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Menzel, E. W. J. (1971). Communication about the environment in a group of young chimpanzees. Folia Primatol (Basel), 15(3), 220–232.
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de Waal, F. B. (1999). Cultural primatology comes of age. Nature, 399(6737), 635–636.
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Noë, R., de Waal, F. B., & van Hooff, J. A. (1980). Types of dominance in a chimpanzee colony. Folia Primatol (Basel), 34(1-2), 90–110.
Abstract: This study examines to what extent the concept of dominance can be used to describe the social structure of a group of semi-free-living chimpanzees. 15 behavioural variables, based on agonistic, competitive and affinitive behaviour patterns, have been compared with respect to the interindividual directions in which they occurred. In this analysis use was made of indices that reflect the position an individual occupies in the relationship structure. These indices were calculated per individual for all variables and subjected to factor analysis and cluster analysis. As a result, 13 of the variables could be grouped in three categories which have been labelled: (1) agonistic dominance; (2) bluff dominance, and (3) competitive dominance. Whereas the top positions in the hierarchies based on the first two closely related types of dominance were occupied by the adult males, the hierarchy based on the third type was headed by several adult females.
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Koski, S. E., & Sterck, E. H. M. (2007). Triadic postconflict affiliation in captive chimpanzees: does consolation console? Anim. Behav., 73(1), 133–142.
Abstract: Consolation is a triadic postconflict interaction between a conflict participant and an uninvolved third party. The term consolation implies stress alleviation. Consequently, consolation may be an effective mechanism to alleviate postconflict stress. However, this assumption has not been tested. We tested whether consolation alleviates postconflict stress in captive chimpanzees, Pan troglodytes. In addition, we examined whether consolation is a substitute postconflict interaction for reconciliation. We collected 643 postconflict-matched control pairs on aggressees and 576 on aggressors. Consolation occurred equally frequently with aggressees and aggressors. However, we found no evidence that consolation alleviated stress, regardless of the identity of the consoler. In addition, consolation was also directed to conflict participants with no evident postconflict stress. Furthermore, we found no evidence for consolation being a substitute for reconciliation. The occurrence of consolation did not depend on the occurrence of reconciliation and consolation was not more prevalent with the sex class that reconciled less often or had the highest postconflict stress levels. We conclude that consolation is a postconflict interaction in its own right, the function of which is not likely to be connected to stress alleviation of the consoled individual. We propose that the function of triadic postconflict affiliation, previously labelled as consolation, should be reassessed with regard to the third parties' reasons to affiliate with conflict opponents.
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Mitani, J. C. (2009). Male chimpanzees form enduring and equitable social bonds. Anim. Behav., 77(3), 633–640.
Abstract: Controversy exists regarding the nature of primate social relationships. While individual primates are frequently hypothesized to form enduring social bonds with conspecifics, recent studies suggest that relationships are labile, with animals interacting only over short periods to satisfy their immediate needs. Here I use data collected over 10 years on a community of chimpanzees, Pan troglodytes, at Ngogo, Kibale National Park, Uganda, to investigate whether male chimpanzees establish long-term social relationships and to determine the factors that affect variation in relationship quality and the stability of social bonds. Kinship and dominance rank influenced the quality of relationships. Maternal brothers and males of the same dominance rank class groomed each other more equitably than did unrelated males and males that were dissimilar in rank. In addition, males that formed strong social bonds groomed more equitably than did males that displayed weaker bonds. Social bonds were stable over time, with relationships in one year predicting those in subsequent years. Kinship and the quality of social relationships affected bond stability. Maternal half siblings and males that groomed each other equitably maintained longer-lasting bonds than did nonkin and males that groomed each other unevenly. Virtually all of the males established at least one enduring relationship with another individual. The most enduring bonds formed between a few pairs of maternal brothers and dyads that maintained balanced grooming interactions. These results indicate that male chimpanzees maintain long-lasting and equitable social bonds whose formation is affected by maternal kinship and the quality of social relationships.
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Newton-Fisher, N. E., & Lee, P. C. (2011). Grooming reciprocity in wild male chimpanzees. Anim. Behav., 81(2), 439–446.
Abstract: Understanding cooperation between unrelated individuals remains a central problem in animal behaviour; evolutionary mechanisms are debated, and the importance of reciprocity has been questioned. Biological market theory makes specific predictions about the occurrence of reciprocity in social groups; applied to the social grooming of mammals, it predicts reciprocity in the absence of other benefits for which grooming can be exchanged. Considerable effort has been made to test this grooming trade model in nonhuman primates; such studies show mixed results, but may be confounded by kin effects. We examined patterns of reciprocity within and across bouts, and tested predictions of the grooming trade model, among wild male chimpanzees, Pan troglodytes: a system with negligible kin effects. In accord with the model's expectations, we found that some grooming was directed by lower- to higher-ranked individuals, and that, on average, higher-ranked individuals groomed more reciprocally. We found no support, however, for a prediction that more reciprocity should occur between individuals close in rank. For most dyads, reciprocity of effort occurred through unbalanced participation in grooming bouts, but reciprocity varied considerably between dyads and only a small proportion showed strongly reciprocal grooming. Despite this, each male had at least one reciprocal grooming relationship. In bouts where both individuals groomed, effort was matched through mutual grooming, not alternating roles. Our results provide mixed support for the current grooming trade, biological market model, and suggest that it needs to incorporate risks of currency inflation and cheating for species where reciprocity can be achieved through repeated dyadic interactions.
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Lonsdorf, E. V., Ross, S. R., Linick, S. A., Milstein, M. S., & Melber, T. N. (2009). An experimental, comparative investigation of tool use in chimpanzees and gorillas. Anim. Behav., 77(5), 1119–1126.
Abstract: Studies of ape tool use have been conducted in captivity since the early 1900s and in the wild since the 1960s. Chimpanzees are the most prolific tool users among the apes, and are known to use more tools than any other nonhuman animal. In contrast, reports of gorilla tool use are rare both in wild and captive settings. Studies of the processes involved in tool use learning have been limited in the wild by the lack of ability to control several unpredictable variables, and in captivity by tool use opportunities that are often presented in non-naturalistic contexts. We attempted to address both of these limitations by providing naïve subjects with a naturalistic tool use device (built to simulate a termite mound) while housed in a more natural social setting to approximate how learning would occur in the wild. Both gorillas and chimpanzees participated in the experiment to allow comparative analyses of acquisition of tool behaviour and the factors that may affect acquisition. Both species showed low frequencies of interaction with the mound in the baseline condition, before baiting with a food reward. Once baited, chimpanzees both attempted and succeeded to extract the reward more quickly than did gorillas. The number of social group members at the mound was significantly higher for chimpanzees than for gorillas and may have affected skill acquisition. We advocate that comparative approaches to skill acquisition and learning are valuable, but that researchers need to be cognizant of species differences in social structure that may affect results.
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Byrne, R. W., & Bates, L. A. (2006). Why are animals cognitive? Curr Biol, 16(12), R445–8.
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Whiten, A. (2005). The second inheritance system of chimpanzees and humans. Nature, 437(7055), 52–55.
Abstract: Half a century of dedicated field research has brought us from ignorance of our closest relatives to the discovery that chimpanzee communities resemble human cultures in possessing suites of local traditions that uniquely identify them. The collaborative effort required to establish this picture parallels the one set up to sequence the chimpanzee genome, and has revealed a complex social inheritance system that complements the genetic picture we are now developing.
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Whiten, A., Horner, V., & de Waal, F. B. M. (2005). Conformity to cultural norms of tool use in chimpanzees. Nature, 437(7059), 737–740.
Abstract: Rich circumstantial evidence suggests that the extensive behavioural diversity recorded in wild great apes reflects a complexity of cultural variation unmatched by species other than our own. However, the capacity for cultural transmission assumed by this interpretation has remained difficult to test rigorously in the field, where the scope for controlled experimentation is limited. Here we show that experimentally introduced technologies will spread within different ape communities. Unobserved by group mates, we first trained a high-ranking female from each of two groups of captive chimpanzees to adopt one of two different tool-use techniques for obtaining food from the same 'Pan-pipe' apparatus, then re-introduced each female to her respective group. All but two of 32 chimpanzees mastered the new technique under the influence of their local expert, whereas none did so in a third population lacking an expert. Most chimpanzees adopted the method seeded in their group, and these traditions continued to diverge over time. A subset of chimpanzees that discovered the alternative method nevertheless went on to match the predominant approach of their companions, showing a conformity bias that is regarded as a hallmark of human culture.
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