We test the longstanding hypothesis that ethnic groups organized around “segmentary lineages” are more prone to conflict. Ethnographic accounts suggest that in such societies, which are characterized by strong allegiances to distant relatives, individuals are obligated to come to the aid of fellow lineage members when they become involved in conflicts. As a consequence, small disagreements often escalate into larger‐scale conflicts involving many individuals. We test for a link between segmentary lineage organization and conflict across ethnic groups in sub‐Saharan Africa. Using a number of estimation strategies, including a regression discontinuity design at ethnic boundaries, we find that segmentary lineage societies experience more conflicts, and particularly ones that are retaliatory, long in duration, and large in scale.

We study the effects of European immigration to the U.S. during the Age of Mass Migration (1850–1920) on economic prosperity. Exploiting cross-county variation in immigration that arises from the interaction of fluctuations in aggregate immigrant flows and of the gradual expansion of the railway network, we find that counties with more historical immigration have higher income, less poverty, less unemployment, higher rates of urbanization, and greater educational attainment today. The long-run effects seem to capture the persistence of short-run benefits, including greater industrialization, increased agricultural productivity, and more innovation.

We document an important consequence of bride price, a payment made by the groom to the bride’s family at marriage. Revisiting Indonesia’s school construction program, we find that among ethnic groups without the custom, it had no effect on girls’ schooling. Among ethnic groups with the custom, it had large positive effects. We show (theoretically and empirically) that this is because a daughter’s education, by increasing the amount of money parents receive at marriage, generates an additional incentive for parents to educate their daughters. We replicate these findings in Zambia, a country that had a similar large-scale school construction program.