field_laptop1I am a quantitative social scientist who uses mathematical models and ethnographic field research to understand human ultrasociality – our ability to organize ourselves into societies capable of large-scale cooperation and large-scale conflict – especially in the contexts of war, political organization, and environmental sustainability.

My mathematical modeling uses evolutionary game theory to answer questions like: Why do people cooperate in one-shot economic experiments? Why are humans the only species to cooperate with non-kin in high-risk warfare? How do ideas contribute to international conflict? Where does hierarchical organization come from? Will known mechanisms of cooperation solve climate change? Why do female dolphins and chimpanzees learn to use tools better than males? Evolutionary game theory is a toolkit that I like to use to solve a wide variety of puzzles.

Recently, I have started to research how the origins of ultrasociality influence our psychology, specifically combat stress and moral injury. I am conducting ethnographic fieldwork with Turkana pastoralist warriors in northern Kenya. Turkana warriors organize large battle raids without the aid of hierarchical institutions and have a high degree of combat exposure – with about half of adult male mortality due to combat. I have interviewed hundreds of warriors about their combat exposure, moral beliefs about warfare, combat stress symptoms, and moral injury.

I am currently a Donald R. Beall Defense Fellow at the Naval Postgraduate School in Monterey, California.

Previously, I was a postdoctoral research fellow at ASU’s Institute of Human Origins and a member of  the Adaptation, Behavior, Culture and Society research group in the School of Human Evolution and Social Change.  Before that, I was a postdoctoral researcher at the National Institute for Mathematical and Biological Synthesis and, before that, a member of the Cultural Evolution and Human Behavioral Ecology Labs at the University of California, Davis.