Neoliberals and their neorealist critics have debated the relative importance of two main obstacles to international cooperation—problems of cheating and enforcement and problems of relative gains. By contrast, I argue that problems of international cooperation have a common strategic...

We examine a public goods game in 83 communities in northern Liberia. Women contributed substantially more to a small-scale development project when playing with other women than in mixed-gender groups, where they contributed at about the same levels as men. We try to explain this composition...

Can brief, foreign-funded efforts to build local institutions have positive effects on local patterns of governance, cooperation, and well-being? Prior research suggests that such small-scale, externally driven interventions are unlikely to substantially alter patterns of social interaction in a...

This brief paper summarizes results from an analysis of the World Development Report (WDR) homicide dataset (February 24, 2010), which is based primarily on estimates from the United Nations Office against Drugs and Crime (UNODC), with some changes or additions from national sources and the...

Social evolution is one of the most rapidly developing areas in evolutionary biology. A main theme is the emergence of cooperation among organisms, including the factors that impede cooperation. Although animal societies seem to have no formal institutions, such as courts or legislatures, we...