Social complexity is not strongly predictive of indiscriminate killing of wartime enemies in a cross-cultural sample

The origins and correlates of war are historically contentious in anthropology, with researchers divided over its relationship to the development of agriculture, sedentism, and centralized states. Although this research tends not to focus on norms of wartime conduct, its arguments can be extended to how the levels and forms of violence directed at enemies vary with social complexity. For this study, variables on social complexity and warfare were coded from ethnographic and historical sources into a cross-cultural data set of 73 societies. The likelihood of different individuals who were enemies of the focal society being targeted or killed during war was tested for relationships with measures of social complexity and violent conquest of external populations. The results of the analyses provided little to no evidence for increased or decreased indiscriminate violence with social complexity (as measured by population size, governance levels, and centralization), or for a strong relationship with formal military structures and political/territorial expansion. A multidisciplinary literature review of how wartime violence relates to social structures is also presented. Interpretations, limitations, and future directions are discussed in the context of comparative cultural databases and their applications to cultural evolution research.