# Research

Published or Forthcoming

• The Origins of the Division of Labor in Pre-Industrial Times, joint with Emilio Depetris-Chauvin. Journal of Economic Growth, 2020, Vol. 25(3), 297-340. (WP) (Data)
Abstract
This research explores the historical roots of the division of labor in pre-modern societies. Exploiting a variety of identification strategies and a novel ethnic level dataset combining geocoded ethnographic, linguistic and genetic data, it shows that higher levels of intra-ethnic diversity were conducive to economic specialization in the pre-modern era. The findings are robust to a host of geographical, institutional, cultural and historical confounders, and suggest that variation in intra-ethnic diversity is a key predictor of the division of labor in pre-modern times.
• Linguistic Traits and Human Capital Formation, joint with Oded Galor and Assaf Sarid. AEA Papers and Proceedings, 2020. 110: 309-13. (WP)
Abstract
This research establishes the influence of linguistic traits on human behavior. Exploiting variations in the languages spoken by children of migrants with identical ancestral countries of origin, the analysis indicates that the presence of periphrastic future tense, and its association with long-term orientation has a significant positive impact on educational attainment, whereas the presence of sex-based grammatical gender, and its association with gender bias, has a significant adverse impact on female educational attainment.
• Distance to the Pre-industrial Technological Frontier and Economic Development, Journal of Economic Growth, 2018, Vol. 23(2), 175-221. (WP) (Data) (HMI Project) (Ungated Paper) (Ungated Replication Files) (slides),
Abstract
This research explores the effects of distance to the pre-industrial technological frontiers on comparative economic development in the course of human history. It establishes theoretically and empirically that distance to the frontier had a persistent non-monotonic effect on a country’s pre-industrial economic development. In particular, advancing a novel measure of the travel time to the technological frontiers, the analysis establishes a robust persistent U-shaped relation between distance to the frontier and pre-industrial economic development across countries. Moreover, it demonstrates that countries, which throughout the last two millennia were relatively more distant from these frontiers, have higher contemporary levels of innovation and entrepreneurial activity, suggesting that distance from the frontier may have fostered the emergence of a culture conducive to innovation, knowledge creation, and entrepreneurship.
• Culture, Diffusion, and Economic Development: The Problem of Observational Equivalence, joint with Ani Harutyunyan. Economics Letters, 2017, Vol. 158(C):94-100.
Abstract
This research explores the direct and barrier effects of culture on economic development. It shows both theoretically and empirically that whenever the technological frontier is at the top or bottom of the world distribution of a cultural value, there exists an observational equivalence between absolute cultural distances and cultural distances relative to the frontier, preventing the identification of its direct and barrier effects. Since the technological frontier usually has the “right” cultural values for development, it tends to be in the extremes of the distribution of cultural traits, generating observational equivalence and confounding the analysis. These results highlight the difficulty of disentangling the direct and barrier effects of culture. The empirical analysis finds suggestive evidence for direct effects of individualism and conformity with hierarchy, and barrier effects of hedonism.
• The Agricultural Origins of Time Preference, joint with Oded Galor. The American Economic Review, 2016, 106(10):3064–3103. (Working Paper) (CSI Project)(Slides)
Abstract
This research explores the origins of the distribution of time preference across regions. Exploiting a natural experiment associated with the expansion of suitable crops for cultivation in the course of the Columbian Exchange, the research establishes that pre-industrial agro-climatic characteristics that were conducive to higher return to agricultural investment, triggered selection, adaptation and learning processes that have had a persistent positive effect on the prevalence of long-term orientation in the contemporary era. Furthermore, the research establishes that these agro-climatic characteristics have had a culturally-embodied impact on economic behavior such as technological adoption, education, saving, and smoking.

Coverage
• Optimal consumption under uncertainty, liquidity constraints, and bounded rationality, Journal of Economic Dynamics and Control, 2014, Vol. 39: 237-254 (Working paper) (code)
Abstract
I study how boundedly rational agents can learn a “good” solution to an infinite horizon optimal consumption problem under uncertainty and liquidity constraints. Using an empirically plausible theory of learning I propose a class of adaptive learning algorithms that agents might use to choose a consumption rule. I show that the algorithm always has a globally asymptotically stable consumption rule, which is optimal. Additionally, I present extensions of the model to finite horizon settings, where agents have finite lives and life-cycle income patterns. This provides a simple and parsimonious model of consumption for large agent based models.
• Adaptive Consumption Behavior, joint with Peter Howitt. Journal of Economic Dynamics and Control, 2014, Vol. 39: 37-61 (NBER working paper) (appendix)
Abstract
In this paper we propose and study a theory of adaptive consumption behavior under income uncertainty and liquidity constraints. We assume that consumption is governed by a linear function of wealth, whose coefficients are revised each period by a procedure that places few informational or computational demands on the consumer. We show that under a variety of settings the procedure converges quickly to a set of coefficients with low welfare cost relative to a fully optimal nonlinear consumption function.
• Isolation and Development, joint with Oded Galor and Quamrul Ashraf. Journal of the European Economic Association, April/May 2010, Vol. 8, No. 2-3: 401-412. (Data)
Abstract
This paper exploits cross-country variation in the degree of geographical isolation, prior to the advent of sea-faring and airborne transportation technologies, to examine its impact on the course of economic development across the globe. The empirical investigation establishes that prehistoric geographical isolation has generated a persistent beneficial eﬀect on the process of development and contributed to the contemporary variation in the standard of living across countries.
• Optimización y Dinámica, joint with Sergio Monsalve, in Sergio Monsalve (ed.) “Matemáticas básicas para economistas. (Con notas históricas y contextos económicos), No. 3., Editorial Universidad Nacional de Colombia, Bogotá, 2010
• Two-sided Matching Models, joint with Marilda Sotomayor, in R.A. Meyers (ed.) “Encyclopedia of Complexity and Systems Science”, Springer-Verlag, New York 2008. Reprinted in Computational Complexity, 2012
• Comportamiento Asintótico y Selección de Equilibrios en Juegos Evolutivos, Editorial Universidad Externado de Colombia, Bogotá, 2006
• Equilibrios Múltiples y Tasa Natural de Interés, Academia Colombiana de Ciencias Económicas, Bogotá, 2005
Recent Working Papers

• Millet, Rice, and Isolation: Origins and Persistence of the World’s Most Enduring Mega-State, joint with James Kung, Louis Putterman, and Shuang Shi
Abstract
We propose and empirically test a theory for the endogenous formation and persistence of large states, using China as an example. We suggest that the relative timing of the emergence of agricultural societies and their distance to each other set off a race between autochthonous state-building projects and the expansion of neighboring (proto-)states. Using a novel dataset on the Chinese state’s historical presence, the timing of agricultural adoption, social complexity, climate, and geography across $1\times1$ degree grid cells in East Asia, we provide empirical support for this hypothesis. Specifically, we find that on average, cells that adopted agriculture earlier or were close to the earliest archaic state in East Asia (Erlitou) remained longer under Sinitic control. In contrast, earlier adoption of agriculture decreased the persistent control of the Chinese state in cells farther than 2.8 weeks of travel from Erlitou.
• Expanding the Measurement of Culture with a Sample of Two Billion Humans, joint with Nick Obradovich, Ignacio Martín, Ignacio Ortuño-Ortín, Edmond Awad, Manuél Cebrián, Rubén Cuevas, Klaus Desmet, Iyad Rahwan and Ángel Cuevas.
Abstract
Culture has played a pivotal role in human evolution. Yet, the ability of social scientists to study culture is limited by the currently available measurement instruments. Scholars of culture must regularly choose between scalable but sparse survey-based methods or restricted but rich ethnographic methods. Here, we demonstrate that massive online social networks can advance the study of human culture by providing quantitative, scalable, and high-resolution measurement of behaviorally revealed cultural values and preferences. We employ publicly available data across nearly 60,000 topic dimensions drawn from two billion Facebook users across 225 countries and territories. We first validate that cultural distances calculated from this measurement instrument correspond to traditional survey-based and objective measures of cross-national cultural differences. We then demonstrate that this expanded measure enables rich insight into the cultural landscape globally at previously impossible resolution. We analyze the importance of national borders in shaping culture, explore unique cultural markers that identify subnational population groups, and compare subnational divisiveness to gender divisiveness across countries. The global collection of massive data on human behavior provides a high-dimensional complement to traditional cultural metrics. Further, the granularity of the measure presents enormous promise to advance scholars’ understanding of additional fundamental questions in the social sciences. The measure enables detailed investigation into the geopolitical stability of countries, social cleavages within both small and large-scale human groups, the integration of migrant populations, and the disaffection of certain population groups from the political process, among myriad other potential future applications.
• Borderline Disorder: (De facto) Historical Ethnic Borders and Contemporary Conflict in Africa, joint with Emilio Depetris-Chauvin
Abstract
We explore the effect of historical ethnic borders on contemporary non-civil conflict in Africa. Exploiting variations across artificial regions (i.e., grids of $50\times50$km) within an ethnicity’s historical homeland, we document that both the intensive and extensive margins of contemporary conflict are concentrated close to historical ethnic borders. Following a theory-based instrumental variable approach, which generates a plausibly exogenous ethno-spatial partition of Africa, we find that grid cells with historical ethnic borders have 27 percentage points higher probability of conflict and 7.9 percentage points higher probability of being the initial location of a conflict. We uncover several key underlying mechanisms: competition for agricultural land, population pressure, cultural similarity and weak property rights.
• Geographical Roots of the Coevolution of Cultural and Linguistic Traits, joint with Oded Galor and Assaf Sarid
Abstract
This research explores the geographical origins of the coevolution of cultural and linguistic traits in the course of human history, relating the geographical roots of long-term orientation to the structure of the future tense, the agricultural determinants of gender bias to the presence of sex-based grammatical gender, and the ecological origins of hierarchical orientation to the existence of politeness distinctions. The study advances the hypothesis and establishes empirically that: (i) geographical characteristics that were conducive to higher natural return to agricultural investment contributed to the existing cross-language variations in the structure of the future tense, (ii) the agricultural determinants of gender gap in agricultural productivity fostered the existence of sex-based grammatical gender, and (iii) the ecological origins of hierarchical societies triggered the emergence of politeness distinctions.

Coverage
• Geographical Origins of Language Structures, joint with Oded Galor and Assaf Sarid
Abstract
This research explores the geographical origins of the coevolution of cultural and linguistic traits in the course of human history, relating the geographical roots of long-term orientation to the structure of the future tense, the agricultural determinants of gender bias to the presence of sex-based grammatical gender, and the ecological origins of hierarchical orientation to the existence of politeness distinctions. The study advances the hypothesis and establishes empirically that: (i) variations in geographical characteristics that were conducive to higher natural return to agricultural investment contributed to the existing cross-language variations in the structure of the future tense, (ii) the agricultural determinants of gender gap in agricultural productivity fostered the existence of sex-based grammatical gender, and (iii) the ecological origins of hierarchical societies triggered the emergence of politeness distinctions.
• Geographical Origins and Economic Consequences of Language Structures, joint with Oded Galor and Assaf Sarid
Abstract
This research explores the economic causes and consequences of language structures. It advances the hypothesis and establishes empirically that variations in pre-industrial geographical characteristics that were conducive to higher returns to agricultural investment, gender gaps in agricultural productivity, and the emergence of hierarchical societies, are at the root of existing cross-language variations in the structure of the future tense and the presence of grammatical gender and politeness distinctions. Moreover, the research suggests that while language structures have largely reflected past human experience and ancestral cultural traits, they have independently affected human behavior and economic outcomes.
• The Origins and Long-Run Consequences of the Division of Labor, joint with Emilio Depetris-Chauvin
Abstract
This research explores the historical roots and persistent effects of the division of labor in pre-modern societies. Exploiting a novel ethnic-level dataset, which combines geocoded ethnographic, linguistic and genetic data, it advances the hypothesis and establishes empirically that population diversity had a positive effect on the division of labor, which translated into persistent differences in economic development. Specifically, it establishes that pre-modern economic specialization was conducive to pre-modern statehood, urbanization and social hierarchy. Moreover, it demonstrates that higher levels of pre-modern economic specialization are associated with greater skill-biased occupational heterogeneity, economic complexity and economic development in the contemporary era.
• Population Diversity, Division of Labor and the Emergence of Trade and State, joint with Emilio Depetris-Chauvin
Abstract
This research explores the emergence and prevalence of economic specialization and trade in pre-modern societies. It advances the hypothesis, and establishes empirically that population diversity had a positive causal effect on economic specialization and trade. Based on a novel ethnic level dataset combining geocoded ethnographic and genetic data, this research exploits the exogenous variation in population diversity generated by the “Out-of-Africa” migration of anatomically modern humans to causally establish the positive effect of population diversity on economic specialization and the emergence of trade-related institutions, which, in turn, facilitated the historical formation of states. Additionally, it provides suggestive evidence that regions historically inhabited by pre-modern societies with high levels of economic specialization have a larger occupational heterogeneity and are more developed today.
• Land Productivity and Economic Development: Caloric Suitability vs. Agricultural Suitability, joint with Oded Galor
Abstract
This paper establishes that the Caloric Suitability Index (CSI) dominates the commonly used measure of agricultural suitability in the examination of the effect of land productivity on comparative economic development. The analysis demonstrates that the agricultural suitability index does not capture the large variation in the potential caloric yield across equally suitable land, reflecting the fact that land suitable for agriculture is not necessarily suitable for the most caloric-intensive crops. Hence, in light of the instrumental role played by caloric yield in sustaining and supporting population growth, and given importance of pre-industrial population density for the subsequent course of economic development, the Caloric Suitability Index dominates the conventional measure in capturing the effect of land productivity on pre-colonial population density and the subsequent course of economic development.
• Culture, Diffusion, and Economic Development, joint with Ani Harutyunyan
Abstract
This research explores the effects of culture on technological diffusion and economic development. It shows that culture’s direct effects on development and barrier effects to technological diffusion are, in general, observationally equivalent. In particular, using a large set of measures of cultural values, it establishes empirically that pairwise differences in contemporary development are associated with pairwise cultural differences relative to the technological frontier, only in cases where observational equivalence holds. Additionally, it establishes that differences in cultural traits that are correlated with genetic and linguistic distances are statistically and economically significantly correlated with differences in economic development. These results highlight the difficulty of disentangling the direct and barrier effects of culture, while lending credence to the idea that common ancestry generates persistence and plays a central role in economic development.
• The Voyage of Homo-œconomicus: some economic measures of distance
Research In Progress