This study reports on a structural analysis which is suggested to confirm and expand upon Nadel's (1951) hypothesis that friendly equality between grandparents and grandchildren appears only with certain patterns of authority in the family.

Evolutionary anthropologists have long emphasized the puzzle of short inter-birth intervals, extended childhoods, and long post-reproductive lives of humans, in particular the problem it poses for raising children. While there is agreement that mothers receive assistance from kin to offset the high costs of raising children, opinion is equivocal as to which kin help and to what extent they help. Here the authors review 45 studies from historical and contemporary natural fertility populations to assess the effects of various types of kin on child survival rates.

After noticing that there are no cross-cultural phylogenetic studies of grandparent terminologies, the authors use the record from 134 Pama-Nyungan languages to explore the evolution of this kinship category and to evaluate the effects of social structures in this evolution. The authors suggest that there used to be four different terms for grandparents in the proto-Pama-Nyungan language family, which was supported by the data. The results show no evidence of co-evolution between these grandparent systems with neither community marriage organization nor post-marital residence. There is not a significant correlation between grandparent and cross-cousin terms; however, there is some evidence that grand-child terms are correlated to grandparent systems.

Seeking to resolve contradictions between previous studies, these authors conduct empirical analysis on the relationship between population size and cultural evolution. Results indicate that population size influences toolkit richness and complexity, even when proxies for risk of resource failure are introduced in the regression model. Authors speculate that the association is weaker for hunter-gatherers because those societies are more affected by risk of resource failure and have institutions that facilitate cultural evolution despite smaller population size. There also may be a threshold effect in the influence of population size on toolkit structure.

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.

Previous studies have yielded contradictory results on the relationship between population size and cultural evolution. Focusing on tool complexity these authors introduce the risk of resource failure as a possible confounding variable. They conclude that population does not predict tool kit complexity when controlling on other factors. There were significant correlations between tool kit complexity and some of the resource measures.

This article uses factor analysis to identify the key variables underlying the many cross-cultural associations reported by Textor (1967). Twelve factors are identified.

High infant and child mortality rates are suggested to be one of the most enduring and important features of ancestral human environments, referred to as the Environment of Evolutionary Adaptedness (EEA). These rates contrast with the very low rates of infant and child mortality among many industrialized nations since the 19th and 20th centuries. The authors compare data from recent hunter-gatherer and agricultural societies, historical records, and non-human primates in attempt to quantitatively describe infant and child mortality rates during the EEA.

Can physiological variation in human populations be attributed to environmental variables? Arguing for the importance of phylogenetic comparative methods, the authors present the results of previous research by Holden & Mace (1997) on lactose intolerance as well as introduce new research on sex ratio at birth. The authors suggest that global variance in sex ratio at birth is an adapted response to the physiological costs of giving birth to boys in high fertility populations.

This textbook chapter outlines relationships between kinship and socialization. It also uses a three-point scale to describe the variation in enculturation processes for a sample of 128 societies. Without presenting a formal test, the author concludes that enculturation (as he measures it) is weaker in industrialized societies than in those without industrialization or urbanization.