Agonism, Affiliation, and Social Organization in a Community of Savanna Chimpanzees (Pan troglodytes verus) at Fongoli, Senegal

This dissertation illuminates the structure of social life in a community of savanna chimpanzees at Fongoli, Senegal. Where this study differs from some others is that in addition to conspicuous and active acts of affiliation and aggression, subtler social phenomena were also recorded. The commonness, context, and intensity of these various behaviors are described in detail and compared to other study sites when data are available. The first part of the dissertation sets up a theoretical and methodological framework for the study of patterns of social behavior in chimpanzees. Chapter 1 provides a summary of the use of chimpanzees as proxies for humans and theories explaining lethal aggression in these two species. Chapter 2 describes the particulars of the Fongoli study site and community, as well as basic data collection methods. In Chapter 3, conceptions of aggression, social hierarchy, and conflict are discussedin particular, differentiating aggression directly tied to hierarchy in a narrow sense from that tied to it only broadly. In Chapter 4, methods of data collection and analysis are explained with regard to contact aggression specifically. The second part of the dissertation covers data analysis and interpretation. In Chapter 5, patterns of contact aggression at Fongoli are described and compared to published data from other sites. In Chapter 6, patterns of the basic activity budget and social behavior other than contact aggression and copulation are examined. In Chapter 7, copulation patterns are discussed. In Chapter 8, results are summarized and discussed in connection with broad theoretical concerns such as the social bauplan, affect hunger, the concept of competition, social hierarchy as right-of-way, organizational change as rites of passage, an alternative to lethal aggression as adaptive behavioral trait, and how dynamic social systems are structured and change. Summarizing patterns of social behavior at Fongoli, affiliation rather than aggression was an all-consuming aspect of chimpanzee life. Aggression was rare and, like high dominance rank, was not associated with copulation success. Therefore, dominance-submission roles served as a sort of right-of-waya way to avoid deleterious conflict which benefited all membersnot just those of high rank. Also, dominance in one sphere did not necessarily carry over into others. Aggression with physical contact was particularly rare, was generally of low intensity, and seemed most proximately tied to spatial friction rather than to attempts to monopolize resources, i.e., competition. In each of the few instances of severe intensity contact aggression, it was associated with potential restructuring of the male dominance hierarchy, such as in changes in alpha status and the transition from adolescence into adulthood. It appears that as role certainty or familiarity decreases, the intensity of aggression increases. Further, separate adaptive explanations for lethal aggression (not observed during this study) within communities during periods of particular social instability, or towards individuals from other communities or those living peripherally, are not required. The difference between severe and lethal aggression is likely one not of kind, but of degree