The relationship between ethnic heterogeneity and economic growth is complex. Empirical research working with cross-country data finds a negative, or statistically insignificant, relationship. However, analysis at the city level finds a positive effect of diversity on wages and productivity. Generally there is a trade-off between the economic benefits of diversity and the costs of heterogeneity. Using cells of fixed size, we find that the relationship between diversity and growth is positive for small geographical areas. In the case of Africa, we argue that the explanation is the increase in trade at the boundaries between ethnic groups due to ethnic specialization.

Previous research has interpreted the correlation between per capita income and civil war as evidence that poverty is a main determinant of conflict. In this paper, we find that the relationship between poverty and civil war is spurious and is accounted for by historical phenomena that jointly determine income evolution and conflict. In particular, the statistical association between poverty and civil wars disappears once we include country fixed effects. Also, using cross‐section data for 1960 to 2000, we find that once historical variables like European settler mortality rates and the population density in 1500 are included in civil war regressions, poverty does not have an effect on civil wars. These results are confirmed using longer time series from 1825 to 2000.

The World Health Organization estimates that 300 million clinical cases of malaria occur annually and observed that during the 80s and part of the 90s its incidence increased. In this paper, we explore the influence of refugees from civil wars on the incidence of malaria in the refugee-receiving countries. Using civil wars as an instrumental variable, we show that for each 1,000 refugees there are between 2,000 and 2,700 cases of malaria in the refugee-receiving country. On average 13% of the cases of malaria reported by the WHO are caused by forced migration as a consequence of civil wars.