How is the evolution of language shaped by speaker population size? Through comparative data analyses of 153 language pairs from the Austronesian, Indo-European, and Niger-Congo language families, the authors find that the influence of population size on language evolution is not the same in the three language families. Only in Indo-European languages did a smaller population size of language-speakers significantly predict more word loss.

How do subsystems of language evolve over time? It is commonly assumed that grammatical changes of language are slower than vocabulary changes. Using a Dirichlet process mixture model to analyze rates of language evolution in 81 Austronesian languages, the authors find that to the contrary, the grammatical features of language tend to change at a faster rate than basic vocabulary. Furthermore, their results show that grammatical features have higher rates of homoplasy, more frequent contact-induced change, and less deliberate differentiation than basic vocabulary.

The authors implement an anthropological approach to explore the evolutionary and cultural explanations of modern obesity. Three widely accepted facts are considered: (1) gender dimorphism (women having higher levels of fat), (2) increase of obesity with modernization, and (3) a positive association between obesity and socioeconomic status. Using theory, cross-cultural research, and case studies, the authors hypothesize how obesity may have been selected for (or not selected against) in an evolutionary context considering both biological and social factors.

In this study, the authors examine pathways to social inequality, specifically social class hierarchy, in 408 non-industrial societies. In a path model, they find social class hierarchy to be directly associated with increased population size, intensive agriculture and large animal husbandry, real property inheritance (unigeniture) and hereditary political succession, with an overall R-squared of 0.45. They conclude that a complex web of effects consisting of environmental variables, mediated by resource intensification, wealth transmission variables, and population size all shape social inequality.

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.