This study examines the variation in responses to sexual infidelity and the effect of social complexity and descent on responses to infidelity. Results suggest significant relationships between social complexity, descent, and responses to infidelity

The author performs tests of hypothesized relationships between arranged marriage and various forms of non-sanctioned mate choice. Overall, the author theorizes that where marriages are arranged, mate choice will be found in higher prevalence of premarital sex, extramarital sex, and rape. Most tests support these relationships in the hypothesized directions, suggesting that strict regulation of marriage provides parents with some, but far from complete control over the mate choice of their offspring.

In an effort to better understand variation in jealous response cross-culturally, the researchers of this study surveyed 11 different populations, eight of which were small-scale societies on five different continents (Mayangna, Shuar, Tsimane, Himba, Hadza, Karo Batak, Mosuo, and Yasawa) and three of which were in urban settings (Los Angeles, CA, "urban India" (online), and Okinawa, Japan). Looking at the differences between sexual and emotional infidelity, researchers found that greater paternal investment and lower frequency of extramarital sex are associated with more severe jealous response.

This book examines population growth rate and its correlates by testing 274 hypotheses (derived from multiple theories) with an 18-society sample. Forty-one of these hypotheses were significant at the .05 level, leading the author to accept these relationships as reflective of the real world. The 274 hypotheses are grouped into 51 broader hypotheses, and marked by (*) where relationships are significant as designated by the author or by significance p < 0.05.

This article examines the "sexual conflict" hypothesis which predicts that male genital mutilation should be associated with polygyny and a reduction in the frequency of extramarital sex. Male genital mutilation (MGM) rituals should be highly public and facilitate access to social benefits. Support for these assumptions is provided.

Based on work by Rosenblatt (1966), this article tests a hypothesis relating sexual freedom to romantic love. Findings suggest a relationship between premarital and extramarital sexual permissiveness equality for women and men and romantic love.

This article examines the relationship between social structures and sexual jealousy. Results suggest that social structures that emphasize the importance of pair-bonding, progeny, personal property, and exclusive marital sex relations are associated with sexual jealousy in males.

This study is a comprehensive analysis of female and male genital mutilation/cutting (FGM/C and MGM/C) practices, including their history and socio-ecological correlates, using a phylogenetic cross-cultural framework. It employed two global ethnographic samples, the Ethnographic Atlas (EA) and the Standard Cross-Cultural Sample (SCCS), and two subsets of the phylogeny (supertree) of human populations based on genetic and linguistic data, to investigate the variables that may have led to the introduction of these practices, and to determine where and when they may have originated. The study suggests that MGM/C probably originated in polygynous societies with separate residence for co-wives, supporting a mate-guarding function, and that FGM/C likely originated subsequently and almost exclusively in societies already practicing MGM/C, where it may have become a signal of chastity. Both practices are believed to have originated multiple times, some as early as in the mid-Holocene (5,000–7,000 years ago). The study posits that GM/C co-evolves with and may help maintain fundamental social structures and that the high fitness costs of FGM/C are offset by social benefits, such as enhanced marriageability and social capital.

This study investigates political organization and the punishment of nonmarital sex. The author suggests that "the rules governing each type of nonmarital relationship are outgrowths of different relationships between controlling political bodies and local boundary systems."

Apostolou examines the argument that most of human evolution occurred in an environment where individuals had limited opportunity to exercise choice. This argument derives from evidence indicating that among contemporary and ancestral postindustrial societies, mate choice is regulated by parents choosing their children's spouses. Results from the present study show that in an arranged marriage setting, there is still space for individuals to exercise choice in mates (through premarital and extramarital relationships, as well as rape). Apostolou discusses possible explanations for these findings, as well as their evolutionary significance.