or friends.
The collection of papers presented in this Special Issue is the outcome of a series of workshops on the evolution of play held between 2011 and 2013 and sponsored by the National Institute of Mathematical and Biological Synthesis (NIMBioS) at the University of Tennessee (Knoxville, TN, USA). These workshops were aimed at stimulating a multidisciplinary discussion about one of the most debated and controversial behaviours in the Animal Kingdom. Although neglected for a long time by researchers studying non-human animals, play research seems to be having a new Renaissance and the last ten years have been extremely fruitful in highlighting some important functions and in delineating key correlates of this activity. Obviously, it is impossible to fully represent such a multifaceted topic as play in a handful of papers; however, the articles in this Special Issue bring to light some over-arching themes and together provide innovative perspectives on play.
Play provides children with the opportunity to train in fundamental social skills, including conflict management. Here, we evaluate the management of play, aggressive conflict and reconciliation in 3- to 5-year-old preschool children. 3-year-old children show the highest levels of aggressive conflicts in free play, and do not reconcile their aggressive conflicts in the first months of the preschool year because they still lack social capacities to successfully manage interactions with peers. We found no gender bias in being aggressors or victims, but gender-typed traits were reflected in the expression of aggressiveness in same-sex peers for boys, who rely more on physical contacts than girls. Gender segregation in play is seen only in boys, regardless of age. Our results emphasize the importance of considering play, aggressive conflicts, and reconciliation as a whole, in order to obtain a comprehensive overview of the development of pre- and post-conflict dynamics in humans.
The concept of peace, with its corollary of behaviours, strategies and social implications, is commonly believed as a uniquely human feature. Through a comparative approach, we show how social play in animals may have paved the way for the emergence of peace. By playing fairly, human and nonhuman animals learn to manage their social dynamics in a more relaxed and tolerant way that results in a more effective management of conflicts. We show that play promotes tolerance, cooperation, fairness and reciprocity, which are essential elements of the so-called positive peace. This kind of peace is reached through an evolving process in which individuals continually modify social relationships to attain peaceful coexistence. In conclusion, we assume that the concept of peace has deep biological roots that constitute the basis for more sophisticated cultural constructions.