The Trivers-Willard hypothesis posits that concentrations of human milk immune factors vary with maternal condition (maternal diet diversity and body mass index) and the sex of the infant. Using linear mixed-effects models to analyze 358 milk samples from 10 international sites, the authors find minimal support for the Trivers-Willard hypothesis; only one immune factor, IgG, exhibited a significant relationship.

After studying Paiute society, the author postulates that sorcery may serve as a mechanism for social control in societies lacking superordinate authority justice. In this chapter, the cross-cultural results were presented.

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.

Authors suggest that suicide is more likely to occur in contexts where an individual's social ties are threatened, weakened, or broken, causing social dislocation (thwarting-disorientation contexts). Results support this hypothesis.

This article tests differing theories of why a man's marriage of his mother's brother's daughter is often encouraged while marriage of the father's sister's daughter is discouraged. Maintenance of relationships between bride-givers and bride takers is considered, as are the role of childhood sentiments in choosing a spouse.

In this study of 80 societies, the author initially sets out to test the theory that if social customs and rules forbid satisfaction of sexual impulses, "civilization" will be built based on sacrifices of these desires.

This article tests the effect of environmental risk on parental investment, differentiating between maternal and paternal care. Results indicate that the saturation point of parental investment may be a function of environmental risk, as parental care experiences diminishing returns due to extrinsic risks.

This study examines the relationship between pairbonds and lactation, specifically the relationship between pairbond stability, alloparenting, and cross-cultural trends in breastfeeding. Findings show that both conjugal stability and availability of alloparental care are associated with age at weaning.

This article explores differences between "tight" cultures ("have many strong norms and low tolerance of deviant behavior") and "loose" cultures ("have weak social norms and high tolerance of deviant behavior"). The tightness-looseness measure manifests in a myriad of macro and micro phenomena, from governance and religiosity to individual psychological processes. This study investigates these phenomena in modern nations rather than traditional societies. Potential ecological, historical, and socio-political predictors of tightness-looseness are also examined.

This study employs a psychological theory and builds on the holocultural literature on male homosexuality. Two hypotheses relating homosexual behavior among men to social constructs for sexuality (the couvade, male transvestism) are derived from a study by Munroe (1980). The hypotheses are tested and supported in a sample of cultures drawn from Munroe's codes and the Human Relations Area Files.