The Young and the Restless: Population Age Structure and Civil War

T hree months after the attacks of September 11, 2001, the New York Times asked, “Is the Devil in the Demographics?” (Sciolino, 2001). The article examined the vulnerability of large cohorts of unemployed youth to extremist ideology and political recruitment, and speculated about the hazards created by future youth cohorts in the Middle East. In the post-9/11 era, however, there has been very little academic research on the relationship between youthful age structure and warfare (three notable exceptions: Urdal, 2002; Hammel & Smith, 2002; Cincotta et al., 2003). Literature on civil war and insurgency has instead highlighted the role of other causal factors such as the presence of valuable resources, the degree of ethnic fractionalization, and type of political regime, while downplaying the importance of population age structure (see, e.g., Collier & Hoeffler, 2001; Fearon & Laitin, 2003; Elbadawi & Sambanis, 2002). While these factors likely play an important role in the onset of civil war,1 the importance of youthful age structure—particularly in insurgency-based civil wars2—should not be ignored. The relationship between large youth cohorts and civil war appears to have held throughout history. For example, Herbert Moller (1968) suggests that wars in pre-modern and present-day Europe, including the rise of the Nazi party in Germany, corresponded with surges in the proportion of young men in the population. Yale historian Paul Kennedy (1993) argues that revolutions occur more often in countries with large populations of “energetic, frustrated, young men.”3 Even after controlling for the fact that more youthful countries are less developed and have more vulnerable political regimes, my research finds that a large difference in the number of young adults compared to the number of older adults—“relative cohort size”—can help predict civil war, particularly insurgent-based civil wars.