Apes use gestures in an intentional and highly flexible manner. It has been proposed that human language originated in gestural communication and therefore ape gestures have been of great interest to primatologists and psychologists alike. The extensive, flexible and intentional nature of ape gestural communication may also provide new insights to the study of social regulation as large communicative systems are thought to be useful in navigating complex social landscapes. To date studies of bonobos and their use of gestures has occurred in limited contexts and therefore the known repertoire of bonobos is relatively small. It is also unknown as to what bonobos use gestures for and whether they use those gestures flexibly in order to regulate their social relationships. To investigate these questions I studied a captive population of bonobos for 12 months at the Milwaukee County Zoo, Wisconsin, USA. Milwaukee bonobos used 55 gesture types over the course of the study period. I found that bonobos have particular goals behind their signalling and that bonobos used gestures consistently for specific goals and that the same gestures were used for the same goals across signallers. It was therefore possible to identify to meanings behind over half of the gestures within the bonobo repertoire. Even though the meanings of gestures were consistent across signallers, the age and sex of a signaller influenced what context and for what purpose he or she used gestural communication. Particular types of signallers used gestures for particular goals and directed those gestures towards particular recipients. Bonobos also used gestures within dialog during special circumstances in order to coordinate asymmetrical interactions. These results indicate that gestural communication is an excellent medium for investigating the influence a large, intentional and flexible communication system has on managing a complex social network.

xvii, 149 p. : ill. (some col.), maps / The ranging behavior of an animal can reveal much about the social and ecological conditions it faces. Food availability, feeding competition, population pressures, metabolic requirements and human influences can all influence the ranging behavior of individuals. For modern humans, the manner in which we move about our world is limited only by access to technology and other cultural factors. Of course, it has not always been that way. Based on recent fossil discoveries, our earliest bipedal ancestors more closely resembled the living great apes in morphology. Consequently, studies of great ape behavior have been used to reconstruct scenarios of early hominin behavior. And while much has been written about chimpanzee ( Pan troglodytes ) ranging in this regard, less is known about bonobos (Pan paniscus ). Along with chimpanzees, bonobos are our closest phylogenetic relative, existing today as a descendant of a common ancestor the Homo and Pan genera shared sometime around six million years ago. Despite their close taxonomic relationship, however, there are a variety of behavioral differences between bonobos and chimpanzees. The aim of this dissertation is to better understand these differences within the context of ranging and social behavior and apply the results to models of early hominin behavior. More specifically, I used a Geographic Information Systems (GIS) approach to examine general bonobo ranging data, the differences in ranging behavior between males and females, and the manner in which neighboring groups interact. Compared with chimpanzees, bonobos at Lomako range over a much smaller total area, are not territorial, and differ in the composition of social parties. In general, female bonobos are more gregarious and cohesive, moving in semi-stable groups I call "cliques", while males are less aggressive and more likely to move independently. These results likely reflect the high levels of food availability for bonobos at Lomako, reducing the level of feeding competition, and emphasizing social and mating strategies in group formation. Consequently, the spectrum of potential early hominin ranging behavior must be expanded from the current chimp-centric perspective. / Committee in charge: Frances White, Chairperson; Stephen Frost, Member; Larry Sugiyama, Member; James Schombert, Outside Member