Current research

How much disease is caused by environmental hazards that existing observation systems fail to detect? One such hazard is transient stagnant water, which can transmit enteric pathogens and provide mosquito breeding habitat but remains largely invisible to conventional satellite monitoring. Here we develop a 90-m hydrological model to reconstruct stagnant water across Tanzania, validate it against independent wetland and soil-moisture observations, and estimate its health effects using nationally representative child-health data. We find that moving from zero to 3% of surrounding land under stagnant water increases two-week diarrhoea prevalence by 4.8 percentage points (95% CI, 1.5–8.2), equivalent to 45% of mean prevalence, and reduces haemoglobin by 2.41 g/L (95% CI, 0.3–4.6). The diarrhoeal response is substantially larger among households relying on surface drinking water, whereas haemoglobin reductions are concentrated in malaria-suitable areas, consistent with complementary enteric and vector-borne pathways. We estimate that stagnant water accounts for 11.3% (95% CI, 4.3–18.7%) of under-five diarrhoea in Tanzania, corresponding to approximately 445 child deaths annually from the diarrhoeal pathway alone. In a policy simulation, targeting a one-percentage-point expansion in national oral-rehydration coverage towards high-exposure areas would avert an estimated 139 under-five deaths annually, twice as many as untargeted allocation. Because the model inputs are globally available, this framework can be extended beyond Tanzania to map previously unobserved stagnant-water exposure and improve the targeting of health interventions.

How do households self-insure against climate risk when the underlying distribution is unobserved? I derive climate contrast from a recency-weighted reference-point framework, distinguishing the ordering of recent shocks from their overall variability. In Tanzania, higher contrast is associated with greater assessed shock exposure, more emergency saving, stronger asset buffers, and better food security. The saving relationship extends across 29 low- and middle-income countries. Yet contrast has little predictive content for subsequent drought and climate variability, while conventional variability measures do. Households thus appear to respond to a different climate signal from the one that forecasts these risks.

This paper examines the cultural roots of parental investment in children's human capital, focusing on two predominant kinship systems in developing countries: matrilineal and patrilineal descent. Using novel survey data from Tanzania, we measure parental investments in children's learning, including the time and attention parents devote to their education. Employing a fuzzy spatial regression discontinuity design, we find that matrilineal parents invest less in their children's human capital. For example, they are less likely to check their children's homework or discuss their academic performance with teachers. Children from matrilineal backgrounds also exhibit lower cognitive skills, as measured by standardized numeracy and literacy tests. Our analysis suggests that spousal conflict and cooperation, family instability, and labor market conditions may help explain these differences. Finally, we examine a nation-building reform intended to weaken ethnic divisions and traditional norms, finding that it did not effectively counteract the influence of traditional kinship systems.

We examine the mechanisms through which the transatlantic slave trade eroded trust in Africa by creating incentives for kidnapping and social betrayal. Exploiting variation in slave prices and transaction costs, we show that the negative relationship between slave trade exposure and contemporary trust is concentrated where opportunistic enslavement was more profitable, owing to higher slave prices and lower transaction costs. Using child slave exports as a proxy for kidnapping-intensive procurement, we find that this form of enslavement accounts for much of the slave trade–mistrust relationship. Oral histories illustrate how mistrust was transmitted across generations, highlighting the cultural channel of persistence.