A social biogeography of Homicide: Multilevel and sequential canonical examinations of intragroup Unlawful Killings

A considerable number of publications have examined the effect of various geographical, life history, social, economic and political factors on homicide. However, few studies were interested in examining the effect of these forces in an integrated social biogeography of homicide. This study collected data for 172 nation-states from various publications and databases. Standardized Studentized residuals were extracted from a multilevel model examining the effects of geographical adjacency upon homicide rates. A general linear model was used, with the residuals, to observe the effects of physical, community, social, cultural, and cognitive ecology upon homicide. Two sequential canonical analyses (SEQCA) were conducted to determine the mediating effects among the ecological indicators with respect to homicide. In the SEQCA, we hypothesized physical ecology would lead to communal ecology, in turn leading to social ecology, subsequently leading to cognitive ecology, and ultimately to homicide. A parsimony test concluded that economic growth and inequality fully mediated the relationship between cognitive ecology and homicide residuals. Similarly, the effects of life history upon homicide were fully mediated by social ecology. This study suggests several social ecology factors appear to directly affect homicide; however, other aspects of ecology indirectly affected homicide through influences on social ecology. The effect of indicators of social ecology such as income inequality and the operational sex ratio indicate competition for resources is a significant force generating differences in homicide rates across populations. In conclusion, a suite of evolutionary pressures seems to influence homicide rates, but mainly in a sequential nature rather than simultaneously.