Conciliatory Tendency Research Articles

A comparative study of conflict resolution in macaques: insights into the nature of trait covariation

Conflict resolution is an essential component of primate sociality that has been studied extensively within primate social groups, but few studies have examined how conflict resolution behaviours covary at evolutionary scales. We assembled a standardized data set on social interactions of sexually mature females to analyse patterns of conflict resolution in 15 groups of nine macaque species. Between-group comparisons revealed no significant difference in nonkin reconciliation levels between groups of the same species, whereas substantial interspecific differences were found. We tested for associations between four behavioural traits involving reconciliation and dominance asymmetry that play a central role in primate social systems. Regression analyses using group values indicated that these traits (conciliatory tendencies, proportions of explicit reconciliatory contacts, kin bias and levels of counteraggression) exist as an integrated suite of characters. We found strong phylogenetic signal in most traits, which further indicates that they evolved during the adaptive radiation of macaques. Using the method of independent contrasts, relationships between conciliatory tendencies and proportions of explicit reconciliatory contacts and between kin bias and levels of counteraggression remained consistent after controlling for phylogeny. This reveals that evolutionary change in one trait leads to correlated changes in other traits. Collectively, these results show how comparative studies of detailed behavioural interactions can be used to elucidate primate socioecology.

Sex Differences in Reconciliation and Post‐Conflict Anxiety in Bonnet Macaques

AbstractRates of reconciliation vary widely between different types of opponents, and post‐conflict anxiety has been proposed to mediate individual variation in reconciliation rates. We investigated the form and function of reconciliation in a wild, provisioned group of bonnet macaques (Macaca radiata) with the prediction that sex differences in post‐conflict anxiety would be associated with sex differences in conciliatory tendency. Individuals in the study group had a conciliatory tendency of 29.3%. Victims avoided their former opponents at a higher rate following aggression than during matched‐control samples, and reconciliation decreased the rate of avoidance. Although victims showed a higher rate of anxiety‐related behavior than did aggressors, anxiety‐related behavior was elevated after aggression and reduced following reconciliation in both victims and aggressors. Female–female opponents showed higher rates of anxiety‐related behavior before reconciliation than they did following unreconciled aggression. In contrast, male–male and female–male opponents showed increased anxiety‐related behavior following aggression regardless of the occurrence of reconciliation. Moreover, female–female opponents had a higher conciliatory tendency than did female–male opponents. The elevated post‐conflict anxiety shown by female–female opponents before reconciliation, along with their high conciliatory tendency, suggests that post‐conflict anxiety promotes reconciliation. In sum, the sex differences in post‐conflict behavior found in this study support the hypothesis that variation in post‐conflict anxiety mediates differential rates of reconciliation.

Conflict Resolution in Chimpanzees and the Valuable-relationships Hypothesis

Reconciliation, or peaceful postconflict interaction, can restore the usual pattern of interaction between social partners after open conflict has disrupted it—i.e., it can resolve conflicts. Researchers have documented reconciliation in >20 primate species, but the tendency to reconcile typically varies among dyads and dyad classes. The valuable-relationships hypothesis proposes that differences in the value of social relationships account for much of this variation. Value depends on how likely partners are to act in ways that benefit each other, where the benefits are ultimately direct or indirect increases in fitness. Researchers have responded to studies that have tested predictions of the hypothesis with extensive, if not universal, support. For example, kin show higher conciliatory tendencies than nonkin in many species, and conciliatory tendencies between unrelated females are high in several cercopithecines in which nonkin agonistic support is important for rank acquisition and maintenance. However, most of the support is indirect, because we lack direct evidence on the link between assays of relationship value and fitness. Also, some studies have methodological weaknesses, e.g., analyses based on pooled data and insufficient sample sizes. I review evidence in favor of the hypothesis with special attention to studies that come closest to providing evidence for predicted fitness effects. I also present new data on postconflict interactions between adult male chimpanzees at Ngogo that show how often pairs of males formed coalitions and how much time they spent grooming influenced the likelihood that they would reconcile after conflicts, and that allies were particularly likely to reconcile and to do so by grooming each other. The most important future research direction is to integrate detailed data on conflict management, analyzed at the level of dyads, with long-term data on reproductive success, such as that now available from several study sites, on the same populations.

Seasonal Effects on Reconciliation in Macaca fuscata yakui

Dietary composition may have profound effects on the activity budgets, level of food competition, and social behavior of a species. Similarly, in seasonally breeding species, the mating season is a period in which competition for mating partners increases, affecting amicable social interactions among group members. We analyzed the importance of the mating season and of seasonal variations in dietary composition and food competition on reconciliation in wild female Japanese macaques (Macaca fuscata yakui) on Yakushima Island, Japan. Yakushima macaques are appropriate subjects because they are seasonal breeders and their dietary composition significantly changes among the seasons. Though large differences occurred between the summer months and the winter and early spring months in activity budgets and the consumption of the main food sources, i.e., fruits, seeds, and leaves, the level of food competition and conciliatory tendency remained unaffected. Conversely, conciliatory tendency is significantly lower during the mating season than in the nonmating season. Moreover, conciliatory tendency is lower when 1 or both female opponents is in estrous than when they are not. Thus the mating season has profound effects on reconciliation, whereas seasonal changes in activity budgets and dietary composition do not. The detrimental effects of the mating season on female social relationships and reconciliation may be due to the importance of female competition for access to male partners in multimale, multifemale societies.

Differential Functional Variability of Serotonin Transporter and Monoamine Oxidase A Genes in Macaque Species Displaying Contrasting Levels of Aggression-Related Behavior

Functional allelic variation in the transcriptional control region of the serotonin transporter and monoamine oxidase A genes has been associated with anxiety- and aggression-related behavior in humans and, more recently, in nonhuman primates. Here, we have genotyped these polymorphic regions in seven species of the genus Macaca. Macaques exhibit exceptional inter-species variation in aggression-related social behavior as illustrated by recent studies showing overlapping patterns of aggression-based social organization grades and macaque phylogeny. We cloned and sequenced two new alleles of the serotonin transporter gene-linked polymorphic region in Barbary and Tibetan macaques. In addition, we observed that species displaying tolerant societies, with relaxed dominance and high levels of conciliatory tendency, were monomorphic for both the serotonin transporter gene and, with the exception of Tonkean macaques, the monoamine oxidase A gene. In contrast, those species known to exhibit intolerant, hierarchical and nepotistic societies were polymorphic at one or more of these loci. Rhesus (M. mulatta), the most intolerant and hierarchical species of macaques, showed the greatest degree of allelic variation in both genes. Additional investigation of a polymorphic repeat in exon III of the dopamine receptor D4 as well as a repeat/single nucleotide polymorphism in the 3' untranslated region of the dopamine transporter which have both been implicated in the modulation of complex behavior failed to reveal a relationship between allelic variability and social organization grade. Taken together, these findings suggest that genetic variation of serotonergic neurotransmission may play an important role in determining inter-species differences in aggression related behavior in macaques.

Postconflict Behavior Among Male Japanese Macaques

Reconciliation was first described more than 20 years ago. Since then, it has been observed in many mammals (mainly primates) but data on postconflict behavior among males are still scarce because they usually aggressively compete for mating partners, rarely maintain amicable relationships with one another. Accordingly, reconciliation is expected to occur at low rates. Although this is true for Japanese macaque males, the subspecies on Yakushima Island (Macaca fuscata yakui) seems to represent an exception as grooming among males occurs often. We analyzed postconflict behavior among them and discuss the possible factors that may favor the occurrence of grooming and reconciliation. Selective attraction between former opponents—reconciliation—occurred soon after conflicts. Consolation—affiliative interactions between a focal animal and group members other than the former opponents occurring earlier in PCs than in MCs—was absent among males. Conciliatory tendency is higher for Yakushima macaque males (0.31) versus that in studies on the other subspecies Macaca fuscata. We discuss differences in the behavioral ecology of the 2 subspecies, the ecological and social factors that may favor the occurrence of reconciliation, and the possible benefits that males gain from grooming exchange and reconciliation.

Reconciliation pattern after aggression among Japanese preschool children

Using an ethological observation method (the PC-MC comparison method), this study investigated patterns of reconciliation after aggression among Japanese preschool children, focusing on factors that influenced its occurrence or acceptance, as well as on strategies and function. There were several factors among four-year-olds that facilitated reconciliatory attempts and acceptance, such as proximity after the aggression; among three-year-olds there were no such factors. Depending on the situation during and after aggression, children used 'explicit' (e.g., apologizing, compromising, and offering objects) and 'implicit' (e.g., being friendly, talking without apologizing, and touching the opponent gently) reconciliatory strategies. Reconciliation occurred more often among friends than among non-friends, particularly among four-year-olds. However, after considering the baseline affiliation level, the conciliatory tendency among non-friends was higher than that among friends in four-year-olds. Victims' self-directed behavior (SDB) - a behavioral index of stress - was elevated following aggression, but decreased following reconciliation. This suggests that reconciliation functions to reduce the post-conflict stress suffered by the targets of aggression.

Reconciliation in wild white-faced capuchins (Cebus capucinus)

The likelihood of reconciliation (defined as preferential peaceful contact among former opponents following conflicts) has been predicted to vary positively with relationship value and compatibility, and negatively with relationship security. Long-term data on wild white-faced capuchins (Cebus capucinus) indicate that dyads consisting of an adult female and an alpha male have high value and compatibility, but low security. Two studies of C. capucinus postconflict (PC) behavior were carried out at Lomas Barbudal Biological Reserve, Costa Rica. One study consisted of 30-min PC and matched control (MC) follows. The second study extracted PC and MC periods from long follows, yielding PC/MC periods averaging 105 min. In study 2, but not study 1, significantly more PC/MC pairs were attracted (former opponents affiliated with each other sooner in the PC period than in the MC period) than were dispersed (former opponents affiliated with each other sooner in the MC period than in the PC period). Reconciliation in study 2 could not be explained as a by-product of former opponents' tendency to seek affiliative contact with conspecifics generally, or of the spatial proximity of opponents following conflicts. Attempted reconciliation was less likely to be followed by renewed aggression when reconciliation attempts were delayed following conflicts. The data were insufficient for a formal test of differences in conciliatory tendency (the difference between the number of attracted and dispersed PC/MC pairs, divided by the total number of pairs) among dyad types to be conducted.

Dominance Style Among Macaca thibetana on Mt. Huangshan, China

The dominance style concept has proven useful for understanding covariation patterns in relationship qualities, particularly among macaques. However, the dominance styles of many macaques, including Tibetan macaques (Macaca thibetana), have not been examined in detail. We describe patterns of bidirectionality of aggression, postconflict affiliation and kin bias in a group of wild, but provisioned Tibetan macaques over a 2-yr period in order make an initial assessment of their dominance style. Bidirectional aggression, including percentage of counteraggression (1.9%), and conciliatory tendencies (6.4%) were consistently low across partner combinations, seasons and locations (forest vs. provisioning area). In addition, females consistently displayed high levels of kin bias in affiliation and tolerance. Compared with macaque species with better known dominance styles, the Tibetan data generally fell within the range for despotic species and outside the range for relaxed species. Although other researchers have tentatively classified them as tolerant or relaxed, we conclude that Tibetan macaques display a despotic dominance style. This conclusion poses complications to explanations based both on phylogenetic inertia and socio-ecological models.

Conflict and post-conflict behavior in a small group of chimpanzees.

Chimpanzee research plays a central role in the discussions of conflict negotiation. Reconciliation, or the attraction and affiliation of former opponents following conflict, has been proposed as a central element of conflict negotiation in chimpanzees and various other taxa. In an attempt to expand the database of chimpanzee conflict resolution, conflict and post-conflict behavior were recorded for a small group of socially housed chimpanzees at the Chimpanzee and Human Communication Institute, at Central Washington University. Data were collected over six 6-week periods between 1997 and 2000, for a total of 840 hours of observation, resulting in a substantial post-conflict (PC) and matched control (MC) data set. The data demonstrate this group's tendencies to maintain visual contact and closer proximity after conflicts. Dyadic corrected conciliatory tendencies ranged between 0 - 37.5% and averaged 17.25% across all dyads. Individual corrected conciliatory tendencies ranged between 5.8 and 32%. The results of this study combined with recent publications on captive and free-ranging chimpanzee post-conflict behavior suggest that variation in post-conflict behavior may be important to our understanding of chimpanzee conflict negotiation, and may also have implications for the design and management of captive chimpanzee enclosures and social groups, respectively.

Counter aggression and reconciliation in Assamese macaques (Macaca assamensis)

Patterns of aggressive and affiliative behavior, such as counter aggression and reconciliation, are said to covary in the genus Macaca; this is referred to as the systematic variation hypothesis. These behavior patterns constitute a species dominance style. Van Schaik's [1989] socioecological model explains dominance style in macaques in terms of within- and between-group contest competition. Dominance style is also said to correlate with phylogeny in macaques. The present study was undertaken to examine phylogenetic and socioecological explanations of dominance style, as well as the systematic variation hypothesis. We collected data on counter aggression and reconciliation from a habituated group of Assamese macaques (Macaca assamensis) at the Tukeswari Temple in Assam, India. The proportion of agonistic episodes that involved counter aggression was relatively low. Counter aggression, however, occurred more often among males than among females, and it was most common when females initiated aggression against males. The conciliatory tendency for this group of Assamese macaques was 11.2%. The frequency of reconciliation was low for fights among males and for fights among females, but reconciliation was particularly rare for opposite-sexed opponents. Female social relationships were consistent with the systematic variation hypothesis, and suggest a despotic dominance style. A despotic dominance style in Assamese macaques weakens the correlation between dominance style and phylogeny in macaques, but it is not inconsistent with the socioecological model. Male-female relationships were not well explained by the despotic-egalitarian framework, and males may well have more tolerant social relationships than do females. Sex differences need to be considered when categorizing species according to dominance style.

Reconciliation in Captive Chimpanzees: A Reevaluation with Controlled Methods

Affiliative postconflict reunions—reconciliations—of former opponents were first demonstrated in the chimpanzees at the Arnhem Zoo. Since then methods have been considerably refined, and reconciliation has been demonstrated in a large number of primates and also some gregarious nonprimates. This study, conducted with a different captive group, is the first to use the revised methodology with chimpanzees. We analyzed a total of 297 agonistic conflicts with the PC–MC method: we observed focal individuals for 15 min after a conflict and during matched control observations the next day. The mean conciliatory tendency of the 16 chimpanzees was 41%, with a range in different age-sex classes of 58% (among adult females) to 19% (among adult vs. immature males). After conflicts, former opponents were selectively attracted to one another. Preferential contact with previous opponents persisted when activity level during matched controls was controlled for statistically. Opponents that were frequent grooming partners reconciled more frequently, but the frequency of agonistic support had no such effect. Our findings thus confirm the existence of reconciliation in chimpanzees, which show one of the highest conciliatory tendencies among primate species.

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.

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.

Post‐Conflict Affiliation in Two Captive Groups of Black‐and‐White Guereza Colobus guereza

AbstractPost‐conflict affiliation was studied in two captive groups of black‐and‐white guereza (Colobus guereza), a folivorous, arboreal species which lives in harems. The overall level of aggression was low and each individual was involved in only 0.054 aggressive interactions per hour. After 132 aggressive interactions observed during 364 h, former antagonists were found to seek each other out selectively and exchange affiliative behaviours. The first affiliative behaviour was likely to occur within the first minute after the end of the conflict. The post‐conflict affiliative behaviours most often seen were proximity, social grooming, embrace, reciprocal low‐intensity mouth‐opening, groom present and gentle hand touch, in descending order. The pattern of post‐conflict affiliation is thus similar to that observed in most other primate species studied. One notable exception seems to be the relatively high proportion of conflicts after which former opponents continue to remain within arm's reach (in 1/3 of the conflicts). If these instances of remaining‐in‐proximity were excluded, the corrected conciliatory tendency according to Veenema et al. (1994, Behav. Proc. 31, 29–38) was 45% (60% if they were included).

Post-conflict affiliation in common marmosets (Callithrix jacchus jacchus).

Post-conflict (PC) affiliation has been demonstrated in a number of Old World monkeys and apes, but very little is known about the occurrence of the phenomenon in New World monkeys. This study examined 282 PC interactions after spontaneous conflicts around feeding time in two family groups (N = 12) of captive common marmosets, Callithrix jacchus jacchus. We found an overall corrected conciliatory tendency of 31%. Selective attraction was seen: former opponents met significantly more often in PCs than in matched controls (MCs) (27% and 16%, respectively). There was no difference in the occurrence of PC affiliation between dyads consisting of parent-offspring constellations compared to offspring-offspring constellations. PC affiliative behaviors were seen in the first three minutes following conflict termination, and consisted mainly of proximity, play invitations, and food transfer. Notably, former opponents remained within arm's reach after 17% of conflicts. Affiliation was more likely to follow after conflicts involving play issues. The functional importance of the PC affiliation in marmosets remains to be examined.

Impaired reconciliation in rhesus macaques with a history of early weaning and disturbed socialization.

An attempt had been made to create five social groups from rhesus macaques with a history of early separation from their mothers, early weaning and hand feeding and, in most cases, previous housing in single cages. We investigated the exchange of affiliative behaviours after an aggressive encounter and selective attraction to the former opponent, a phenomenon previously well described in rhesus monkeys and called reconciliation. Evidence for reconciliation was only found in one of the five groups studied (corrected conciliatory tendency=13%). This group consisted of younger animals that had, at least temporarily, been living together after separation from their mothers. In the other groups studied, containing animals with a varied background, aggressive interactions were not followed by affiliative behaviours or attraction between former opponents. Our results indicate that the use of reconciliatory behaviours in adult monkeys is dependent upon social training. Lack of functional reconciliation might be one of the explanations to the severe and uncontrolled aggression previously found in groups of rhesus macaques created from animals with disturbed early socialization.

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.

Reconciliation patterns among stumptailed macaques: a multivariate approach

This study focused on two aspects of the dynamics of reconciliation in stumptailed macaques, Macaca arctoides . First, we investigated the combined effects of multiple variables (i.e. sex, age, rank, conflict intensity, outcome, or number of participants, interopponent distance, kinship and friendship) on the occurrence of reconciliation. Second, we investigated whether opponents used different behaviour patterns in their postconflict reunions depending on the characteristics of their conflicts or their relationship with their opponents. We studied a multimale, multifemale group of 38 stumptailed macaques housed in a large outdoor compound. Three types of data were collected: (1) instantaneous scan sampling of contact sitting to infer ‘friendship’; (2) ad libitum data on bared-teeth and teeth-chattering displays to infer dominance rank; (3) 10-min focal observations during postconflict (PC) and matched control (MC) periods in which we recorded interopponent distance at the beginning of the observation and all aggressive and affiliative behaviours between former opponents. Our study confirmed the high conciliatory tendency of stumptailed macaques previously reported for other groups. A stepwise logistic regression revealed that initial interopponent distance in PC, friendship and kinship were the only factors that independently contributed to explain the occurrence of reconciliation. Two main clusters of postconflict behavioural patterns emerged: allogrooming+contact sitting and sociosexual behaviours (e.g. hold-bottom). It is hypothesized that postconflict allogrooming and contact sitting may be used for the maintenance of valuable relationships, whereas sociosexual behaviours may be used more indiscriminately by any pair of opponents as a buffering mechanism to prevent immediate recurrence of aggression.

Post‐conflict Behaviour of Wild Olive Baboons. I. Reconciliation, Redirection and Consolation

AbstractObservations of post‐conflict interactions have provided important insights into primate social organization. In this study, the nature and determinants of post‐conflict behaviour in a troop of wild olive baboons, Papio anubis, were investigated. Reconciliation was observed among all age‐sex classes, occurring at a rate consistent with a relatively intolerant dominance style. Reconciliation was more frequent when one of the combatants carried a dependent infant but rarely followed conflicts associated with food. Neither the directionality nor the decidedness of conflicts affected conciliatory tendency. In contrast, opponents that were close kin or of similar rank reconciled more often. Olive baboons did not affiliate with non‐combatants more frequently following aggression than in control periods, although affiliation with supporters and the close kin of opponents increased. Absence of consolation follows the observed cercopithecine pattern, consistent with the hypothesis that consolation requires an ability to empathize with the victim's distress. Initiation of post‐conflict attacks on third parties was not elevated in victims of aggression. The rarity of redirection is attributed to spatial dispersion, the frequent bidirectionality of baboon aggression and regular male intervention in female conflicts, all of which appear to limit the availability of ‘safe’ targets.