This research explores the persistent effect of the prehistoric exodus of Homo sapiens from Africa on the composition of human traits within human populations and, thus, on comparative economic development across societies from the dawn of civilization to the contemporary era.

This research has advanced the hypothesis and empirically established that migratory distances from the cradle of mankind in East Africa to the indigenous settlements of the ancestral populations of nations or ethnic groups, and its negative impact on their levels of diversity generated a persistent hump-shaped influence on development outcomes, reflecting the fundamental trade-off between the beneficial and detrimental effects of diversity on productivity at the societal level.

Although diversity diminishes interpersonal trust, cooperation, and economic coordination, adversely affecting the productivity of society, complementarity and cross fertilization across diverse productive traits stimulates innovations and gains from specialization, thus contributing to society's economic performance. In the presence of diminishing marginal returns to diversity and homogeneity, the aggregate productivity of ethnic groups, countries, or regions that are characterized by intermediate levels of diversity is therefore expected to be higher than that associated with excessively homogenous or heterogeneous societies.

Consistent with the fundamental building blocks of this hypothesis, empirical evidence indicates that interpersonal population diversity has:

  • An adverse effect on social cohesion, as reflected by greater ethnolinguistic fractionalization, lower trust,  and great prevalence of ethnic conflicts. 

  • A beneficial effect on innovative activity,  occupational heterogeneity, and gains from specialization, and cross-fertilization in classrooms and decision making of board of directors.

Moreover, population diversity has shaped the nature of both precolonial and contemporary political institutions. In particular, although diversity triggered the development of institutions for mitigating the adverse influence of diversity on social cohesion, the contribution of diversity to economic inequality and class stratification ultimately led to the formation and persistence of extractive and autocratic institutions.



Impact of population diversity on: urbanization 1500 (bottom right); population density (bottom left); income per capita 2000 (up right); light intensity across ethnic group (top right) 


Ashraf, Q., & Galor, O. (2013). The 'Out of Africa' Hypothesis, Human Genetic Diversity, and Comparative Economic Development. American Economic Review, 103(1), 1-46.

This research advances and empirically establishes the hypothesis that, in the course of the prehistoric exodus of Homo sapiens out of Africa, variation in migratory distance to various settlements across the globe affected genetic diversity and has had a persistent hump-shaped effect on comparative economic development, reflecting the trade-off between the beneficial and the detrimental effects of diversity on productivity. While the low diversity of Native American populations and the high diversity of African populations have been detrimental for the development of these regions, the intermediate levels of diversity associated with European and Asian populations have been conducive for development.




Ashraf, Q., & Galor, O. (2013). Genetic Diversity and the Origins of Cultural Fragmentation. American Economic Review, 103(3), 528-33.

The origin of the uneven distribution of ethnic and cultural fragmentation across countries has been underexplored, despite the importance attributed to the effects of diversity on the stability and prosperity of nations. Building on the role of deeply-rooted biogeographical forces in comparative development, this research empirically demonstrates that genetic diversity, predominantly determined during the prehistoric "out of Africa" migration of humans, is an underlying cause of various existing manifestations of ethnolinguistic heterogeneity. Further research may revolutionize our understanding of how economic development and the composition of human capital across the globe are affected by these deeply-rooted factors.



Arbatlı, C. E., Ashraf, Q. H., Galor, O., & Klemp, M. (2020). Diversity and conflict. Econometrica, 88(2), 727-797.

This research advances the hypothesis and establishes empirically that interpersonal population diversity, rather than fractionalization or polarization across ethnic groups, has been pivotal to the emergence, prevalence, recurrence, and severity of intrasocietal conflicts. Exploiting an exogenous source of variations in population diversity across nations and ethnic groups, as determined predominantly during the exodus of humans from Africa tens of thousands of years ago, the study demonstrates that population diversity, and its impact on the degree of diversity within ethnic groups, has contributed significantly to the risk and intensity of historical and contemporary civil conflicts. The findings arguably reflect the contribution of population diversity to the non‐cohesiveness of society, as reflected partly in the prevalence of mistrust, the divergence in preferences for public goods and redistributive policies, and the degree of fractionalization and polarization across ethnic, linguistic, and religious groups.



Ashraf, Q. H., & Galor, O. (2018). The Macrogenoeconomics of Comparative Development. Journal of Economic Literature, 56(3), 1119-55.

The importance of evolutionary forces for comparative economic performance across societies has been the focus of a vibrant literature, highlighting the roles played by the Neolithic Revolution as well as the prehistoric "out of Africa" migration of anatomically modern humans in generating worldwide variations in the composition of human traits. This essay provides an overview of the literature on the macrogenoeconomics of comparative development, underscoring the significance of evolutionary processes and human population diversity in generating differential paths of economic development across societies.


Open Book

Ashraf, Quamrul, Oded Galor, and Marc Klemp, "The Out of Africa Hypothesis of Comparative Economic Development: Common Misconceptions" (December 2018)

Ashraf, Quamrul, Oded Galor, and Marc Klemp,  "Interpersonal Diversity and Socioeconomic Disparities Across Populations: A Reply to Rosenberg and Kang" (December 2018

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