The authors contribute to a growing body of theory which posits cultural differences as a result of variable pathogen prevalence by testing the relationship between pathogen richness and various measures of conformity in a cross-regional sample. After controlling for confounds such as life expectancy, GDP, population density, arable land area, and agricultural labor force, the authors suggest that conformity is emphasized to varying degrees in response to the increased vulnerability to pathogens generally associated with deviation from normative social conduct.

This book discusses the characteristics of adolescence cross-culturally and examines the differences in the adolescent experience for males and females. Several relationships are tested in order to gain an understanding of cross-cultural patterns in adolescence.

In order to evaluate an adaptive justification for restriction of ritualized physical contact, the authors test association between three manifestations of physical interaction and prevalence of pathogens cross-culturally. Their expectation, supported by two of the three tested hypotheses, is that higher pathogen prevalence will lead to customs of restricted physical contact. Both cultural and biological evolution are suggested to be influential in selecting for physically intimate behaviors.

This article tests a myriad of factors that may have contributed to the adoption of monogamy in preindustrial societies. Results indicate that monogamy is not imposed by elites; rather, it is a strategy often chosen by women who can see no advantage to increasing the size or economic productivity of their households with more wives. The authors also assert that monogamy is generally adopted through cultural diffusion. Low pathogen stress, low risk of famine, and low endemic violence are also correlated with monogamy.

This article tests four hypotheses regarding scarification, which is described as 1) a rite of passage, 2) a hardening/trauma procedure, 3) a nonadaptive sexually selected character, or 4) an adaptive pathogen driven sexually selected character. Only the third hypothesis is supported in a worldwide sample, suggesting that scarification is associated with polygyny. The other three are each supported in different regional subsamples—principally the first hypothesis (supported in Africa, the Insular Pacific, and South America).

This study examines the relationship between body scarification and pathogen prevalence. Authors hypothesize that risk of serious pathogens will be related to scarification on areas of the body that are associated with physical attractiveness and fertility. Results show that only female stomach scarification is significantly related to pathogen prevalence.

This article builds on previous cross-country and cross-state research into Tightness-Looseness (TL) theory, which proposes relationships between the incidence of ecological threat and cultural tightness, as well as tightness’ downstream effects on belief in a moralizing high god, inter-group contact and authoritarian leadership. To evaluate the generalizability of TL theory beyond complex cultures, the authors test these relationships among 86 nonindustrial societies from the ethnographic record. A structural equation model is presented of the results for nonindustrial societies; it is generally in accord with previous findings from more complex societies. Because the nonindustrial sample is more variable, they also look at relationships between societal complexity and kinship heterogeneity, aspects that vary in nonindustrial societies.

This article employs cross-national and cross-cultural methods to investigate whether pathogen stress is a direct determinant of authoritarianism. The study controls on other factors such as famine, warfare, and malnutrition and evaluates alternative causal models.

The authors test the relationship between linguistic diversity and parasite richness, theorizing that anti-pathogen behaviors, such as the favoring of contact with a limited range of similar, nearby populations carrying the same suite of parasites and pathogens, will be selected for due to variability in immunobiological makeup between groups. As a result, cultural and gene pool isolation will be likely to further divide local parasite-host groups, generating language diversity as well as population divergence and new evolutionary forms among the parasites themselves. A significant positive correlation is found, which the authors suggest has important implications for future research regarding cross-cultural transmission and interaction.

Authors contend that many of the differences across the 50 states can be attributed to the degree to which social entities are "tight" (have many strongly enforced rules and little tolerance to deviance) or "loose" (have few strongly enforced rules and greater tolerance for deviance). Significant correlations were found between many state characteristics and tightness-looseness.