Abstract
Traditional views of cognitive evolution favored a simplistic approach in which the evolution of advanced cognition was considered unique to primate lineages. A recent expansion to non-primates indicates that cognition convergently evolved in several lineages. The social intelligence hypothesis attributes the convergent evolution of cognitive complexity to shared selective pressures imposed by social complexity. According to the social intelligence hypothesis, social individuals benefit from cognitive abilities facilitating social life, and the resultant fitness advantage engenders an evolutionary link, whereby social complexity selectively favors cognitive complexity. The social intelligence hypothesis predicts that social species are cognitively advanced. Although several studies support the presence of advanced cognition in social species, a failure to experimentally compare cognition in closely related social and asocial species has resulted in debate over the selective pressure sociality places on cognitive abilities adapted to the physical environment. The domain specific hypothesis posits sociality bolsters only cognition associated with social challenges. Alternatively, the domain general hypothesis argues the unmatched selective pressures of social complexity favor greater cognitive flexibility and ultimately superior general cognition, including nonsocial cognition (e.g. abilities adapted to the physical environment). The clearest route to resolving domain general/specific debate is through direct comparisons of social taxa and taxa whose evolutionary history is void of the selective pressures of sociality (asocial taxa). My dissertation addressed the domain–general/-specific debate and compared cognition in species exhibiting equivalent ecological complexity but divergent social complexity. I compared cognition in carnivores and expanded research to the genus Panthera, which contains both social (lions; P. leo) and asocial species (tigers [P. Tigris] and leopards [P. pardus]). I first tested the prediction that social species are cognitively advanced and presented lions with cognitive tasks requiring social and nonsocial cognition. In agreement with the social intelligence hypothesis, lions demonstrated advanced cognition in the forms of novel problem solving, learning, memory, and cooperation. I next compared cognition among social and asocial carnivores. I presented spotted hyenas (Crocuta crocuta; social), lions (social), tigers (asocial), and leopards (asocial) with a task requiring nonsocial cognition in the form of innovation. My findings support the domain general hypothesis and social carnivores significantly outperformed asocial carnivores.