Macaques (Macaca) are the most geographically widespread and behaviourally diverse primate genus, and although macaque species share the same basic social structure, they display broad interspecific variation in patterns of social behaviour. Based on these patterns, macaque species have been arranged along a 4-grade scale for social style. At one end of the scale, there are grade 1 species (e.g., Japanese macaques) that have highly hierarchical and despotic social systems, and at the other end, grade 4 species (e.g., Tonkean macaques), that have more relaxed and egalitarian social systems. In this study, the play fighting of juvenile Tonkean and Japanese macaques was compared to determine whether or not play behaviour co-varies in a manner similar to that of adult social behaviour. As predicted, Tonkean macaques exhibit a relatively cooperative style of play fighting, whereas Japanese macaques exhibit a relatively competitive style of play fighting. / x, 174 leaves : ill. ; 29 cm. --

The prevalence of play in the animal kingdom makes it a well-studied phenomenon, yet little is known about play fighting behavior in bears. I investigated the effects of sex, partner (dam or cub), and early rearing conditions on play fighting behavior in giant panda cubs by observing video tapes that were recorded at two facilities in China over a three-year period. Two of the three factors, sex and partner, had significant effects on the play fighting behavior of giant panda cubs. I found sex differences in play fighting, with males exhibiting significantly higher rates of biting behavior than females during play bouts with other cubs. This lends support to the motor training hypothesis and suggests that there is a relationship between adult roles and earlier play fighting behavior. Partner had a significant effect on play fighting, in that cubs exhibited significantly higher rates of Bite, Break Away, Paw Swat, and Re-engage behaviors during play bouts with cubs. These differences suggest that cubs and dams might provide different opportunities as partners during play fighting bouts. Because some behaviors occurred at higher rates with dams, it is possible that dams engage in self-handicapping behavior during play fighting bouts with cubs. Early rearing conditions did not have significant effects on behaviors when they were examined by category or by individual behaviors. Similar results were found when cubs that had access to adult females after six months of age were excluded from the analyses. These results suggest that early rearing conditions have little effect on the play fighting behavior of captive giant panda cubs. Certain aspects of giant panda behavioral ecology, however, might contribute to stability in play signals, regardless of early rearing conditions. Future studies of play fighting behavior in bears should further examine these and other factors, and that data from these studies need to be interpreted in light of the relationship of bears to other carnivores.

The research aims of this thesis are to investigate the attention cues available to and used by apes, especially gorillas (Gorilla gorilla), to ascertain the direction of conspecific attention during social interactions with a special reference to social play. Minimal research has been conducted on the role of attention cues - eye gaze, head, and body orientation - to regulate natural social interactions, such as social play, in non-human primates. This thesis begins with an investigation of the "cooperative eye hypothesis", which poses that humans have evolved a unique white sclera adaptation for advertising and detecting gaze direction. Chapter 2 reports the existence of a natural white sclera variation in a proportion of gorilla eyes - contradicting the widely held assumption that white sclera is an exclusively human characteristic - and analyzes the presence of white sclera in relation to other morphological changes in the human eye. The study concludes that the morphological elongation of the eye might be a more important and unique change than the white sclera coloration. Chapter 3 experimentally explores the contribution of white sclera in both great ape and human eye gaze to the perception of gaze direction detection by human observers. This chapter concludes that although white sclera contributes to the accuracy and speed of gaze direction detection (an assumption that this thesis has put to experimental test for the first time), this merely adds to the already efficient gaze cues available in the eye areas of the ape face. Chapter 4 investigates the role of eye gaze, head, and body orientations during gorilla social play behavior, and more specifically, introduces a novel analysis of "vigilance periods" (VPs), in which gorillas may use the interaction between attention cues to gauge the attention and intentions of play partners to successfully navigate play. The final study (Chapter 5) complements Chapter 4 and investigates the role of gorilla postures, behaviors, and movements during changes in attentional cue orientations. This chapter concludes that gorillas often engage in physical rest during VPs but maintain attentional engagement and can assemble and impart socially relevant information based on the behaviors, movements, and attention orientations of their partner. Together, these studies suggest that attention orientation is conveyed and assessed by gorillas through a variety of interacting cues to navigate and modify social play interactions.

The prefrontal cortex (PFC) has long been thought to be the seat of social behaviours in mammals. Lesions of the orbitofrontal cortex (OFC), a subregion of the PFC, are known to cause social deficits in humans. Interestingly, social deficits are also seen in rats with OFC lesions. Rats that are deprived of peer play during development exhibit behaviour similar to OFC-ablated animals. Another subregion of the PFC, the medial prefrontal cortex (mPFC) is interconnected with the OFC. The mPFC and OFC have been shown to be reciprocally responsive to a variety of inuences, in terms of dendritic morphology. It was hypothesized that social experiences are necessary for the proper development of the OFC, and that, because of the interconnectivity, the mPFC would also be sensitive to social experience. The social condition in which juvenile rats were raised was manipulated, and the OFC and mPFC were shown to be differentially responsive to specific aspects of social experience. It was already known that OFC lesions produce specific social deficits, but the contribution of the mPFC to the production of social behaviour was unknown. To investigate the contribution of the mPFC to the performance of social behaviour, animals were given mPFC lesions, and their social play behaviour was quantified. mPFC-ablated animals had altered play patterns that were distinct from those seen in the OFC-ablated animals. It was concluded that the OFC and mPFC are differentially responsive to social stimuli during development, and that the OFC and mPFC make discrete contributions to the production of social behaviour. The results were interpreted in an evolutionary context. / x, 93 leaves : ill. ; 29 cm.