In this paper, the authors argue that polygyny creates social inequality in which economically advantaged men marry multiple women and economically disadvantaged men marry late in life or potentially never. The institution of polygyny results in a higher proportion of single men without families ("excess men"), who, the authors propose, may turn to violence to achieve higher wealth or prestige. Following this theory, the authors hypothesize that societies with more polygynous neighbors will be at higher risk for intergroup conflict, for which they find robust support. They also find that young men in polygynous societies, who are more likely to be economically disadvantaged and have less prestige, are also more likely to feel as though they are treated unequally and more ready to resort to violence, supporting the authors' theorized underlying mechanism.

Using a new measure called "territorial fractionalization" to indicate the extent to which traditional societies are split across current states, the authors of this study propose that fragmentation of ethnic groups and ethnonationalism is key to understanding civil conflict. They find that higher measures of territorial fractionalization significantly predict a higher risk of civil conflict, and that greater increases in territorial fractionalization also predict greater risk of civil conflict. These results hold for a global sample of data from 1945 to 2017, as well as in European and African subsamples dating back to 1886.

Using a new measure called "territorial fractionalization" to indicate the extent to which traditional societies are split across current states, the authors of this study propose that fragmentation of ethnic groups and ethnonationalism is key to understanding civil conflict. They find that higher measures of territorial fractionalization significantly predict a higher risk of civil conflict, and that greater increases in territorial fractionalization also predict greater risk of civil conflict. These results hold for a global sample of data from 1945 to 2017, as well as in European and African subsamples dating back to 1886.

Research sampled 143 societies from the Standard Cross Cultural Sample to test the relationship between honor culture, social rewards for warriors, and intergroup conflicts. Using mediation analysis based on multiple regression, and structural equation modeling, the research supported the theory that honor culture was positively associated with intergroup conflict, and that this relationship was mediated by social rewards for warriors.

Research sampled 143 societies from the Standard Cross Cultural Sample to test the relationship between honor culture, social rewards for warriors, and intergroup conflicts. Using mediation analysis based on multiple regression, and structural equation modeling, the research supported the theory that honor culture was positively associated with intergroup conflict, and that this relationship was mediated by social rewards for warriors.

Research sampled 143 societies from the Standard Cross Cultural Sample to test the relationship between honor culture, social rewards for warriors, and intergroup conflicts. Using mediation analysis based on multiple regression, and structural equation modeling, the research supported the theory that honor culture was positively associated with intergroup conflict, and that this relationship was mediated by social rewards for warriors.

Researchers examine marriage patterns of 186 societies from the Standard Cross-Cultural Sample (SCCS). The eleven predictor variables are pathogen stress, arranged female marriages, population density, father roles during infancy, temperature, social stratification, wealth inequality, internal warfare, assault frequency, female agricultural contribution, and sex ratio. The two outcome variables measuring polygyny are cultural rules constraining polygyny and the percentage of married men who are polygynous. Controlling on phylogeny using a global supertree of the languages, analysis of marriage patterns reveals that assault frequency and pathogen stress are the strongest predictors of polygyny. These findings offer additional support for the theories of harem-defense polygyny and male genetic quality.

This article suggests a general theory of conflict and violence that may help explain the conditions under which internal conflict co-occur or are differentiated.

This article suggests a general theory of conflict and violence that may help explain the conditions under which internal conflict co-occur or are differentiated.

In this article, the authors seek to reevaluate Nolan's (2003) study on the primary determinants of war. They reanalyze his hypotheses with what they claim are more robust measures and methodology. They conclude that there is only a little evidence supporting Nolan's theories, that more productive echnology and higher population density predict war, and that overall ecological-evolutionary and sociopolitical explanations of war are equally supported by empirical data.