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 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.

The second and third parts of this book classify the economic systems of foraging and agricultural societies in the SCCS based on correlations between their institutions of property an distribution. These economic types are then examined for relationships with other social, political, demographic, and environmental factors in order to draw tentative conclusions regarding the origins of the Agricultural and Industrial Revolutions. The fourth part of the book uses cross-national data to examine similar associations in industrial/service economies, and is not included here.

This article tests some conditions that may lead to the emergence of unilineal descent, focusing on unilocality and warfare. Unilineal descent is thought to be likely in a unilocal society without a centralized political system that is experiencing intra- or inter-societal warfare. The authors also posit that a "clan" system usually develops prior to a "lineage" system.

While it is widely accepted that there are a multitude of variables that contribute to a society’s level of democracy, the authors of this study argue that the prevalence of consanguinity is one that is often overlooked. Using a sample of 70 nations, they tested the relationship between consanguinity (defined as marriage and subsequent mating between second cousins or closer relatives) and level of democracy (defined by both the Polity IV scale and the EIU Index) and found a significant negative relationship. Similarly, when controlled for a host of different variables in multiple regression analysis, the significant relationship between consanguinity and level of democracy held true.

This study follows the theoretical construct of general cultural tightness and looseness (TL). Tightness is thought to be adaptive when facing socioecological threat, such as resource stress, since it involves a greater amount of cooperation. The study asks: "Why do some societies have relatively standardized or uniform clothing and adornment, whereas others have considerable variability across individuals?", which is connected to the broader question of why some societies show more within-group variation. The authors use a sample of 80 non-industrial societies from SCSS, to explore the relationship between general cultural tightness and standardization or synchrony in dress. The results support that tighter societies have more uniformity in dress and that resource stress is a predictor of synchrony. However, it is not supported that egalitarian societies have more synchrony, and that tightness is positively predicted by resource stress.

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

This article reviews the literature referring to patterns of marital residence. Discussions include the psychological consequences for the individuals involved, variations in marital residence patterns, explanations of the types of kin or descent groups developed in response to varying marital residence patterns, unisex associations, and consequences of gender-based social organizations.

This paper suggests a tentative analysis of continuous female sexual receptivity based on a random sample of mammals and birds. It is suggested that humans developed continuous female sexual receptivity because humans have the unusual combination of long infant dependency, group living, and male-female bonding.