The article tests theories that may explain why warfare frequency varies from society to society. The focus is on ecological problems, particularly different kinds of resource scarcity, but social and psychological theories are also tested with both bivariate and multivariate analyses. Because unpredictable disasters are such a strong predictor in nonstate societies, the authors theorize that war may mostly be caused by a fear of nature.

This paper reviews the results of the author's cross-cultural studies of war and aggression and their implications for prehistory.

This study explores several correlates of interpersonal violence. Multiple regression analysis suggests that socialization for aggression in boys in late childhood is the strongest predictor of higher rates of homicide and assault. Path analysis suggests that socialization for aggression is a consequence, not a cause, of war.

The present study attempts to replicate the Ember, Ember, and Russett (1992) worldwide finding that fighting rarely occurs between democracies in a sample of eastern African societies. Following the earlier study, the authors considered internal warfare to be an analog of international warfare and measures of political participation analogous to democracy. The researchers also explore if there is an association between political participation and committing atrocities. Contrary to past findings, internal warfare was not predicted by the same set of variables as the 1992 study, but there is an inverse relationship between committing atrocities and political participation. However, when additional variables were added, internal warfare was significantly predicted by less political participation.

This article examines resource problems and warfare in a sample of societies from eastern Africa. The frequency and predictability of resource problems are examined, as are two other dimensions of warfare: resource-taking and commission of atrocities. Differences between state and nonstate societies, as well as pacified and non-pacified societies, are also examined and shown to affect associations between resource and warfare variables.

This article presents two evolutionary models that may explain relationships between war and socialization of children: the "environmentally contingent reproductive strategy" (ECRS) model put forward by Draper and Harpending (1982), and a model put forward by Carol and Melvin Ember. Results do not provide support for the hypotheses involving father-infant sleeping proximity derived from the ECRS model. The authors also find some inconsistencies with their own model.

This paper supports Beatrice B. Whiting's (1965) sex-identity conflict hypothesis which suggests a relationship between males' early identification with their mothers and male violence. Authors find that, in addition to socialization aggression, frequency of homicide/assault is significantly related to father-infant sleeping distance, particularly when residence is not matrilocal and/or warfare is more than occasional.

This article tests the effects of variables associated with political participation on the frequency of internal warfare. Findings suggest support for the hypothesis that democracies rarely fight each other.

This article tests various explainations for corporal punishment of children, including social complexity, a societal culture of violence, and whether help in child rearing is available. Analysis suggests that corporal punishment may be a parent's way to prepare children for societal power inequality.

This article discusses two different explanations of male initiation ceremonies. Evidence is also presented that suggests that psychological conflict might strongly predict male initiation in the presence of the following catalysts: nonmatrilocal residence, nonstate political organization, and warfare.