The evolution of social behavior can affect brain size: social species of animals tend to have larger brains than their solitary relatives. The goal of this project is to further our understanding of how changes in species' social structure can affect the architecture of their brains. The research will use social insects - paper wasps - as subjects. All species of paper wasps are social, but they show a wide range of colony sizes, they are diverse in social complexity, and they differ in nest architecture. Different anatomical regions of the wasp brain serve distinct cognitive functions - some regions are dedicated to vision, others to smell and touch. The researchers will measure the sizes (volumes) of these brain regions as a way of estimating how much tissue is invested in each region, and they will test whether the details of a species' social behavior (for example, large versus small colonies) predict the relative size of each brain region. The researchers will use information on how wasp species are related to each other to trace the evolution of associations between brain structure and behavior. By comparing selected species of paper wasps with different behavioral characteristics, the researchers will determine which elements of social behavior have impacted the investment in each brain region. The project will also explore how evolutionary changes in the immature development of the wasp brain have led to the observed patterns of adult brain region investment. The research will further our understanding of how changes in social complexity can influence brain architecture, and the findings will indicate which social cognitive challenges can affect the amount of investment in different brain regions. It will also contribute to our understanding of how adult brain architecture is generated by the developmental processes that occur during immature stages. The project includes employment and training opportunities for graduate and undergraduate students at two universities, and it will foster collaboration across universities. It also involves both local elementary school and international outreach and education efforts.