I work on two strands of research. First, I investigate the rural economic geography and its implications for human and ecological well-being in developing economies with particular focuses on agriculture, economies of density, market transaction costs, natural resources, trade, and tropical forests. Second, I study conflicts involving violent extremist organizations from spatial, historical, and behavioral perspectives.
“Human and Nature: Economies of Density and Conservation in the Amazon Rainforest”
with Yoshito Takasaki and Mari Tanaka [Updated often] Job Market Paper
Conserving tropical forests impacts the standard of living of local populations. Moreover, human adaptation through sectoral or spatial reallocation of economic activity may undermine conservation policy goals. To derive policies that balance human and ecological well-being, this paper estimates a multi-sector spatial model that formalizes human-nature interactions using high-resolution georeferenced data from roadless river basins in the Peruvian Amazon. Identification comes from plausibly exogenous variation in the structure of river networks. We find that the agglomeration externality in agricultural production outweighs dispersion forces in access to land, implying that higher concentration leads to higher productivity with less deforestation per farmer. We also find a strong congestion externality with spatial spillovers in natural resource extraction. The estimated agglomeration externality, primarily driven by economies of scale in transport technology and agricultural intensification, generates large welfare and forest cover gains but leads to natural resource depletion through general equilibrium effects. Counterfactuals demonstrate that combining well-targeted place-based protection policies and transport infrastructure can simultaneously achieve higher welfare, lower deforestation, and less natural resource depletion.
“The Golden City on the Edge: Economic Geography and Jihad over Centuries”
with Masahiro Kubo [arXiv] Hayami Award 2022
This paper uncovers the evolution of cities and Islamist insurgencies, so called jihad, in the process of the reversal of fortune over the centuries. In West Africa, water access in ancient periods predicts the locations of the core cities of inland trade routes—the trans-Saharan caravan routes—founded up to the 1800s, when historical Islamic states played significant economic roles before European colonization. In contrast, ancient water access does not have a persistent influence on contemporary city formation and economic activities. After European colonization and the invention of modern trading technologies, along with the constant shrinking of water sources, landlocked pre-colonial core cities contracted or became extinct. Employing an instrumental variable strategy, we show that these deserted locations have today been replaced by battlefields for jihadist organizations. We argue that the power relations between Islamic states and the European military during the 19th century colonial era shaped the persistence of jihadist ideology as a legacy of colonization. Investigations into religious ideology related to jihadism, using individual-level surveys from Muslims, support this mechanism. Moreover, the concentration of jihadist violence in “past-core-and-present-periphery” areas in West Africa is consistent with a global-scale phenomenon.
“Refugee Inflows, Surplus Farm Labor, and Crop Marketization in Rural Africa”
Journal of Development Economics, Volume 155, March 2022, 102805 [working paper ver.]
This paper sheds light on the structure of factor and output market frictions to investigate long-term effects of refugee inflows on host farmers. Combining a canonical agricultural household model, the natural experimental setting of mass refugee inflows into Tanzania in the early 1990s, and longitudinal panel data from the host economy, I show that refugee inflows cause market-specific gains and losses. Refugee inflows tighten the off-farm labor market participation constraint, implying an increase in surplus farm labor and labor market inefficiency. On the other hand, I observe a positive impact on the transition from subsistence to crop marketization. This transition is revealed to be primarily due to a reduction in fixed transaction costs around refugee camps, not due to an increase in consumption demand by refugees. While the overall impact on agricultural labor productivity is negative, the “surplus farm labor effect” and the “crop marketization effect” act in opposite directions.
Works in Progress
“Caste Segregation and Spatial Misallocation in
with Kazuki Motohashi and Mike Neubauer
“De-Radicalization and Reintegration from
Violent Islamic Extremism”
with Robert Blair, Jun Goto, and Yosuke Nagai
“The Economics of Subsistence in Africa”
S4 Graduate Student Paper Prize, the 2nd place, 2020
Publications in Japanese
“Entrepreneurship, Informality, and Preference Heterogeneity within Small and Micro-Businesses in India.” The Economic Review, 69.3 (2018): 242-275.” with Jun Goto, Hironori Ishizaki, Takashi Kurosaki, and Yasuyuki Sawada
ECON2020 Computing for Economists (Syllabus), Instructor (2020, 2021, 2023)
Teaching Award 2021 (Evaluations)
Introduction to Python
Software Engineering for Social Scientists
Nonlinear-Equation Solving & Numerical Optimization
Numerical Differentiation & Integration
The University of Tokyo
Development Economics: Macroeconomic Approach, TA for Prof. Kenichi Ueda, 2016
Natural Resource and Environmental Economics, TA for Prof. Yoshito Takasaki, 2015
Case Study: Financial Development and Inequality, TA for Prof. Kenichi Ueda, 2015