Interdisciplinary Behavioral Science
Research
I study the evolved psychological and cultural mechanisms that make large-scale human cooperation possible. My work asks how social influence is distributed, how norms are enforced and transmitted, and how people manage risk through their relationships. I approach these questions with adaptationist, behavioral ecological, and cultural evolutionary theory. The empirical work draws on long-term fieldwork in southwest Ethiopia and comparative analysis of global ethnographic datasets, both analyzed through quantitative and computational modeling.
Leadership & Coordination
How do communities decide who leads, and what do leaders actually do? My fieldwork among the Chabu and Hamar of southwest Ethiopia, combined with cross-cultural analyses across scores of societies, shows that leadership is neither universal in form nor reducible to a dominance vs. prestige dichotomy. I developed the Multi-Capital Leadership Theory, which treats leadership as grounded in four forms of capital: material, social, somatic, and neural. Different ecologies and group demands favor different capital "portfolios."
Norms & Cultural Transmission
How are cooperative norms enforced, taught, and stabilized across generations? My comparative work shows that socioecological factors (particularly inequality and economic intensification) predict variation in punishment systems more strongly than shared cultural ancestry. The Leader-Directed Teaching Hypothesis I recently advanced positions community leaders as central agents in transmitting opaque cooperative norms through active teaching. This links social influence to the cultural stability of cooperation.
Social Networks & Risk
How do individual decisions about relationships scale into network structures that shape coordination, conflict, and resilience? Through an NSF Human Networks and Data Science grant, I co-direct a multi-site longitudinal study of interethnic networks across four pastoralist communities in Ethiopia's Omo Valley. Early results show that intercultural and inter-gender ties form even within strongly patriarchal settings, suggesting one way relational structures buffer risk and sustain cooperation under ecological and economic pressure.
Health & Inequality
How does social position translate into differential health outcomes in communities undergoing rapid socio-economic transition? The Omo Valley Research Project is building a biosocial dataset across the Hamar, Kara, Kwegu, and Nyangatom, linking demographic and economic profiles to anthropometric, cardiometabolic, and functional health measures. Working with Ethiopian epidemiologists and virologists, we are adding biomarkers of stress and immune function to test how market integration, network position, and gendered institutions shape physiological well-being.