Primates (2004) 45:157–165 DOI 10.1007/s10329-004-0082-z

O R I GI N A L A R T IC L E

Nobuyuki Kutsukake Æ Duncan L. Castles

Reconciliation and post-conflict third-party affiliation among wild chimpanzees in the Mahale Mountains, Tanzania

Received: 10 September 2002 / Accepted: 12 February 2004 / Published online: 28 April 2004 Ó Japan Monkey Centre and Springer-Verlag 2004

Abstract This study investigated post-conflict (PC) behavior among wild chimpanzees (Pan troglodytes) of the M-group in the Mahale Mountains, Tanzania, and examined what types of behavior characterize the PC situation in this group, and the factors that influence the occurrence of PC affiliation between opponents soon after the end of an aggressive conflict (i.e., reconciliation). We found that the opponents affiliated selectively soon after the end of aggression, suggesting that reconciliation occurred in this group. The mean individual corrected conciliatory tendency (CCT) (Veenema et al. 1994 in Behav Proc 31:29–38) was 14.4%, which is similar to or lower than frequencies observed in studies of captive and wild chimpanzees. The valuable relationship hypothesis predicts that the CCT is higher among individuals who share valuable relationships (e.g., males or affiliative dyads) than among individuals who do not (e.g., females or less-associative dyads). However, the analysis based on data for aggression between unrelated individuals (including one incident between an adult and non-adult) and aggression between unrelated adults, did not uncover this difference. Affiliation by a previously uninvolved individual with the victim (‘‘consolation’’) and with the aggressor (‘‘appeasement’’) occurred more frequently following aggression than in the control condition. The results are compared with previous studies of captive and wild chimpanzees.

N. Kutsukake (&) Æ D. L. Castles Department of Cognitive and Behavioral Science, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan E-mail: [email protected]; [email protected] N. Kutsukake Department of Biological Sciences, Graduate School of Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan Present address: N. Kutsukake Large Animal Research Group, Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, UK

Keywords Chimpanzees Æ Reconciliation Æ Consolation Æ Post-conflict behavior Æ Intra-specific variation

Introduction Since the first systematic study of post-conflict (PC) behavior in a captive colony of chimpanzees (de Waal and van Roosmalen 1979), conflict management and resolution strategies have received much attention (Aureli and de Waal 2000; de Waal 2000; Aureli et al. 2002). Reconciliation (PC affiliation between former opponents soon after the conclusion of a conflict) functions to reduce the probability that the victim of aggression will suffer further attack by either the initial aggressor or other group members, to reduce the PC stress of opponents (Katsukake and Castles 2001), and to restore tolerance around food sources (reviewed in Aureli et al. 2002, and see references therein). Since reconciliation does not always occur after aggression, various studies have investigated the conditions under which opponents reconcile rather than allow PC hostility to persist. One factor that may well facilitate the occurrence of reconciliation is the quality of the opponents’ relationship. The ‘‘valuable relationship hypothesis’’ predicts that reconciliation is more frequent following aggression between opponents whose relationship is of a high biological value; this is understood as a function of the fitness benefits that can be derived from the relationship (de Waal and Yoshihara 1983; Aureli et al. 2002). Wild chimpanzees live in multimale–multifemale groups with male philopatry and female dispersal (Goodall 1986). In this species, PC behavior has been reported in four captive groups [Arnhem colony: de Waal and van Roosmalen 1979, de Waal 1986; Detroit Zoo: Baker and Smuts 1994; Yerkes field station: de Waal and Aureli 1996; Preuschoft et al. 2002; Chimpanzee and Human Communication Institute

158

(CHCI): Fuentes et al. 2002] and two wild groups (the Sonso group in Budongo Forest, Uganda: Arnold and Whiten 2001; North community in Tai National Park, Cote d’Ivoire, Wittig, personal communication: Wittig and Boesch 2003; see also Goodall 1986; Muller 2002). In chimpanzees, males are social, and they cooperatively attack neighboring groups; females, by contrast, are less social (Goodall 1986). Thus, on the basis of the valuable relationship hypothesis it has been predicted that males should reconcile more frequently than females. Indeed, Arnold and Whiten (2001) found that aggression between females was never reconciled. Furthermore, affiliation level has been found to predict the occurrence of reconciliation, with affiliative dyads reconciling more frequently than less-affiliative dyads (Preuschoft et al. 2002; Wittig and Boesch 2003). However, several studies in captive conditions have shown a similar or higher conciliatory tendency between females than males (e.g., Baker and Smuts 1994; Preuschoft et al. 2002). This difference might have been due to differences in living condition (wild vs captive) or demographic conditions (the small number of individuals in captivity), but the exact reason is unknown due to the lack of comparable data for chimpanzees in the wild. Although reconciliation may be the best option for reducing the cost of aggression, it has been argued that other types of PC behavior involving a third party (PC third-party affiliation or ‘‘triadic’’ PC interaction) have a similar function (reviewed in Cords 1997; Das 2000; Watts et al. 2000). For example, PC affiliation with a victim of aggression initiated by an uninvolved third individual, so called ‘‘consolation,’’ has been confirmed in captive chimpanzees (de Waal and van Roosmalen 1979; de Waal and Aureli 1996) and in stump-tailed macaques (Macaca arctoides) after classifying the specific behaviors used in PC affiliation (Call et al. 2002). PC affiliation with an aggressor initiated by a third individual, hereafter called ‘‘appeasement,’’ has been confirmed in several species of macaques (Das 2000). These types of PC third-party affiliation seemingly function to alleviate the PC stress of the opponents, although functional aspects of these types of PC thirdparty affiliation have not been tested empirically, and it is likely that the function differs according to the social category of the affiliating third party (e.g., own kin, kin of the opponents, and non-kin; Das 2000; Watts et al. 2000). Previously, only one study (Yerkes) observed quantifiable evidence of consolation following aggression (de Waal and Aureli 1996); conversely, Arnold and Whiten (2001) reported its absence in a wild group, suggesting that consolation is not in the PC behavioral repertoire of wild chimpanzees. Since chimpanzees show wide intra-specific variation in social behavior (Boesch et al. 2002), it is important to compare data from various study sites. In this study, we report PC behavior among wild chimpanzees in the Mahale Mountains National Park, Tanzania, to provide data for comparison with previous studies. In particular, we investigated what types of PC affiliation

characteristically follow aggression, and tested the valuable relationship hypothesis by investigating the factors that influence the occurrence of reconciliation.

Methods Study group and group composition This study was conducted in the Mahale Mountains National Park, which is located on the eastern shore of Lake Tanganyika, in western Tanzania. A long-term study of wild chimpanzees has been underway in Mahale since 1965 (Nishida 1990). All observations were made by N.K., between September and December 2000 and between February and September 2001 (Kutsukake and Matsusaka 2002; Kutsukake 2003). At that time, the study group (M-group) consisted of 51– 54 individuals, including 8 adult males (>15 years old) and 20 adult females. In addition, 1 adolescent male (PM) was included in the adult class because he had reached adult body size and received pant–grunts from adult females. Of these, we selected all nine adult males and nine adult females as observation targets, and observed them using focal animal sampling (Table 1; Kutsukake 2003). On each observation day, we chose one focal individual to follow for as long as possible; the choice of focal individual was based on the criterion that data be evenly accumulated for every individual. We did not observe the same individual on 2 successive days. In total, we observed each focal individual for more than 50 h, and the total observation time was about 1,100 h. Many aggressive interactions involving a focal animal were recorded during the focal observations. Since the focal observations were continuous, the behavior of the focal animal following aggression can be considered PC data (de Waal and Yoshihara 1983; Matsumura 1996). A preliminary investigation showed that most PC affiliation and aggression occurred within 10 min of aggression, and that the results for 10 and 20 min did not differ. Arnold and Whiten (2001) analyzed the 30min PC period, but also showed that most PC interactions occurred within 10 min (see Figs. 1, 9, 10 in their study). In this study, we focused on the immediate (10min) PC period. When we were able to observe the focal animal’s behavior throughout the aggressive interaction and the PC behavior, we analyzed the nature of the aggression. Chasing, physical assault, agonistic display, and biting were all defined as aggression. Following Preuschoft et al. (2002) and Fuentes et al. (2002), we reset the PC period to start immediately after a further bout of aggression was concluded, if aggression reoccurred between opponents within 2 min. To analyze the occurrence of reconciliation, a matched control (MC) observation of the same duration as the PC data was chosen, a posteriori, from the focal animal sampling data. In the wild, unlike in captive studies, it is almost impossible to conduct systematic

159 Table 1 Identities of focal individuals, the number of PC–MC data, and corrected conciliatory tendency(CCT) of reconciliation ID

Birth

Dominance ranka

No. of focal days

PC–MC data (no. of dyads)

Attracted

Dispersed

Neutral

Individual CCT

Male DE MA FN HB DG BB AL CT PM

1963? 1977 1978? 1980? 1981? 1981 1985 1985? 1988

4 5 1 7 2 8 3 6 9

9 10 9 9 8 12 11 10 9

13 5 18 7 13 12 1 12 23

4 0 5 1 3 1 0 3 4

1 1 1 0 0 1 0 1 0

8 4 12 6 10 10 1 8 19

23.1 )20 22.2 14.3 23.1 0 ) 16.7 17.4

(12) (4) (11) (4) (10) (10) (1) (7) (11)

ID

Birth

Offspringb

No. of focal days

PC-MC data (no. of dyads)

Attracted

Dispersed

Neutral

CCT

Female FT OP PI JN XT MJ AK CY AB

1963? 1971? 1972? 1974? 1975? 1980? 1981? 1982? 1982

88M (PM), 99F 86F, 91M, 98M 91M, 00F 95F, 00F 95M, 00F 96M, 01F 98F 98M 98F

8 7 9 8 8 8 8 10 8

9 14 3 10 19 8 9 12 18

0 5 0 3 4 4 2 3 0

0 2 0 1 1 0 0 0 1

9 7 3 6 14 4 7 9 17

0 21.4 0 20 15.8 50 22.2 25 –5.6

a

(8) (8) (2) (5) (12) (6) (8) (8) (7)

Dominance rank was determined by the direction of pant–grunt (Kutsukake 2003) 88M indicates that there was a male offspring born in 1988 within the group during the study period

b

baseline observations because of the fission–fusion social system and because of the difficulty in finding the observation target, when following a predetermined schedule. Therefore, we loosened the criteria for MCs and in choosing MCs we prioritized to match the following conditions: 1. An MC was chosen as the closest focal observation in time, in which the activity of the focal individual matched that at the time that the aggression occurred. 2. The data before which the focal individual was not involved in aggressive interaction, for at least 10 min were selected as the MC. 3. To control for the distance between opponents and between a focal individual and a third party, the MC started when the opponents moved to within 10 m of each other. In all, there were 206 PC–MC pairs (Table 1; mean of PC–MC pairs =11.4; the data for AL was excluded from some of the analyses, as AL contributed only one PC–MC). Out of 206 PC–MC pairs, the focal individual was the aggressor in 100 interactions and the victim in 106. In the PC and MC data, affiliative and aggressive interactions towards group members were recorded, and this study analyzed the first affiliative interactions. Interactions with individuals less than 4 years of age were ignored. Affiliative interactions included allogrooming, playing, sitting in contact, gentle touching, kissing, embracing, wrapping an arm around another, inspecting another’s genitals, passing touch, mounting, and grasping the testicles (Arnold and Whiten 2001).

Dyadic association During focal observations, we recorded the neighbors (<3 m) of the focal individual every 10 min using the instantaneous sampling method (Altmann 1974) to examine the dyadic association pattern (see Kutsukake 2003, for details). For a conservative estimate of the association pattern, we deleted sampling data in which the neighbor(s) did not change (Newton-Fisher 1999). From those data, we calculated the ‘‘simple ratio index’’ in each dyad (Cairns and Schwager 1987). To categorize the association level, we calculated the quartile points of the dyad association level between unrelated individuals for each focal individual. We defined the dyads whose association score was higher than the third quartile score as ‘‘affiliative,’’ those whose association score was less than the first quartile as ‘‘non-affiliative,’’ and others as ‘‘neutral’’ (Cords and Aureli 1993). Related individuals (mother–offspring, brothers or sisters) were considered affiliative group members. Statistical analysis To investigate the occurrence of reconciliation, we used two methods of analysis. First, following the PC–MC method of de Waal and Yoshihara (1983), a PC–MC pair was labeled ‘‘attracted’’ if the opponents engaged in a social event only in the PC data, or earlier in the PC data than in the MC data. Similarly, a PC–MC pair was labeled ‘‘dispersed’’ if the opponents engaged in a social event only in the MC data, or earlier in the MC data than in the PC data. For each individual, we compared

160

the proportions of attracted and dispersed pairs by the Wilcoxon signed-ranks test. When following the ‘‘time rule’’ method (Aureli et al. 1989), for each PC and MC observation, we determined the minute in which the first social event occurred. Next, we compared the distribution of the first PC events with MC events using the Kolmogorov–Smirnov test. If this test produced a significant result, we then ran a Wilcoxon signed-ranks test comparing individual PC and MC scores within the time period in which the PC data distribution differed from those for the MC. In this way, we checked the generality of a tendency at the individual level. As an index of reconciliation frequency, we used the corrected conciliatory tendency (CCT) of Veenema et al. (1994), which is a modification of the measure that de Waal and Yoshihara (1983) used to account for baseline levels of affiliation. An individual’s CCT=(attracted pairs)dispersed pairs)/total number of PC–MC pairs. Unless otherwise noted, all statistical analyses were conducted at the individual level, for animals for which there were three or more PC–MC pairs (victim of aggression: n=14; aggressor: n=11). All analyses were two-tailed and the significance level was 5%.

Results Demonstration of reconciliation Following the PC–MC method, chimpanzees were significantly more likely to affiliate with former aggressors in the PC data than in the MC data (attracted: 22.0% vs dispersed: 5.7%; Wilcoxon signed-ranks test: n=15, T=7, P<0.005). Using the time rule, the temporal distribution of the first affiliative interactions between former opponents in the PC data was significantly different from that in the MC data (Fig. 1; Kolmogorov–Smirnov test; Dmax=0.407, v2=9.55, df=2, P<0.05). The greatest difference in the cumulative distributions was at the end of the second minute. This result was not a product of the extreme behavior of a few individuals, as most focal individuals were involved in affiliation with former opponents more often in the first 2 min of PC data than in the first 2 min of MC data (15.7 vs 2.2%; Wilcoxon signed-ranks test: n=16, z=)3.233, P=0.0012). The mean of the individual CCT was 14.4% (SD=15.7%), and the CCT at the group level was 15.5% (attracted =42, dispersed =10, total =206). The average latency to reconciliation was about 98 s. Reconciliation was initiated by the aggressor in 16 out of 44 cases (37%), by the victim in 27 cases (61%), and by both opponents in one case (aggression between adult females). Although increased PC affiliation between former opponents might be merely a by-product of a general increase in PC affiliation, this possibility can be rejected, as there was no increase in the overall rate of affiliation with all group members in the PC period (PC data: 0.06, MC data: 0.06 affiliative partners/min; Wilcoxon signed-

Fig. 1 Temporal distribution of the first affiliation between opponents following an aggressive conflict (PC: n=44) and in the baseline condition (MC: n=15)

ranks test: n=17, z=)0.181, P=0.86), and the proportion of the victim’s affiliative interactions that involved the former aggressor was greater in PC data than in MC data (39.1 vs 22.2%; n=14, T=19, P=0.035). In a wild group, it is also possible that opponents did not affiliate because they were farther apart in the MC data than in the PC data. Therefore, we compared the affiliation rates in PC data with MC data in which the initial distance between opponents was either identical or larger in the former than in the latter (note that this analysis is strict in terms of detecting selective affiliation in the PC data). Again, affiliation with the former aggressor occurred significantly more often in the PC data than in the MC data (18.1 vs 7.0%; Wilcoxon signed-ranks test: n=15, T=13.5, P=0.009). Combined, these results demonstrate that former opponents contacted each other sooner in the PC data than in the MC data, and that the increase in PC affiliation was highly selective. Factors influencing the occurrence of reconciliation To investigate the factors affecting the occurrence of reconciliation, we compared the conciliatory tendency of various classes. Since the sample size for aggression between related individuals was small (n=11), we excluded those data from the analysis. Owing to the limited sample size, we could not investigate the influences of dyadic/polyadic aggression, or the outcome of the aggression (decided/undecided). In unrelated dyads, we found that chimpanzees reconciled more frequently after aggression with physical contact (30.6%) than after non-physical aggression (16.8%; T=4, n=8, P=0.05). However, conciliatory tendencies did not differ according to other factors, such as the age combination of the opponents (adult–adult vs adult–adolescent or juvenile:

161

among the females with regard to different classes of CCTs (i.e., between males or between a male and female). However, as our data did not include aggression between natal females, this consideration does not apply. Overall, our data suggest that reconciliation patterns in Mahale chimpanzees are not in accord with the valuable relationship hypothesis.

23.3 vs 19.4%; T=25, n=11, P=0.50), sex combination (male data: against male vs against female: 29.7 vs 20.6%, T=5, n=5, P=0.50; female data: against male vs against female; 25.8 vs 26.4%, T=4, n=5, P=0.72; male and female data: male–male vs female–female: 29.7 vs 26.4%: Mann–Whitney U-test, nmale=nfemale=5, U=10.5, P=0.67), initial distance between the opponents at the end of aggression (within 5 m vs more than 5 m; 16.5 vs 25.5%; T=23, n=11, P=0.37), or association level (affiliative vs neutral: 16.8 vs 9.7%; T=22, n=10, P=0.57; note that we excluded the aggression between non-affiliative individuals due to the small sample size). As reported above, neither sex combination nor association level between the opponents influenced the occurrence of reconciliation; this finding does not support the valuable relationship hypothesis. To investigate this hypothesis in more detail, we re-compared the influences of sex combination and association level between opponents using only data for aggression between adults. Owing to the small sample size, we calculated the CCT from pooled data for each class, and compared CCTs by the v2-test. As a result, CCT differed among the three categories of association level (v2-test: P<0.013) but did not differ by sex combination (v2-test: P=0.60; see Table 2). With respect to the influence of association level, CCT between non-affiliative dyads showed the highest figure, as compared to different classes of CCT; this result does not support the valuable relationship hypothesis. With respect to the influence of sex combination, some females born in the M-group remained in the group after sexual maturity in Mahale (Nishida et al. 2003), which might be thought to have influenced the similar level of conciliatory tendency

PC third-party affiliation We classified PC affiliation involving a third party on the basis of who initiated the affiliation (the opponent or the third party), and investigated its occurrence by comparing PC and MC data. Table 3 summarizes the results. We found that an affiliation on the part of a third party, with respect to the victim and the aggressor, occurred more frequently in the PC data than in the MC data (Fig. 2). A time rule method did not reveal significant differences in the temporal distribution of all types of PC interaction between the PC and MC data (Table 3). Excluding PC–MC data in which renewed aggression occurred in the PC data did not affect the result. A difference in the availability of a third party between the PC and MC data could cause this result. For example, PC third-party affiliation might be statistically detected because a third party was more often available in the PC data than in the MC data. To test this possibility, we excluded the opponent as an affiliation partner and re-ran the analysis of the overall rate of affiliation with group members in the PC period. We found a nonsignificant difference in the number of affiliation partners in the PC and MC data (0.03 vs 0.03; z=)0.028, n=17, P=0.98). This suggests that the availability of a third party did not differ in the PC and MC data. Due to the small sample size, we pooled the data in subsequent analyses. In PC third-party affiliation, affiliation by a third party who was non-affiliative to the opponents was rarely observed (Table 3). This suggests that less-associated individuals rarely engage in PC third-party affiliation. With regard to this result, it is possible that the statistical detection of two kinds of third-party-initiated affiliation could be caused by a difference in the availability of a third party in the PC and MC data. For example, one might compare the PC events with a MC in which there was no suitable third party. To exclude this possibility, we excluded MC data

Table 2 CCT between adults. CCT = (No. of attracted pairs) No. of dispersed pairs)/total number of PC–MC pairs CCT (%) v2 P

No. of pairs Attracted Dispersed Total Male–male 9 Male–female 21 Female–female 5

2 6 1

51 67 19

13.7 22.4 21.1

1

0.6

Affiliative 18 Neutral 10 Non-affiliative 7

4 5 0

65 59 13

21.5 8.3 53.8

8.8 <0.013

Table 3 The occurrence of third-party PC affiliation. When one type of PC affiliation occurred more often following aggression (PC) than during corresponding baseline condition (MC), the association level between the focal individual and the affiliation partner was noted PC affiliation Initiator Receiver PC–MC method

Time rule method Affiliation partner

Attractive (%) Dispersed (%) n Solicited consolation Consolation – Appeasement

Vic

Third

6.4

9.2

Third Agg Third

Vic Third Agg

22.2 9.1 27.6

7.1 11 8.2

T

P

v2

Dmax P

7 11.5 0.612 2.562 0.25 10 0 9 15 10 0

Affiliative Neutral Non-affiliative

0.139

0.028 0.727 0.167 0.348 16 0.674 0.593 0.173 0.372 0.011 1.687 0.232 0.215 15

8

0

11

1

162 Fig. 2a, b Temporal distribution of the first affiliation involving a third party following aggression (PC) and in the baseline condition (MC). Directed from a third party a towards the aggressor (‘‘appeasement’’; PC: n=27, MC=11), and b towards the victim (‘‘consolation’’; PC: n=24, MC=9)

in which affiliative and neutral group members were not in proximity to the focal individual and investigated the occurrence of appeasement and consolation again. Note that this analysis makes detection of the occurrence of PC third-party affiliation less likely, because there were incidents in the PC data in which the focal individuals did not meet affiliative or neutral group members. We found that the rate at which a third party affiliated to the victim (PC vs MC: 24 vs 9 cases; Fisher’s exact probability test: P=0.025, n=97) and to the aggressor (PC vs MC: 26 vs 9 cases; Fisher’s exact probability test: P=0.009, n=88) was significantly higher in the PC than in the MC data. This suggests that the demonstration of appeasement and consolation in previous analyses was not due to differences in the third-party characteristics.

P=0.008), and the difference approached the corrected level of significance. This suggests that gentle touching may be a behavior that is specific to reconciliation. Note that allo-grooming occurred more frequently in the MC data than in the PC data (v2-test; P=0.014) and this difference also approached the corrected significance level. This suggests that allo-grooming may not be reconciliation behavior in this group. We could not find corresponding affiliative interactions with an affiliation partner in the PC and MC data, so we could not compare the incidence of specific behaviors (Table 4) in PC third-party affiliation.

Discussion The occurrence of reconciliation

Behavior specificity in reconciliation and PC third-party affiliation We investigated what types of behavior were used in reconciliation and other PC affiliations (Table 4). Because multiple comparisons were conducted, we employed the strict significant level by Bonferroni correction (0.0063 = 0.05/8). In reconciliation, gentle touching occurred frequently in the PC data, as compared to the MC data (Fisher’s exact probability test; Table 4 The proportion of affiliative behavior in the first affiliation between former opponents (reconciliation) following aggression (PC) and corresponding baseline condition (MC). Chi-square test or Fisher’s exact test was used for comparison of PC and MC. Concerning appeasement and consolation, only the proportion in PC were described. Significance level = 0.0063 (see text)

Behavioral type

Allo-grooming Kissing Gentle touching Genital checking Embracing Grasping the testicles Playing Contact sitting Mounting

This study showed that opponents affiliated selectively following aggressive interactions, which suggests that reconciliation occurred in this group. The mean of the individual CCT was 14.4% (group conciliatory tendency: 15.5%), which is similar to the level seen in wild groups (12.3%: Arnold and Whiten 2001; 15.9% for group CCT at Tai: Wittig, personal communication), and in captive groups in the Detroit Zoo (14.4%: Baker and Smuts 1994; see also Fuentes et al. 2002), and at

Reconciliation 2

PC (%, n=44)

MC (%, n=15)

v

P

20.5 9.1 50 2.3 6.8 2.3 4.5 4.5 –

80 6.7 13.3 0 0 0 0 0 –

5.62 – – – – – – – –

0.014 >0.99 0.008 >0.99 >0.99 >0.99 >0.99 >0.99 –

Appeasement (n=27)

Consolation (n=24)

44.4 7.4 29.6 3.7 – – 3.7 7.4 3.7

50 – 16.7 – – – – 20.8 12.5

163

CHCI (20.6%: Fuentes et al. 2002), but less than half of that seen in the Arnhem and Yerkes groups (27–35%: de Waal and van Roosmalen 1979, see also Fuentes et al. 2002—note that de Waal and van Roosmalen (1979) used a conciliatory tendency that did not consider the baseline affiliation level; 41%: Preuschoft et al. 2002). In addition, the CCT seen in the present study is relatively low compared to that in previous reports on various primate species (reviewed in Aureli and de Waal 2000). Since it has been argued that a group’s conciliatory tendency reflects the dominance style within the group (Castles et al. 1996), the low conciliatory tendencies seen in wild chimpanzees seem to disabuse the general notion that chimpanzee societies are relatively tolerant (e.g., Goodall 1986; de Waal and Aureli 1996). For wild primates, it is possible for opponents to avoid interacting with each other following aggression as a means of conflict modulation, instead of reconciling (Sommer et al. 2002). In particular, the effect of living conditions may be extremely strong for wild chimpanzees, since they live in a fission–fusion society, and this may be responsible for the relatively low tendency towards reconciliation in wild chimpanzees as compared to that observed in captive conspecifics. This study did not support the valuable relationship hypothesis, as the CCT was no higher between individuals who shared valuable relationships (males or affiliative dyads) than between individuals who did not (females or less-associative dyads), even after focusing on aggression between adults. We should be cautious when interpreting this result, as this study is based on a relatively small sample size. Still, it is surprising that unrelated adult females reconciled frequently (21.1%) in the wild condition. This result contrasts with observations of the Budongo group, where females were not observed to reconcile at all (Arnold and Whiten 2001). Some researchers have claimed that the issue of whether female chimpanzees in the wild reconcile constitutes a good test of the valuable relationship hypothesis (‘‘good relationship’’ hypothesis in Kappeler and van Schaik 1992, p. 64). Are the results of this study exceptional? We suggest that they are not, first because it seems premature to conclude that female chimpanzees do not reconcile in the wild, as the Budongo study observed only three cases of aggression between adult females (Arnold and Whiten 2001), and second because less systematically organized studies have also reported that females in wild groups reconcile (Goodall 1986; Muller 2002), which suggests that reconciliation between females is not unusual in other wild groups. Why, then, did the pattern of reconciliation in Mahale not follow the prediction of the valuable relationship hypothesis? It has been said that relationship characteristics other than value, such as low ‘‘security’’ between the opponents (the perceived probability that the relationship with the partner will change), facilitate the occurrence of reconciliation (Cords and Aureli 2000). For example, Cords and Aureli (1993) found that juvenile long-tailed macaques reconciled more often

with ‘‘insecure’’ non-kin than with ‘‘secure’’ kin. In the study group (M-group), female chimpanzees increased their behavioral index of anxiety when a non-affiliative individual was in proximity, suggesting the association level within the group relates to relationship security for females (Kutsukake 2003). Also, it seems that the relationship quality between opponents is influenced by the series of social interactions that has occurred previously between them. This influences the ease with which the partners can interact (‘‘compatibility’’ by Cords and Aureli 2000); such a temporal fluctuation in the quality of the relationship between opponents may affect the occurrence of reconciliation. If such relationship characteristics, in addition to relationship value, constitute a factor in reconciliation among Mahale chimpanzees, the reconciliation pattern might not follow the valuable relationship hypothesis. In this group, the overall behavioral patterns observed in reconciliation did not differ from those seen in general affiliations during the baseline condition. However, gentle touching was seen more frequently in the PC data than in the MC data, and the difference approached the level of significance. In addition, wild chimpanzees in the Sonso group did not show the explicit gesture that is distinct to reconciliation; gentle touching was seen only during reconciliation, and not in the MC data (see Fig. 6 in Arnold and Whiten 2001). These results suggest that wild chimpanzees do not exhibit the affiliative behavior that is specific to reconciliation, or, at best, that gentle touching may constitute a type of affiliative behavior that is specific to reconciliation. Previous research on PC behavior has shown that tolerant species with high conciliatory tendencies tend to adopt a specific behavior for reconciliation, such as kissing in chimpanzees (Arnhem group: de Waal and van Roosmalen 1979; Yerkes group: de Waal and Aureli 1996), the hold-bottom ritual of stump-tailed macaques (de Waal and Ren 1988), and the standing-grasp in pigtailed macaques (M. nemestrina, Castles et al. 1996). As noted above, the tendency towards reconciliation observed in this study and the Sonso group was relatively low, as compared to that observed in the Arnhem and Yerkes groups. Therefore, our results suggest that a group’s conciliatory tendency and the presence or absence of specific behavior during reconciliation are interrelated, not only between different species, but also within a single species. PC third-party affiliation Compared to reconciliation, it has repeatedly been suggested that little attention has been paid to PC interactions involving a third party (Cords 1997; Das 2000; Watts et al. 2000). In this study group, third parties actively affiliated with the opponents after aggression, but the aggressor or victim did not increase affiliation with third parties, as compared to the control period. The occurrence of third-party-initiated affiliation

164

was not caused by differences in the availability of affiliative third parties in the PC and MC data. These results indicate that appeasement and consolation constitute a repertoire of PC behavior in this group. This occurrence of consolation is consistent with the results for the captive Yerkes group (de Waal and Aureli 1996), but contrasts with those for the Budongo Forest group (Arnold and Whiten 2001). This suggests that the presence or absence of PC third-party affiliation is not a stable characteristic of PC behavior in wild chimpanzees. However, our results differ from those for the Yerkes group, in that Yerkes chimpanzees frequently used embracing in consolation, whereas it was not apparent in Mahale. Furthermore, most cases of consolation occurred in the first minute after aggression in Yerkes, whereas we saw no clear temporal distribution pattern in the occurrence of consolation and appeasement. These results suggest that the occurrence of PC third-party affiliation is delayed in the wild; this is in contrast to the clear pattern of reconciliation soon after the end of aggression that has been observed in various other groups. Although we have used the functional terms consolation and appeasement in this study, it should be noted that the function of these behaviors has not been analyzed thus far. Theoretically, PC affiliation with an opponent initiated by a third party could occur when the benefits outweigh the costs to the third party. As a potential cost of these types of PC third-party affiliation, a third party might incur the risk of being involved in renewed aggression through affiliating with, rather than avoiding, opponents, because the initial aggression can lead to subsequent aggressive interaction that includes a third party (snowballing: Goodall 1986, p. 319). As a potential benefit, third parties may be able to alleviate their own stress regarding the risk to themselves of being involved in a renewed attack by the aggressor, or calm the general social tension of the opponents after aggression, thus reducing the probability of a re-occurrence of aggression. In chimpanzees, the costs might be relatively low, in that they live in relatively tolerant societies, in which dominance relationships are relatively symmetrical (de Waal and Aureli 1996). This is the central idea of the social constraint hypothesis, which explains the difference between the occurrence of consolation among chimpanzees and that among other primate species (e.g., macaques) by differences in social style (de Waal and Aureli 1996). It has been predicted that, even within a single species, the costs or benefits of PC third-party affiliation may vary with each aggressive interaction; these differences may lead to PC third-party affiliation in some groups (e.g., M-group in Mahale) but not in others (e.g., the Sonso group in Budongo, Arnold and Whiten 2001). To test this idea, it is necessary to investigate the benefits and costs of PC third-party affiliation, both for the actor (the third party) and for the recipient. Unfortunately, this was not possible in this study because of the small sample size. A future study based on a larger

sample size may clarify these issues, enabling us to understand the function of PC third-party affiliation. Acknowledgments We would like to thank the Tanzanian Commission for Science and Technology, the Serengeti Wildlife Research Institute, the Mahale Mountains Wildlife Research Centre, and Tanzania National Parks for permitting this research and for support while N.K. was in Tanzania. N.K. would also like to thank Toshisada Nishida, Kenji Kawanaka, Shigeo Uehara, Kazuhiko Hosaka, Michio Nakamura, Shiho Fujita, James Wakibara, Takahisa Matsusaka, and Watongwe research assistants, as well as other colleagues of the research team including Chisa Tokimatsu, for their support in various ways. N.K. would like to thank Toshikazu Hasegawa for supervision and support over the course of this study, Keiko Fujisawa for helpful discussions, Roman M. Wittig for sharing information, reviewers for important comments, as well as Toshimichi Nemoto and his family for their support. This study was financially supported by the Monbusho Scientific Research Fund (Basic Research A1, No. 12375003 to T. Nishida) and JSPS Research Fellowships for Young Scientists (to N.K.).

References Altmann J (1974) Observational study of behavior: sampling methods. Behaviour 49:227–265 Arnold K, Whiten A (2001) Post-conflict behaviour of wild chimpanzees (Pan troglodytes schweinfurthii) in Budongo Forest, Uganda. Behaviour 138:649–690 Aureli F, de Waal FBM (2000) Natural conflict resolution. University of California Press, California Aureli F, van Schaik CP, van Hooff JARAM (1989) Functional aspects of reconciliation among captive long-tailed macaques (Macaca fascicularis). Am J Primatol 19:39–51 Aureli F, Cords M, van Schaik CP (2002) Conflict resolution following aggression in gregarious animals: a predictive framework. Anim Behav 64:325–343 Baker KC, Smuts BB (1994) Social relationships of female chimpanzees: diversity between captive social groups. In: Wrangham WW, McGrew WC, de Waal FBM, Heltne PG (eds) Chimpanzee cultures. Harvard University Press, Cambridge, Mass., pp 227–242 Boesch C, Hohmann G, Marchant LF (2002) Behavioural diversity in chimpanzees and bonobos. Cambridge University Press, Cambridge, UK Cairns S, Schwager SJ (1987) A comparison of association indices. Anim Behav 35:1454–1469 Call J, Aureli F, de Waal FBM (2002) Postconflict third-party affiliation in stumptailed macaques. Anim Behav 63:209–216 Castles DL, Aureli F, de Waal FBM (1996) Variation in conciliatory tendency and relationship quality across groups of pigtail macaques. Anim Behav 52:389–403 Cords M (1997) Friendship, alliances, reciprocity, and repair. In: Whiten A, Byrne R (eds) Machiavellian intelligence II: evaluations and extensions. Cambridge University Press, Cambridge, pp 24–49 Cords M, Aureli F (1993) Pattern of reconciliation among juvenile long-tailed macaques. In: Pereira ME, Fairbanks LA (eds) Juvenile primates—life history, development, and behaviour. Oxford University Press, Oxford, pp 271–284 Cords M, Aureli F (2000) Reconciliation and relationship quality. In: Aureli F, de Waal FBM (eds) Natural conflict resolution. University of California Press, California, pp 177–198 Das M (2000) Conflict management via third parties: post-conflict affiliation of the aggressor. In: Aureli F, de Waal FBM (eds) Natural conflict resolution. University of California Press, California, pp 263–280 Fuentes A, Malone N, Sanz C, Matheson M, Vaughan L (2002) Conflict and post-conflict behavior in a small group of chimpanzees. Primates 43:223–236

165 Goodall J (1986) The chimpanzees of Gombe: patterns of behaviour. Belknap, Cambridge Kappeler PM, van Schaik CP (1992) Methodological and evolutionary aspects of reconciliation among primates. Ethology 92:51–69 Kutsukake N (2003) Assessing relationship quality and social anxiety among wild chimpanzees using self-directed behaviour. Behaviour 140:1153–1171 Kutsukake N, Castles DL (2001) Reconciliation and variation in post-conflict stress in Japanese macaques (Maraca fuscata fuscata): testing the integrated hypothesis. Anim Cog 4: 259– 268 Kutsukake N, Matsusaka T (2002) Incident of intense aggression by chimpanzees against an infant from another group in Mahale Mountains National Park, Tanzania. Am J Primatol 58:175–180 Matsumura S (1996) Postconflict affiliative contacts between former opponents among wild moor macaques (Macaca maurus). Am J Primatol 38:211–219 Muller MN (2002) Agonistic relations among Kanyawara chimpanzees. In: Boesch C, Hohmann G, Marchant LF (eds) Behavioural diversity in chimpanzees and bonobos. Cambridge University Press, New York, pp 112–124 Newton-Fisher NE (1999) Association by male chimpanzees: a social tactic? Behaviour 136:705–730 Nishida T (1990) The chimpanzees of the Mahale Mountains: sexual and life history strategies. University of Tokyo Press, Tokyo Nishida T, Corp N, Hamai M, Hasegawa T, Hiraiwa-Hasegawa M, Hosaka K, Hunt KD, Itoh N, Kawanaka K, MatsumotoOda A, Mitani JC, Nakamura M, Norikoshi K, Sakamaki T, Turner L, Uehara S, Zamma K (2003) Demography, female life history, and reproductive profiles among the chimpanzees of Mahale. Am J Primatol 59:99–121

Preuschoft S, Wang X, Aureli F, de Waal FBM (2002) Reconciliation in captive chimpanzees: a reevalution with control methods. Int J Primatol 23:29–50 Sommer V, Denham A, Little K (2002) Postconflict bahaviour of wild Indian langur monkeys: avoidance of opponents but rarely affinity. Anim Behav 63:637–648 Veenema HC, Das M, Aureli F (1994) Methodological improvements for the study of reconciliation. Behav Process 31:29–38 de Waal FBM (1986) The integration of dominance and social bonding in primates. Q Rev Biol 61:459–479 de Waal FBM (2000) Primates: a natural heritage of conflict resolution. Science 289:586–590 de Waal FBM, Aureli F (1996) Consolation, reconciliation, and a possible cognitive difference between macaques and chimpanzees. In: Russon AE, Bard KA, Parker ST (eds) Reaching into thought: the minds of the great apes. Cambridge University Press, Cambridge, pp 80–110 de Waal FBM, Ren R (1988) Comparison of the reconciliation behavior of stumptail and rhesus macaques. Ethology 78:129– 142 de Waal FBM, van Roosmalen A (1979) Reconciliation and consolation among chimpanzees. Behav Ecol Sociobiol 5:55–66 de Waal FBM, Yoshihara D (1983) Reconciliation and redirected affection in rhesus monkeys. Behaviour 85:224–241 Watts DP, Colmenares F, Arnold K (2000) Redirection, consolation, and male policing: how targets of aggression interact with bystanders. In: Aureli F, de Waal FBM (eds) Natural conflict resolution. University of California Press, California, pp 281– 301 Wittig RM, Boesch C (2003) ‘‘Decision-making’’ in conflicts of wild chimpanzees (Pan troglodytes): an extension of the relational model. Behav Ecol Sociobiol 54:491–504

Reconciliation and post-conflict third-party affiliation ...

Apr 28, 2004 - following aggression in gregarious animals: a predictive framework. ... Whiten A, Byrne R (eds) Machiavellian intelligence II: evalu- ations and ...

263KB Sizes 1 Downloads 171 Views

Recommend Documents

Affiliation Networks
Jun 2, 2009 - perties of the social networks, as well as densification and ... [10] made a rich .... ships among people often stem from one or more common or.

Stress and syncope Author's affiliation
syncope in pitch accent systems like Japanese (Bennett [Archangeli] 1981) or .... (abbreviated *V-PLweak), which is violated by a place-bearing vowel in either ...

Roster Reconciliation - MOBILPASAR.COM
b) Amount from BUDGET05 Detail Permanent Budget Transactions for Roster. Reconciliation report (BDM2). 3) Other adjustments and PAR's submitted to ...

Stress and syncope Author's affiliation - Semantic Scholar
Author's affiliation: University of Massachusetts Amherst. Author's .... Constraint-Ranked Derivation (Black 1993), Constraint Cumulation Theory (Norton 2003), and the OT syllable ...... thesis, University of California, Santa Cruz. [Available at.

The Annual ANU Reconciliation Lecture 2011 Reconciliation in an era ...
a common culture which is shared through social media. Another is that people ... Professor Tim Flannery is one of Australia's leading writers on climate change.

Reconciliation, submission and avoidance
Saitama, 351-0198, Japan (email: [email protected] or kutsu@ · darwin. .... from nine to 36 individuals in 2003 (median ¼ 19) and from eight to 38 individuals ...

Stress and syncope Author's affiliation - Semantic Scholar
imaginable ways of defining this limit, and faithfulness theory offers a good ..... original host is deleted (Goldsmith 1976). ..... stress domain with the host word.

The Annual ANU Reconciliation Lecture 2011 Reconciliation in an era ...
One important aspect is that people (the young in particular) are adopting a common culture which is shared through social media. Another is that people are ...

pdf-1893\truth-and-indignation-canadas-truth-and-reconciliation ...
... the apps below to open or edit this item. pdf-1893\truth-and-indignation-canadas-truth-and-recon ... ial-schools-teaching-culture-utp-ethnographies-for.pdf.

bank reconciliation statement pdf
Sign in. Loading… Whoops! There was a problem loading more pages. Retrying... Whoops! There was a problem previewing this document. Retrying.

TIF-Reconciliation-Report.pdf
Sign in. Page. 1. /. 34. Loading… Page 1 of 34. Page 1 of 34. Page 2 of 34. Page 2 of 34. Page 3 of 34. Page 3 of 34. TIF-Reconciliation-Report.pdf. TIF-Reconciliation-Report.pdf. Open. Extract. Open with. Sign In. Main menu. Page 1 of 34.

pdf-1488\shared-identity-and-reconciliation-can-a-future-security ...
... the apps below to open or edit this item. pdf-1488\shared-identity-and-reconciliation-can-a-futur ... raw-from-experiences-of-the-north-atlantic-security.pdf.

Reconciliation and variation in post-conflict stress in ...
Nov 1, 2001 - have two functions: (1) to repair relationship damaged by aggression such that .... (SDB), such as scratching, auto-grooming, and yawning, is associated with .... begun within 15 min (either side) of the start time of the PC. MCs ... Wh

Reconciliation pattern after aggression among ...
there is a risk of aggression with continued interaction [Hartup, 1992]. Therefore, friends ... a predictive framework. .... management in children and adolescents.

Cash Box Reconciliation Form.pdf
forms equation of line. ft only on their gradient. (ii) x y = → = += 0.5 ln 4 3 3 9.928. y = 20 500. M1. A1. correct expression for lny. (iii) Substitutes y and rearrange for 3x. Solve 3x. = 1.150. x = 0.127. M1. M1. A1. Page 3 of 10. Cash Box Reco

The neuroscience of affiliation
involved in the retention and preservation of social memory acquisition in autism. ..... identify other mechanisms to deliver oxytocin into the brain. As noted, it is ...

Scaling and statistical models for affiliation networks
statistical approaches in the social sciences on a par with models and scientific ... methods and random graph methods, two methods for modeling affiliation ...

Cash Box Reconciliation Form.pdf
www.myschoolchildren.com. Muat turun (percuma) kertas soalan lain di : Page 1 of 1. Cash Box Reconciliation Form.pdf. Cash Box Reconciliation Form.pdf.

Act for Equal Employment and Support for Work- Family Reconciliation ...
There was a problem previewing this document. Retrying... Download. Connect more apps... Act for Equal ... ation 2011.pdf. Act for Equal E ... iation 2011.pdf.

Reconciliation and variation in post-conflict stress in ... - baillement.com
Nov 1, 2001 - have two functions: (1) to repair relationship damaged by aggression such .... (SDB), such as scratching, auto-grooming, and yawning, is associated with ..... culated individuals' mean rates of each class of SDB (in bouts per.

Cash Box Reconciliation Form.pdf
Cash Box Reconciliation Form.pdf. Cash Box Reconciliation Form.pdf. Open. Extract. Open with. Sign In. Main menu. Displaying Cash Box Reconciliation ...