Doctoral Dissertation Improvement: The Neural Bases of Social Cognition in Chimpanzees (Pan Troglodytes)

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Social complexity has been suggested as the driving force behind increased brain size, one of the hallmarks of human evolution: brains become larger as social groups become more complex, providing greater cognitive power to monitor and manipulate relationships. This study will evaluate that hypothesis by describing patterns of brain activity related to social cognition in chimpanzees (Pan troglodytes) and comparing them with those previously described in the much larger human brain. Functional neuroimaging will be used to compare brain activation during social and non-social cognition in five adult chimpanzees. In the social condition, subjects will view a short video depicting chimpanzees engaged in a social interaction (for instance, grooming or playing), and must then choose between a photo of the same type of interaction and a photo of a different interaction. In the non-social condition, subjects will view videos of chimpanzees engaged in non-social behaviors (for instance, feeding or walking), and must choose a photo of the same behavior. These data will be compared with published reports of human brain activation during similar cognitive tasks. This project will illuminate the origins of the neural bases of social cognition in humans and ask whether the patterns of brain function during social cognition in humans are unique to our species, or shared with our closest living relatives. As chimpanzees are our closest living relatives, direct comparison of human and chimpanzee brains is one of the best ways to examine unique aspects of the human brain. If the chimpanzee brain shows similar patterns of activation in response to social stimuli as those of humans, it would suggest that a socially complex brain may have already been present in our last common ancestor. Conversely, if patterns of activation are different, it would suggest that the two species have diverged and one or both have become specialized in this regard.Intellectual merit: Many similarities have been documented between human and chimpanzee social cognition; however, the study of brain function has not yet been extended to great apes. This study will be among the first to use functional neuroimaging with great apes, providing comparative data to place our knowledge of human brain function and social cognition in an evolutionary framework. Given what we know about the neural bases of human cognition, we can use non-invasive functional neuroimaging methods to augment behavioral data in making inferences about cognition in other species. These data will bridge the gap between studies of behavior and studies of brain morphology in apes.Broader impact: This research is interdisciplinary and collaborative, with implications for several fields. Its results will be disseminated widely in professional conferences and publications. It will advance a new methodology, functional neuroimaging in great apes, allowing the application of neuroscience methods to anthropological questions. The study will provide a potential comparative model for disordered social cognition in humans, and will foster involvement of women in science.