Reconciliation following aggression in patas monkeys,Erythrocebus patas

Following intra-group aggression, obvious conciliatory displays are absent from the behavioural repertoire of patas monkeys, Erythrocebus patas, while many other Old World primate species show special reconciliation gestures. When 10-min focal-animal samples that began after spontaneous aggression were compared with matched-control samples, captive adult female patas followed up on aggressive interactions, interacting sooner and more often with former opponents during post-conflict observations than during matched-control observations. Almost one-third of post-conflict observations included affiliative behaviour between former opponents, which is termed reconciliation. Matrilineally related opponents were more likely to reconcile with one another than were unrelated animals. No effect of the dominance hierarchy on tendency to reconcile was found. Thus, patas monkeys showed general patterns in post-conflict behaviour that were similar to those seen in other primates previously investigated.     

Reconciliation in the Spotted Hyena (Crocuta crocuta)

Theory predicts that it should often be in the best interests of gregarious animals to repair social bonds damaged by within-group conflict. Indeed, reconciliation in many primates takes the form of affiliative behavior occurring shortly after a conflict. Here we inquired whether reconciliation also occurs among spotted hyenas ( Crocuta crocuta ), gregarious carnivores whose social lives share much in common with those of cercopithecine primates. In a large group of free-living hyenas in Kenya, we used focal animal observations to monitor rates at which various affiliative behaviors occurred before and after dyadic aggressive interactions. An affiliative behavior was identified as having a conciliatory function only if it occurred more frequently after than before fights, and if it was also associated with reduced rates of aggression between former opponents during the post-conflict interval. Of all affiliative behaviors monitored, only two types satisfied both these criteria: greeting behavior and non-aggressive approach. Over 72% of conciliatory behaviors occurred within the first five minutes after a fight, and hyenas reconciled after 14.6% of 698 fights. Mean conciliatory tendency (CT) for individual hyenas was 11.3%. Hyenas exhibited higher CTs when they were recipients (victims) of aggression than when they were aggressors, and they showed higher CTs in interactions with non-kin than with kin. Conciliatory tendencies did not vary with age–sex classes of opponents or with rank distance between opponents . Conciliatory tendency in spotted hyenas fell at the low end of the CT range observed among primates.     

Bonobos Respond to Distress in Others: Consolation across the Age Spectrum

How animals respond to conflict provides key insights into the evolution of socio-cognitive and emotional capacities. Evidence from apes has shown that, after social conflicts, bystanders approach victims of aggression to offer stress-alleviating contact behavior, a phenomenon known as consolation. This other-orientated behavior depends on sensitivity to the other''s emotional state, whereby the consoler acts to ameliorate the other''s situation. We examined post-conflict interactions in bonobos (Pan paniscus) to identify the determinants of consolation and reconciliation. Thirty-six semi-free bonobos of all ages were observed at the Lola ya Bonobo Sanctuary, DR Congo, using standardized Post-conflict/Matched Control methods. Across age and sex classes, bonobos consoled victims and reconciled after conflicts using a suite of affiliative and socio-sexual behaviors including embracing, touching, and mounting. Juveniles were more likely to console than adults, challenging the assumption that comfort-giving rests on advanced cognitive mechanisms that emerge only with age. Mother-reared individuals were more likely to console than orphans, highlighting the role of rearing in emotional development. Consistent with previous studies, bystanders were more likely to console relatives or closely bonded partners. Effects of kinship, affiliation and rearing were similarly indicated in patterns of reconciliation. Nearby bystanders were significantly more likely to contact victims than more distal ones, and consolation was more likely in non-food contexts than during feeding. The results did not provide convincing evidence that bystander contacts served for self-protection or as substitutes for reconciliation. Overall, results indicate that a suite of social, developmental and contextual factors underlie consolation and reconciliation in bonobos and that a sensitivity to the emotions of others and the ability to provide appropriate consolatory behaviors emerges early in development.     

Identifying potential risk situations for humans when removing horses from groups

Removing a horse from its social group may be considered risky, both for the handler and the horse, because other horses can interfere in the catching process. The main aim of this study was to identify where and when these risk situations occur while removing a horse from its group. A potential risk situation was defined by the closeness of loose horses in the group or by any physical contact with them. Whether the number of horses following would be influenced by the social rank of the horse being led out, and whether more horses would follow to the gate when a larger proportion of the group was removed compared to when a single horse was taken out were also investigated.Thirty-two mares (1-2 years) were kept in groups of four. All horses were taken out of their home paddock twice alone (64 tests) and twice with a companion (32 tests). One handler (or two handlers when two horses were removed) was asked to approach (phase 1) and catch the target horse (phase 2), walk it to the centre of the paddock and remain stationary at a post for 30 s (phase 3), walk to the paddock entrance (phase 4) and through the gate (phase 5). The number of horses following, and the number of loose horses in proximity (<2 m, 2-5 m) to the target horse and handler was estimated, and horse-horse and horse-human interactions were recorded continuously for the five scoring phases.Significantly more loose horses were within 2 m of a single target horse during the phases approach (mean ± SD: 1.5 ± 0.8), catch (1.6 ± 0.9) and post (1.7 ± 0.7) than during walk (1.0 ± 0.5) and gate (1.1 ± 0.6). Rank did not influence the number of horses following to the gate (high rank: 2.4 ± 0.7; lower rank: 2.0 ± 1.0; P = 0.396) and interactions between horses were rare. A greater proportion of the loose horses followed when two horses (0.9 ± 0.2) were removed compared to when a single horse (0.7 ± 0.3) was taken out (P = 0.011).In conclusion, maintaining a distance to other horses in the group by reducing the time being relatively stationary, so giving loose horses fewer chances to approach, is likely to contribute to improved handler's safety. Removing a small proportion of the group may also decrease the probability of the other horses following.     

Post-Conflict Affiliation in Barbary Macaques is Influenced by Conflict Characteristics and Relationship Quality, but Does Not Diminish Short-Term Renewed Aggression

Many group living primates have evolved mechanisms to repair their social relationships after conflicts ('reconciliation'). We analysed the post-conflict behaviour of female Barbary macaques, Macaca sylvanus , living in the enclosure 'La Forêt des Singes' at Rocamadour, France. Based on a sample of 914 conflicts, we investigated whether relationship (kinship, rank, affiliation, support and sex) and conflict characteristics (conflict intensity, context and duration) affected the quality and frequency of affiliative post-conflict interactions. Thirty-two per cent of all conflicts were followed by post-conflict affiliation. Rates of socio-positive interactions and support were better predictors of post-conflict affiliation than kinship or rank. Short conflicts were followed by post-conflict affiliation relatively more frequently, after a shorter latency, but only briefly, and such interactions were initiated by both parties equally frequently. The majority of affiliative post-conflict interactions occurred immediately after the end of the conflict. In sum, female Barbary macaques invest more in post-conflict affiliation with valuable partners, and they modulate their post-conflict behaviour in relation to conflict characteristics. Remarkably, affiliative post-conflict interactions increased the short-term probability of renewed aggression by the former aggressor to 16% compared with 9% for conflicts that were not followed by affiliative behaviour. Such renewed aggression after post-conflict affiliation occurred particularly frequently among females and after conflicts over food, suggesting that post-conflict affiliation sometimes falsely lures the former victim to stay in the vicinity, even at the risk of receiving renewed aggression.     

Post-conflict Behaviour of Wild Olive Baboons. II. Stress and Self-directed Behaviour

Previous studies indicate that the proximate function of post-conflict affiliative interaction among primates is to reduce a victim's uncertainty about its opponent's future behaviour: the ‘uncertainty reduction hypothesis’ (Aureli & van Schaik 1991; Ethology, 89 , 101–114). This study confirms and extends these results, demonstrating that they are neither a product of captivity nor specific to macaques: both victims and initiators of aggression in a large group of wild olive baboons exhibited elevated rates of self-directed behaviour (SDB) - scratching, autogrooming, body-shaking and yawning - in a 10-min post-conflict period. During this period, they were more likely to receive further aggression. Reconciliation reduced both SDB and the incidence of further aggression. However, reconciliation only reduced SDB among individuals involved in conflicts in which both parties exchanged aggression. It is suggested that aggressors in unilateral conflicts were aroused rather than uncertain and that their victims' lack of control over post-conflict interactions (which tended to be initiated by their opponents) prevented them from benefiting from reconciliation in the same fashion as longtailed macaque victims, which frequently initiated reconciliation.     

Testing the function of reconciliation and third-party affiliation for aggressors in hamadryas baboons (Papio hamadryas hamadryas)

In social groups, agonistic conflicts can have different negative consequences. Several post-conflict interactions have been suggested as post-conflict management behaviors to mitigate those negative effects. In this study, we investigated the function of two post-conflict behaviors--reconciliation and aggressor-initiated third-party affiliation--on the aggressor's levels of post-conflict anxiety and aggression in a large colony of hamadryas baboons. We also examined variation in the aggressor's levels of post-conflict anxiety as a function of relationship quality between the opponents as predicted by the Integrated Hypothesis. We found that after conflicts hamadryas baboon aggressors showed increased rates of anxiety-related behaviors and that they were also more likely to be involved in renewed aggressive interactions. Although both reconciliation and aggressor-initiated third-party affiliation reduced the probability of receiving post-conflict aggression, only reconciliation reduced the rates of anxiety-related behaviors, suggesting that the aggressors' post-conflict anxiety might be owing mainly to the damage that the conflict causes to their relationship with the victim. Furthermore, aggressor's rates of post-conflict anxiety were higher after conflicts with individuals with whom they had a high-quality relationship, supporting the idea that levels of post-conflict anxiety mediate the occurrence of reconciliation depending on the quality of the relationship with former opponent as predicted by the Integrated Hypothesis.     

The effect of inter-opponent distance on the occurrence of reconciliation in stumptail (Macaca arctoides) and rhesus macaques (Macaca mulatta)

Several studies have shown that affiliative contact between opponents increases after conflicts in a number of primate species. This study investigated the effect of inter-opponent distance on the occurence of reconciliation in stumptail and rhesus macaques. Both species were represented by multi-male, multi-female groups housed in large outdoor compounds. Ten-minute focal animal observations during post-conflict (PC) and matched control (MC) samples were collected in which affiliative interactions and the inter-opponent distance at the beginning of each sample were recorded. A total of 251 and 561 PC-MC opponent pairs were obtained for stumptail and rhesus macaques, respectively. Inter-opponent distance was smaller in PC than in MC observations for both stumptail and rhesus macaques. Conciliatory tendency varied as a function of the initial PC-MC inter-opponent distance. In particular, the closer opponents were in PC compared to MC periods, the more likely they were to reconcile. When the inter-opponent distance was the same in PC and MC periods the conciliatory tendency of both species was notably reduced. These findings have implications for the estimation of conciliatory tendency and its use in comparative studies.     

Aggression and Reconciliation in Cebus capucinus

Most data relating to aggressive and conciliatory behaviors are from Old World primates. We recorded agonistic interactions and post-conflict behaviors in a group of 12 white-faced capuchins (Cebus capucinus). After a conflict, we followed the aggressee as the focal individual during a 10-min postconflict period. We also conducted matched-control observations on the same individual. Conflicts involving physical contact were significantly bidirectional, and conflicts without physical contact were preferably unidirectional. Reconciliation was not be demonstrated at the group level. However, reconciliation occurred in kin and non-kin male/female dyads: their conciliatory tendencies were 48.1% and 21.2%, respectively. White-faced capuchins reconciled mainly during the first minutes after the end of the conflict. In kin and non-kin male/female dyads, selective attraction occurred, and aggressors were more likely to initiate affiliative contacts than aggressees. Hold-bottom and mount while emitting loud vocalizations were the most characteristic behaviors of reconciliation. Possible links may exist between aggressive and conciliatory patterns and other social variables.     

Postconflict third-party affiliation in rooks, Corvus frugilegus

Conflict features in the lives of many animal species and induces social stress mediated by glucocorticoid hormones [1]. Postconflict affiliation, between former opponents (reconciliation) or between former opponents and a bystander (third-party affiliation), has been suggested as a behavioral mechanism for reducing such stress [2], but has been studied almost exclusively in primates [3]. As with many primates, several bird species live in social groups and form affiliative relationships [4]. Do these distantly related animals also use affiliative behavior to offset the costs of conflict? We studied postconflict affiliation in a captive group of rooks. Unlike polygamous primates, monogamous rooks did not reconcile with former opponents. However, we found clear evidence of third-party affiliation after conflicts. Both initiators and targets of aggression engaged in third-party affiliation with a social partner and employed a specific behavior, bill twining, during the postconflict period. Both former aggressors and uninvolved third parties initiated affiliative contacts. Despite the long history of evolutionary divergence, the pattern of third-party affiliation in rooks is strikingly similar to that observed in tolerant primate species. Furthermore, the absence of reconciliation in rooks makes sense in light of the species differences in social systems.     

Peace-Making in Marsupials: The First Study in the Red-Necked Wallaby (Macropus rufogriseus)

The issue of reconciliation has been widely investigated in many eutherian mammal species. Nevertheless, no data are available for marsupial mammals. Indeed, the majority of reports focus on group dynamics from an ecological and reproductive perspective, but no study has investigated them from a social point of view. We observed the red-necked wallaby colony (Macropus rufogriseus) hosted at the Tierparc Zoo Berlin (Germany) and collected data on aggressive and post-conflict interactions between group members. We found that the phenomenon of reconciliation is present in the study species (mean group CCT 27.40% ±8.89% SE). Therefore, we demonstrated, for the first time, the occurrence of reconciliation in a gregarious marsupial mammal. Post-conflict reunion was not affected by the relationship quality between individuals (friendship or kinship) but it was fine-tuned according to the aggression intensity. For example, low intensity conflicts were reconciled whereas high intensity ones were not. Reconciliation reduced anxiety-related scratching in both of the former opponents and limited further attacks towards the victim during the post-conflict period. These findings suggest that the red-necked wallaby, like many eutherian species, can evaluate the costs of reconciliation and engage in peace-making behavior in the right contexts, in order to maximize its pay-offs.     

Epistasis among Deleterious Mutations in the HIV-1 Protease

A central goal in molecular evolution is to understand how genetic interactions between protein mutations shape protein function and fitness. While intergenic epistasis has been extensively explored in eukaryotes, bacteria, and viruses, intragenic epistatic interactions have been insufficiently studied. Here, we employ a model system in which lambda phage fitness correlates with the enzymatic activity of human immunodeficiency virus type 1 (HIV-1) protease to systematically determine the epistatic interactions between intragenic pairs of deleterious protein substitutions. We generated 114 genotypes of the HIV-1 protease, each carrying pairs of nucleotide substitution mutations whose separated and combined deleterious effects on fitness were then determined. A high proportion (39%) of pairs displayed lethality. Several pairs exhibited significant interactions for fitness, including positive and negative epistasis. Significant negative epistatic interactions predominated (15%) over positive interactions (2%). However, the average ± SD epistatic effect, ē = 0.0025 ± 0.1334, was not significantly different from zero (p = 0.8368). Notably, epistatic interactions, regardless of epistatic direction, tend to be more frequent in the context of less deleterious mutations. In the present study, the high frequencies of lethality and negative epistasis indicate that the HIV-1 protease is highly sensitive to the effects of deleterious mutations. Therefore, proteins may not be as robust to mutational change as is usually expected.     

Study of reconciliation in anubis baboons

The study of post-conflict reconciliation in corral living anubis baboons was carried out. It was established that more than third part of the all the conflicts were followed with reconciliation, and the mean value for the frequency of reconciliation tendency was 27.3 +/- 2.4. The frequency of reconciliation in different categories of conflicting pairs of animals was comparable. 75% of cases of reconciliation occurred during the first 2 minutes after the conflict. Use of definite behavioral patterns by the individuals for demonstration of reconciliation depended on sex of the participants and on their role in the conflict. Differences in the indices of reconciliation tendency in high and low rank monkeys were found.     

Resolution of aggressive conflicts by immature long-tailed macaques Macaca fascicularis

The behaviour following aggressive interactions differed from the behaviour following friendly or neutral control interactions among unrelated immature male Macaca fascicularis. Former opponents interacted again sooner and more often after aggression than after a friendly or neutral encounter. The higher rate did not reflect a general increase in social activity. The behaviour characterizing encounters between former opponents also differed in the two situations, with more affiliative interactions postconflict. In both situations, however, most interactions between former opponents were initiated by the higher-ranking aggressor. This pattern of interactions between former opponents is interpreted as a repair mechanism for relationships strained by aggression (i.e. reconciliation). A similar pattern of interactions was found for related animals, though it occurred more rarely than among non-kin.     

Postconflict Behavior of Spectacled Leaf Monkeys (Trachypithecus obscurus). II. Contact with Third Parties

We studied the postconflict interactions with group members other than the former opponent in two groups of spectacled leaf monkeys. We found no evidence of redirection of aggression towards other group members. Victims and aggressors sought affiliative contacts with uninvolved third parties. There was no evidence for consolation—affiliative contact initiated by an uninvolved third party, directed towards victims of aggression—in either group when all affiliative behaviors were considered. However, embracing was a characteristic first-contact interaction between individuals involved in aggression and third parties. This finding mirrors the results concerning reconciliation in spectacled leaf monkeys. Accordingly, embracing may be a true consolatory behavior in this species. When contacts with third parties occurred before or in the absence of reconciliation, the timing of such contacts fell within the time window during which reconciliation normally occurs. These contacts also resulted in affiliation levels twice that of baseline levels, supporting the idea that these contacts may function as a form of substitute reconciliation. We discuss these results in light of recent theories concerning postconflict behavior in primates.     

On operationally defining reconciliation

Post-conflict reconciliatory behavior has been reported to occur with variable frequencies in different primate groups and species. Because different investigators have used different criteria to operationalize reconciliation, however, it is possible that the variation reported merely reflects different methods of study. To compare different groups and species in a meaningful way, an accurate operationalization of reconciliation is necessary. This study explores the correlation between operationally defined reconciliation (what observers recognize, such as friendly reunion) and functional reconciliation (behavior that restores a dyadic social relationship) in a group of captive long-tailed macaques, using results from an experiment originally undertaken to demonstrate the function of friendly reunions in restoring dyadic tolerance after aggression. In dyads of unrelated animals, reunions were equally effective in restoring tolerance whether they involved body contact, overt friendly gestures, or mere proximity. Classification of post-conflict reunions as “reconciliations” depends on comparisons with control observations; these comparisons have been carried out in several ways. Comparisons using the “n-minute rule” missed functional reconciliations, whereas those based on the “post-conflict/matched-control rule” appeared to lead to more accurate classification of functional reconciliations. Post-conflict reunions were equally effective in restoring tolerance whether they were initiated by the original aggressor or by the victim. An accurate operational definition of reconciliation, not a conservative one, is prerequisite to comparisons of the frequency of this behavior, and depends on empirical verification. This study suggests specific guidelines for an operational definition based on such verification. © 1993 Wiley-Liss, Inc.     

Do Ringtailed lemurs (Lemur catta) reconcile in the hour post-conflict?: A pilot study

A previous study byKappeler (1993) showed that no reconciliation occurred in the ringtailed lemur (Lemur catta). Like the majority of studies dealing with reconciliation, the post-conflict period lasted 10 minutes. An identical study using a 70-min post-conflict period was conducted on one of the same semi-free ranging group studied six years earlier byKappeler. Results showed that individuals who never interacted within 10 min did engage in friendly interactions in the longer lasting postconflict period.     

Ravens reconcile after aggressive conflicts with valuable partners

Reconciliation, a post-conflict affiliative interaction between former opponents, is an important mechanism for reducing the costs of aggressive conflict in primates and some other mammals as it may repair the opponents' relationship and reduce post-conflict distress. Opponents who share a valuable relationship are expected to be more likely to reconcile as for such partners the benefits of relationship repair should outweigh the risk of renewed aggression. In birds, however, post-conflict behavior has thus far been marked by an apparent absence of reconciliation, suggested to result either from differing avian and mammalian strategies or because birds may not share valuable relationships with partners with whom they engage in aggressive conflict. Here, we demonstrate the occurrence of reconciliation in a group of captive subadult ravens (Corvus corax) and show that it is more likely to occur after conflicts between partners who share a valuable relationship. Furthermore, former opponents were less likely to engage in renewed aggression following reconciliation, suggesting that reconciliation repairs damage caused to their relationship by the preceding conflict. Our findings suggest not only that primate-like valuable relationships exist outside the pair bond in birds, but that such partners may employ the same mechanisms in birds as in primates to ensure that the benefits afforded by their relationships are maintained even when conflicts of interest escalate into aggression. These results provide further support for a convergent evolution of social strategies in avian and mammalian species.     

Changes in cortisol release and heart rate and heart rate variability during the initial training of 3-year-old sport horses

Based on cortisol release, a variety of situations to which domestic horses are exposed have been classified as stressors but studies on the stress during equestrian training are limited. In the present study, Warmblood stallions (n = 9) and mares (n = 7) were followed through a 9 respective 12-week initial training program in order to determine potentially stressful training steps. Salivary cortisol concentrations, beat-to-beat (RR) interval and heart rate variability (HRV) were determined. The HRV variables standard deviation of the RR interval (SDRR), RMSSD (root mean square of successive RR differences) and the geometric means standard deviation 1 (SD1) and 2 (SD2) were calculated. Nearly each training unit was associated with an increase in salivary cortisol concentrations (p < 0.01). Cortisol release varied between training units and occasionally was more pronounced in mares than in stallions (p < 0.05). The RR interval decreased slightly in response to lunging before mounting of the rider. A pronounced decrease occurred when the rider was mounting, but before the horse showed physical activity (p < 0.001). The HRV variables SDRR, RMSSD and SD1 decreased in response to training and lowest values were reached during mounting of a rider (p < 0.001). Thereafter RR interval and HRV variables increased again. In contrast, SD2 increased with the beginning of lunging (p < 0.05) and no changes in response to mounting were detectable. In conclusion, initial training is a stressor for horses. The most pronounced reaction occurred in response to mounting by a rider, a situation resembling a potentially lethal threat under natural conditions.     

Postconflict Affiliation Between Former Opponents in Macaca thibetana on Mt. Huangshan, China

We describe basic patterns of postconflict affiliation between former opponents within a group of wild, provisioned Tibetan macaques Macaca thibetana on Mt. Huangshan, China. Like most primates studied to date, Tibetan macaques reconciled, i.e., overall they engaged in affiliative interaction with opponents at higher rates immediately after an aggressive conflict than at other times. Probabilities of affiliation were enhanced ≤30 s after the end of hostilities. However when we examined sex partner combinations separately, we found unequivocal evidence for reconciliation only for male-male dyads. Tolerant interaction among other partner combinations apparently was not disrupted after a conflict, presumably obviating the need to reconcile. One aspect of reconciliation among males was consistent with other indications of a despotic dominance style: aggressors initiated a higher proportion of affiliative interactions after a conflict than at other times. Another aspect of reconciliation was more typical of relaxed dominance styles: males used specialized behaviors (embraces and same-sex mounts) disproportionately to reconcile. We also found inconsistent evidence for the valuable relationship hypothesis; probabilities of reconciliation were enhanced for male-male dyads with the closest affiliative relationships, but not for those that displayed the most tolerance or mutual agonistic support. We discuss reconciliation and other aspects of conflict management among males in the context of a group with nearly even sex ratios and high male-male mating competition.