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This paper documents a novel but salient empirical fact – namely, that the risk of intrastate conflict faced by societies in the modern world partly reflects the long shadow of prehistory. Specifically, exploiting variations across contemporary national populations, we establish that genetic diversity, overwhelmingly determined during the course of the prehistoric demic diffusion of humans “out of Africa” to the rest of the globe, has contributed significantly to the temporal frequency, incidence, and onset of both overall and ethnic civil conflict events over the last half-century, accounting for the potentially confounding influence of a large set of geographical characteristics, institutional factors, measures of ethnolinguistic fragmentation, and outcomes of economic development. Our analysis additionally demonstrates that genetic diversity possesses significant explanatory power for not only the intensity of social unrest but also the incidence of intragroup factional conflicts in contemporary national populations. Importantly, the reduced-form causal influence of genetic diversity on the risk of intrastate conflict in the modern era remains qualitatively unchanged under a comprehensive range of robustness checks.
Our key finding in this paper arguably reflects the contribution of genetic diversity to the ethnolinguistic fragmentation of a national population, the adverse influence of genetic diversity on social capital, the contribution of genetic diversity to heterogeneity in preferences for public goods and redistributive policies, and possibly, the potential impact of genetic diversity on economic inequality within a society.