DOI 10.1007/s11055-015-0091-y Neuroscience and Behavioral Physiology, Vol. 45, No. 4, May, 2015
Redirection of Aggression and Consolation in Hamadryas Baboons M. L. Butovskaya,1 N. V. Meishvili,2 and V. G. Chalyan2
Translated from Rossiiskii Fiziologicheskii Zhurnal imeni I. M. Sechenova, Vol. 99, No. 6, pp. 697–705, June, 2013. Original article submitted July 23, 2012. Revised version received May 22, 2013. The outcomes of postconflict interactions between victims of aggression and third members of the group not involved in the conflict were studied in hamadryas baboons (Papio hamadryas) in a reserve. Studies were performed at the Adler Primatology Center of the Research Institute of Medical Primatology in 1996–7. We present here results obtained from analysis of redirected aggression, affiliative behavior of victims with third individuals, and consolation – the joining of third parties with the victim. A total of 445 pairs were studied, these consisting of different social categories of animals (pairs: male and female from the same harem, females from the same harem, relatives, females from different harems, males, female and almost adult male). The attracted pairs method and the time-rule method were used. Redirection of aggression was found mostly to be practiced only by males acting as victims of aggression. Both male victims and female victims typically initiated affiliative interactions with third individuals immediately after conflicts. Consolation was practiced by hamadryas baboons, but only in pairs of males and females from the same harem. Consoling males used specific forms of affiliative behavior. This is the first description of affiliation in baboons. Keywords: hamadryas baboons, postconflict behavior, redirected aggression, reconciliation, consolation, affiliation.
Intragroup conflicts threaten the social stability of groups, and it is no surprise that conflicts usually involve not only the antagonists themselves, but also other members of the group [35]. This can involve different types of intervention: support for the aggressor or victim, aggression redirected to a third individual, attempts by the conflict participants to obtain support from third parties, and postconflict affiliative interactions of third parties with the conflict participants, which is known as “consolation” [7, 20, 37]. Redirected aggression is not a universal phenomenon of all social groups in primates, but is more typical of those species characterized by despotic hierarchical relationships and a predominance of direct aggression, such as the Javanese macaque (Macaca fascicularis), the Japanese
macaque (Macaca fuscata), and the southern pig-tailed macaque (Macaca nemestrina) [5, 7, 24]. At the same time, in species with strongly marked egalitarian relationships and high probabilities of returned aggression, redirected aggression is seen more rarely (the olive baboon, Papio anubis) [12]. It has also been suggested that in species with strongly marked sexual dimorphism (mountain gorillas, Gorilla gorilla beringei, olive baboons), the transfer of aggression to a third individual does not occur because of the excessively high cost of this behavior [12, 38]. In addition, it has also been suggested that the probability that aggression will be redirected depends on the nature of the food strategy employed by the primates being studied [12]. Redirection of aggression is less likely in species covering wide areas for foraging olive baboons, mountain gorillas). At the same time, in Javanese macaques, in which all individuals of one group can feed simultaneously in a single tree, redirected aggression is encountered extremely frequently. Hamadryas baboons are an optimum species for testing the correctness of these hypotheses, as, like olive baboons, they have strong-
1 Institute
of Ethnology and Anthropology, Russian Academy of Sciences, Moscow, Russia; e-mail:
[email protected]. 2 Research Institute of Medical Primatology, Russian Academy of Medical Sciences, Veseloe-1, Sochi-A, Russia.
417 0097-0549/15/4504-0417 ©2015 Springer Science+Business Media New York
418 ly marked sexual dimorphism and high levels of returned aggression. At the same time, like Javanese macaques, individuals of one hamadryas baboon harem unit remaining in the spatial vicinity of each other throughout the day [16, 26]. Because the unfavorable consequences of aggression threaten the wellbeing of the whole group, members of the group other than the aggressor and the victim may become involved in postconflict interactions facilitating restoration of peace and the relationships interrupted by the conflict. In particular, a whole series of species show increases in postconflict interactions between the former aggressor and related victims: Javanese macaques, Japanese macaques, Barbary macaques (Macaca nigra), and Guinea baboons (Papio papio) [5, 7, 29, 30]. No increases in affiliative contacts between the victim and the relatives of the aggressor in these species are seen. Most macaque species also show no signs of affiliation between victims and their own relatives, similar to the situation described in Guinea baboons [5, 7, 30]. It seems that the probability of postconflict affiliation on the initiative of the antagonists with other members of the group differs in members of different adult classes. Animals usually prefer to join with those members of the group with which they form strong bonds. Thus, female gorillas in the role of victims of aggression generally initiate affiliation with their male leader [38]. At the same time, the occurrence of this behavioral pattern may be associated with the level of suffering of the victim and its frustration [13]. In contrast to reconciliation, consolation is a rare phenomenon [37]. Until the present time, virtually the only description of consolation has been in anthropoid monkeys (Pan troglodytes, P. paniscus, Gorilla gorilla beringei), though it has also been noted in the brown capuchin (Cebus apella) and brown macaques (Macaca arctoides) [11, 18, 22, 27, 28, 31, 35, 38]. Consolation has not been observed in marmosets, other macaques, or baboons [14, 20, 27]. Given that consolation is mainly a feature of anthropoid monkeys, it has been suggested that its appearance requires more developed intellectual capacities than those in the possession of the lower monkeys (the social intellect hypothesis) [36]. Nonetheless, data on capuchins and brown macaques show that some lower monkeys can perform a type of consolation [11, 34]. In the light of this fact, other explanations for the absence of consolation in monkeys become possible, particularly the “social constraint” hypothesis [36]. There may be interspecies differences in the extent of social constraint from third individuals. Given that hamadryas baboons have a complex social and spatial structure [2, 15, 17, 26], they are the most suitable species for testing the main hypotheses of the functions of consolation in primate society, as well as for verifying concepts of the need for certain mental capacities to be present for it to occur. The aim of the present work was to study the presence of the following postconflict social manifestations: redirection of victims’ aggression onto other members of the group, victim-induced affiliation with other members of the group,
Butovskaya, Meishvili, and Chalyan and affiliation with victims initiated by other members of the group (consolation). Methods Studies were performed in September–November 1996 and 1997 at the Russian Primatology Center (Research Institute of Medical Primatology, Russian Academy of Medical Sciences) in Adler [1]. The study group of hamadryas baboons consisted of 60–66 individuals and was kept in an enclosure of 600 m2. Redirection of aggression by victims was analyzed, along with the initiation of affiliation by victims with other members of the group and initiation of affiliation of other members of the group with victims (the study group and the methods used have been described in more detail in our previous report on studies of reconciliation in hamadryas baboons [1]). The following categories of pairs were identified: male and female of the same harem, female and male of the same harem, female and female of the same harem, and relative and relative (mother and daughter, maternal siblings). All cases of redirected aggression, initiation of affiliation with the victim, and initiation of affiliation by the victim of union with third individuals were tested by comparing postconflict and control observations (PC-MC method) [1]. The present study used two methods: the attracted pairs method [1] and the “time rule” method [4]. All aggressive interactions initiated by the victim during the postconflict period (PC) in relation to third individuals not taking part in the conflict were regarded as redirected aggression. The control for these consisted of aggressive interactions initiated in the control period (MC) by the victim in relation to third individuals. Affiliation of victims with third individuals and affiliation of third individuals with victims refer to the following contact patterns of behaviors: grooming, sitting close together, necking, examining the genitals, covering each other, lying on, making close body contact, and holding hands [17, 26]. Overall, results from comparisons of postconflict and control observations of a total of 445 pairs were analyzed. Analysis was performed using nonparametric methods. Trends in affiliative postconflict interactions were identified using the following measures: 1) an absolute measure of affiliative tendencies determined by dividing the difference between the numbers of attracted and dispersed pairs by the total number of pairs (identified in the text as V) [33]; 2) a relative measure of the affiliative tendency obtained by dividing the difference between attracted and dispersed pairs by the sum of the attracted and dispersed pairs (identified in the text as R) [10, 25]; 3) a measure of total affiliation, obtained by dividing the sum of attracted and dispersed pairs by the sum of attracted, dispersed, and neutral pairs (identified in the text as T) [10, 25]. The number of interactions between individuals was evaluated on the basis of grooming frequency in each pair of individuals and their spatial vicinity, i.e., the mean distance between individuals [1]. Results Redirected aggression. For the whole group overall, victims demonstrated redirected aggression in 42 cases of
Redirection of Aggression and Consolation in Hamadryas Baboons
419
TABLE 1. Consolation in Different Social Categories of Hamadryas Baboons Pairs
a
d
n
V, %
R, %
T, %
Male/female of same harem
69
29
62
25
40.8
61.3
Relative/relative
25
15
17
17.5
25.0
70.2
Unrelated female/female of same harem
27
19
164
3.8
17.4
21.9
Female/male of same harem
18
20
21
–3.4
–5.3
64.0
445 postconflict observations, compared with 15 cases of 445 control observations during the control period. The difference between the numbers of attracted and dispersed pairs was significant (χ2 = 11.86, p < 0.001) (Wilcoxon, z = 2.38, n = 25, p < 0.017). Redirection of aggression was most likely during the first 30 sec of the postconflict period. Of 225 PC-MC pairs in which the victims of aggression were female, redirection of aggression by victims was noted earlier in the postconflict period in 21 cases, compared with 10 in the control period (binomial test, p > 0.05). Of 59 PC-MC pairs in which the aggressor and victim were male, 20 pairs were attracted and two were dispersed. The difference between the numbers of attracted and dispersed pairs was significant (binomial test, p < 0.01) (Wilcoxon, T+ = 21, n = 6, p < 0.03). In 45% of cases, male victims of conflicts with other males redirected their aggression to females or adolescents of the same harem, while in 20% of cases, the target of redirected aggression of males was a male of the same group and in 35% of cases, males redirected their aggression to males of the neighboring troop of baboons. Initiation of affiliative contacts with a third individual. In terms of this measure, of 445 PC-MC pairs in the whole group, a total of 260 pairs were attracted and 90 were dispersed, the remainder being neutral. There was a significant difference between attracted and dispersed pairs (χ2 = 81.6, p < 0.0001). The trend to affiliative unification with a third individual was maximal during the first 30 sec after completion of the conflict (Kolmogorov–Smirnov, m = 312, n = 204, D = 0.371, p < 0.001). Analysis of postconflict affiliation of victims of conflicts in which the losers were female showed that of 306 female conflict victim/third individual pairs, 201 were attracted and 60 were dispersed (χ2 = 75.1, p < 0.0001) (Wilcoxon, T+ = 457, n = 27, p < < 0.001). Of 59 cases in which the victims of aggression were male, 31 male victims joined with third individuals earlier in the postconflict period and 14 during the control period (binomial test, p < 0.05) (Wilcoxon, T+ = 36, n = 8, p < 0.02). Consolation. Analysis of data for the whole group showed that there were no significant differences between the numbers of attracted and dispersed pairs for dyads of third individuals with victims (a = 159, d = 143, p > 0.05). Considering our previous observation that pair composition influences the probability of postconflict resolution [1], we
analyzed postconflict affiliation in the following categories of pairs: female of the same harem/female victim, female of the same harem/male victim, relative/relative victim, and male of the same harem/female victim (see Table 1). This analysis showed that of 210 cases in which females were the victims of conflicts, in 27 the third individual – an unrelated female of the same harem – approached the victim and demonstrated affiliative unification during the postconflict period earlier than during the control period. Conversely, in the control period this behavior of third individuals who were unrelated females of the same harem was seen earlier in 19 cases. Although the difference between the numbers of attracted and dispersed pairs was not significant, there was a trend to consolation of females victims of aggression by third individuals who were females from the same harem. Measures of consolation were as follows: absolute consolation V = 3.8%, relative consolation R = 17.4%, and total affiliation T = 21.9%. For those cases in which males were the victims of aggression by other males, the probability of affiliation of these animals with females of their own harem was low. Of 59 such pairs, 18 pairs were attracted and 20 were dispersed, the difference between attracted and dispersed pairs being insignificant: V = –3.4%, R = –5.3%, and T = 64%. Females evidently preferred to avoid their male leaders immediately after their conflicts with other males. Of 57 postconflict and control relative/relative victim pairs, there were 25 attracted pairs and 15 dispersed pairs. Although the difference in this case was not significant, there was some tendency to consolation of relatives after conflicts: V = 17.5%, R = 25%, and T = 70.2%. A total of 160 examples of the “male third individual/female victim” pair category were studied. A significant difference was found between the numbers of attracted and dispersed pairs (a = 69, d = 29, χ2 = 15.52, p < 0.001). In addition, a higher probability of affiliation was found between consoling males and female victims throughout the period from 15 sec to 1 min 15 sec after the end of the conflict (Kolmogorov–Smirnov, D = 0.45, p < 0.01). Absolute consolation V was higher in this than in all other categories of pairs, at 25%; relative consolation R was also higher than in other categories of pairs, at 40.8%; T was 61.3%. At the next stage, we performed an independent analysis of the tendencies of males to console females in rela-
420 tion to the identity of the aggressor – a female of the same harem or a female of another harem. A total of 85 “male third individual/female victim of conflict with a female of another harem” pairs were studied. This yielded results providing evidence of a high probability of consolation by the male of the female who had fought with a female of another harem (a = 52, d = 16, χ2 = 18.01, p < 0.001; V = 42.4%, R = 52.9%; T = 80%). Conversely, if the female was a victim of the aggression of a female of the same harem, the probability of consolation by the male of the victim of such a conflict decreased sharply. Of 75 such pairs, 17 were attracted and 13 were dispersed, the difference not being significant; V = 5.3%, R = 13.3%, and T = 40%. Analysis of the behavioral patterns noted on consolation by males of females of the same harem showed that there were significant differences in the structure of the behavioral repertoire of males in the postconflict and control periods (χ2 = 65.62, df = 12, p < 0.001). Behaviors of the “male holds female’s bottom “ type (χ2 = 11.79, df = 1, p < 0.001) and the “male lies on female” type (χ2 = 14.5, df = 1, p < 0.001) were seen significantly more frequently in the postconflict period. At the same time, grooming was seen more frequently in the control period (χ2 = 13.77, df = 1, p < 0.001). Discussion Redirected aggression, dominance and “good relationships.” Hamadryas baboon aggression victims are inclined to redirect their aggression to third individuals. In this regard, they are more similar to phylogenetically distant macaque species (Macaca fascicularis, Macaca fuscata) than to the baboon-like Anubis [3, 7, 12], which can be explained using a socioecological approach. For hamadryas baboons constituting a single harem and constantly in each other’s close vicinity, like Javanese macaques feeding in the same tree, it is significantly easier to find an object to which to redirect aggression than it is for Anubis baboons, which are widely disseminated. Redirection of aggression was found to be practiced mainly by male victims, which usually redirected their aggression to females of the same harem or adolescents, i.e., to individuals with whom they had good relationships and with whom they could subsequently make up quarrels. The reason why males had a low probability of redirecting their aggression to other males is that this type of redirecting is in essence an escalation of the conflict, which could lead to high costs to the male. Female hamadryas baboons do not redirect the aggression they have received, and in this regard are no different from female gorillas [38]. Differences in the probability of demonstrating redirected aggression between male and female hamadryas baboons may also be due to differences in the times at which males and females show the tendency to reconciliation. As we have demonstrated previously [1], female hamadryas baboons are inclined to reconciliation within the first minute after the end of the conflict, while males generally do this during the fourth minute after completion of conflict. Rapid reconciliation gives females the
Butovskaya, Meishvili, and Chalyan greatest chance of relieving the conflict-induced stress and tension and eliminating the need to prolong the conflict. Unlike females, males could redirect their aggression during the four minutes after conflict or could calm down by means of affiliating with a third individual, or, least likely, could make peace with the antagonist. Postconflict affiliation of victims with third individuals. After completion of conflicts, hamadryas baboon victims (both males and females) made attempts to affiliate with third individuals. In this regard, they were more similar to chimpanzees, gorillas, and brown capuchins than macaques and Anubis baboons [5, 12, 34, 36]. In contrast to macaques and Anubis baboons, in which affiliation of victims with their relatives was observed, female hamadryas baboon victims preferred to take part in affiliative interactions with their male leader. Male victims of aggression behaved similarly, joining females of their own harem after conflicts. The cause of the differences in the nature of postconflict affiliations in these two baboon species appears to be the differences in social structure in hamadryas and Anubis baboons [15, 19, 26, 32] and differences in the style of dominant relationships – despotic in hamadryas baboons and egalitarian in Anubis baboons. Can consolation occur in old world monkeys? Twenty-some years ago, specialists in the cognitive abilities of animals suggested that reconciliation is a property only of anthropoid primates, as only these species have the level of cognitive abilities required to support the animal’s own safety, empathy, and affection [23]. More recent studies have demonstrated reconciliation in many primate species, including lemurs. Most primatologists agree with the suggestion of de Waal and Yoshihara [36], that memory, selfawareness, and the inclination to form friendly contacts after conflicts create all the conditions required for reconciliation. More evidence will accumulate with time to support the consolation phenomenon in the lower monkeys. Consolation has now been described in brown capuchins, as well as brown macaques. The results of this study, considered along with the results of some previous investigations [9, 39], show that consolation also occurs in hamadryas baboons, though it is practiced almost exclusively by adult males in relation to their females. This type of behavior in males is virtually the only means by which they can release the high level of stress in females (the level of stress experienced by females can be assessed in terms of their screeches and high frequency of micturition and defecation) in situations in which reconciliation of the victim with the aggressor is unlikely. Consolation in hamadryas baboons is reminiscent of analogous behavior in mountain gorillas in nature. Male mountain gorillas console and calm their females after conflicts in response to their active pleas [38]. As in gorillas, but in contrast to baboons, requesting consolation is practiced in hamadryas baboons, mainly in female-male pairs [34, 38]. In addition, some positive tendency to consolation
Redirection of Aggression and Consolation in Hamadryas Baboons was also seen in pairs of relatives. Females usually avoid tight relationships with their male immediately after they have been victim of the aggression of another male. This is not surprising, as the probability that aggression will be redirected by male hamadryas baboons is very high. Like gorillas, hamadryas baboons do not show any signs of consolation in pairs of unrelated females belonging to the same harem [38]. Male hamadryas baboon behavior directed to consoling females is generally associated with demonstration of a threat towards the protagonist, which is evidence that the male is ready to defend the female. This species shows significant social constraint. Therefore, in contrast to Anubis baboons, the risk to the consoling male of becoming the target of redirected aggression as a result of taking this action is no higher than if the animal preferred to avoid the female victim of aggression. Thus, selective consolation can be regarded as part of the advantage obtained by females from stable interactions with males [36]. Consolation may be an important component of the behavioral strategy of males, as they can use it to achieve consistent success with females. In addition, it can be an effective means of reducing tension between different harems. Males less able to demonstrate consolation may also be less successful in retaining females as constant partners. Conversely, consolation of females by males after their conflicts with females of their own harem is less favorable for males, as in this case the intervention of males promotes increased arguments between females and decreases harem stability. The uselessness of intervention by males in these cases is also determined by the fact that there is a quite high probability of reconciliation of females from the same harem. The female consolation strategy in hamadryas baboons may have evolved in parallel with the evolution of grazing behavior, “herding behavior” using specific patters of consolation behavior (the male holds the female with both hands – bottom-holding – and the males lies on the female – lying on). It should be noted that the example of hamadryas baboons is a good illustration of the application of the social constraint hypothesis [36]. Although we observed behavior in hamadryas baboons which appeared externally to be consolation, we cannot confidently assess the cognitive aspect of this phenomenon. At the same time, we must not forget that baboons have more cortex than other old world monkeys [21], which provides some grounds for suggesting that they have empathy. The existence of consolation behavior in hamadryas baboons may be associated with the complex social structure and highly differentiated social relationships. However, this does not mean that the “theory of mind” cannot be used to explain the phenomenon of consolation in different species. Conclusions Redirected aggression is practiced by hamadryas baboons. This behavior is seen mainly in male victims of
421
aggression. Victims attack individuals of significantly lower social status, allowing easy restoration of relationships in the future. Both male victims and female victims are characterized by requesting support from third individuals immediately after conflicts end. Consolation is practiced by hamadryas baboons, but is characteristic almost only of “male/female of the same harem” pairs. This is the first description of consolation in baboons. Consolation in hamadryas baboons is apparent as specific patterns of behavior. This study was supported by the Russian Foundation for Basic Research (Grant Nos. 96-06-80405 and 99-06-80346). We would like to thank A. Kozintsev, O. Petit, and B. Thierry for discussions, comments, and advice. REFERENCES 1.
2.
3. 4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
M. L. Butovskaya, V. G. Chalyan, and N. V. Meishvili, “Reconciliation in hamadryas baboons (Papio hamadryas): testing the relationships quality hypothesis,” Ros. Fiziol. Zh., 97, No. 8, 870–876 (2011). V. G. Chalyan, N. V. Meishvili, and M. L. Butovskaya, “The role of females in hamadryas baboon (Papio hamadryas) societies. 1. Female dominance hierarchy in the herd at the Gumistinskii wildlife sanctuary,” Vestn. Antropol., 3, 126–145 (1997). F. Aureli, “Post-conflict behavior among wile long-tailed macaques (Macaca fascicularis),” Behav. Ecol. Sociobiol., 31, 329–337 (1992). F. Aureli, C. P. van Schaik, and J. A. R. A. M. van Hoof, “Functional aspects of reconciliation among captive long-tailed macaques (Macaca fascicularis),” Am. J. Primatol., 19, 39–51 (1989). F. Aureli and C. P. van Schaik, “Post-conflict behavior in long-tailed macaques (Macaca fascicularis). 1. The social events,” Ethology, 89, 89–100 (1991). F. Aureli and C. P. van Schaik, “Post-conflict behavior in long-tailed macaques (Macaca fascicularis). II. Coping with uncertainty,” Ethology, 89, 101–114 (1991). F. Aureli, H. C. Veenema, et al., “Reconciliation, consolation, and redirection in Japanese macaques (Macaca fuscata),” Behaviour, 124, 1–21 (1993). R. A. Barton, “Sociospatial mechanisms of feeding competition in female olive baboons, Papio anubis,” Anim. Behav., 46, 791–802 (1993). M. L. Butovskaya, A. G. Kozintsev, N. V. Meishvili, and V. G. Chalian, “Reconciliation in hamadryas baboons,” in: Abstr. 17th Int. Congr. of the Primatological Society, Antananarivo, August 10–14 (1998), p. 132. M. L. Butovskaya and A. G. Kozintsev, “Aggression, friendship, and reconciliation in Russian primary school children,” Aggress. Behav., 25, 125–139 (1999). J. Call, F. Aureli, and F. B. M. de Waal, “Post-conflict third-party affiliation in stumptailed macaques,” Anim. Behav., 63, No. 2, 209–216 (2002). D. L. Castles and A. Whiten, “Post-conflict behavior of wild olive baboons. I. Reconciliation, redirection and consolation,” Ethology, 104, 126–147 (1998). D. L. Castles and A. Whiten, “Post-conflict behavior of wild olive baboons. II. Stress and self-directed behavior,” Ethology, 104, 148–160 (1998). D. L. Cheney and R. M. Seyfarth, “Redirected aggression and reconciliation among vervet monkeys, Cercopithecus aethiops,” Behaviour, 110, 258–275 (1989).
422 15.
16.
17.
18.
19.
20.
21. 22.
23. 24. 25. 26. 27.
Butovskaya, Meishvili, and Chalyan F. Colmenares, “Clans and harems in a colony of hamadryas and hybrid baboons: male kinship, familiarity and the formation of brother-teams,” Behaviour, 120, 61–94 (1992). F. Colmenares, M. G. Lozano, and P. Torres, “Harem social structure in a multiharem colony of baboons (Papio sp.): A test of the hypothesis of the ‘star-shaped’ sociogram,” in: Current Primatology. II. Social Development, Learning and Behaviour, J. J. Roeder et al. (eds.), Univ. Louis Pasteur, Strasbourg (1994), pp. 93–101. F. Colmenares and C. Lozaro-Perea, “Greeting and grooming during social conflicts in baboons: Strategic uses and social functions,” ibid., pp. 165–174. G. Cordoni, E. Palagi, and S. Borgognini Tarli, “Reconciliation and consolation in captive western gorillas,” Int. J. Primatol., 27, No. 5, 1365–1382 (2006). G. Cowlishaw, “Behavioural patterns in baboon group encounters: The role of recourse competition and male reproductive strategies,” Behaviour, 131, 75–86 (1995). M. Das, Z. Penke, and J. A. R. A. M. van Hoof, “Affiliation between aggressors and third parties following conflicts in long-tailed macaques,” Int. J. Primatol., 18, 159–181 (1997). R. I. M. Dunbar, “Neocortex size as a constraint on group size in primates,” J. Human Evol., 22, 469–493 (1992). O. N. Fraser, D. Stahl, and F. Aureli, “Stress reduction through consolation in chimpanzees,” Proc. Natl. Acad. Sci. USA, 105, No. 25, 8557–8562 (2008). G. Gallup, “Self-awareness and the emergence of mind in primates,” Am. J. Primatol., 2, 237–248 (1982). P. G. Judge, “Dyadic and triadic reconciliation in pigtail macaques (Macaca nemestrina),” Am. J. Primatol., 23, 225–237 (1991). A. G. Kozintsev, “On measuring reconciliation and friendship,” Adv. Ethol., 32, 155 (1997). H. Kummer, Primate Societies, Aldine, Chicago (1971). N. Kutsukake and D. Castles, “Reconciliation and post-conflict third-party affiliation among wild chimpanzees in the Mahale Mountains, Tanzania,” Primates, 45, No. 3, 157–165 (2004).
28.
29. 30.
31.
32.
33. 34.
35.
36.
37. 38.
39.
E. Palagi, T. Paoli, and S. Borgognini Tarli, “Reconciliation and consolation in captive bonobos (Pan paniscus),” Am. J. Primatol., 62, No. 1, 15–30 (2004). O. Petit and B. Thierry, “Reconciliation in a group of black macaques (Macaca nigra),” J. Wild. Preserv. Trusts, 30, 89–95 (1994). O. Petit and B. Thierry, “Reconciliation in a group of Guinea baboons (Papio papio), in: Current Primatology. II. Social Development, Learning and Behaviour, J. J. Roeder et al. (eds.), Univ. Louis Pasteur, Strasbourg (1994). T. Romero, M. Castellanos, and F. B. M. de Waal, “Consolation as possible expression of sympathetic concern among chimpanzees,” Proc. Natl. Acad. Sci. USA, 107, No. 27, 12,110–12,115 (2010). R. M. Sayfarth, “Social relationships among adult male and female baboons. II. Behaviour throughout the female reproductive cycle,” Behaviour, 64, 227–247 (1978). H. C. Veenema, M. Das, and F. Aureli, “Methodological improvements for the study of reconciliation,” Behav. Process., 31, 29–37 (1994). P. Verbeeck and F. B. M. de Waal, “Postconflict behavior of captive brown capuchins in the presence and absence of attractive food,” Int. J. Primatol., 18, 703–725 (1997). F. B. M. de Waal, “Reconciliation among primates: a review of empirical evidence and unresolved issues,” in: Primate Social Conflict, W. A. Mason and S. P. Mendoza (eds.), N. Y. State Univ. Press, Albany (1993). F. B. M. De Waal and F. Aureli, “Consolation, reconciliation and possible cognitive difference between macaques and chimpanzees,” in: Reaching into Thought: The Minds of the Great Apes, A. E. Russon et al. (eds.), Cambridge Univ. Press, Cambridge (1996). F. B. M. de Waal and A. van Roosmalen, “Reconciliation and consolation among chimpanzees,” Behav. Ecol. Sociobiol., 5, 55–66 (1979). D. P. Watts, “Post-conflict social event in wild mountain gorillas. II. Redirection, side direction and consolation,” Ethology, 100, 158–174 (1995). F. Zaragoza and F. Colmenares, “Reconciliation and consolation in hamadryas baboons, Papio hamadryas,” Adv. Ethol., 32, 158 (1997).
