Age structure, socio-political institutions, and national homicide rates

Both the high propensity of young people to commit homicide and the social and financial problems faced by large cohorts during their youth suggest that increases in the proportion of the population at ages 15-29 contribute to higher national homicide rates. Although confirmed by time-series studies of the United States, the expected macro-level relationship does not emerge in cross-national studies of other high-income nations. We argue that the diverse results stem from the varied development of national institutions for collective social protection across high-income nations which mitigate the impact of changes in the percentage of young people on homicide. Results from pooled cross-sectional time-series analyses for eighteen countries and 36 years support the hypothesis: national context, as measured by a scale of collectivism, reduces the otherwise positive effects of the percentage youth on homicide. The findings suggest the need for theories to integrate demographic, political, and criminological perspectives in understanding social diversity among otherwise economically similar high-income democratic nations.