Why do humans have long childhoods and slow physical growth rates compared to nonhuman primates? The embodied capital theory (ECT) posits that the hard-to-extract, energy-packed resources sought by humans require more complex cognitive and physical skills, which are acquired during a longer development period. The authors of this article test this theory through a comparative analysis of different forms of resource types and skill level by age in 28 different societies. Their findings support ECT, suggesting that long childhoods evolved as a period to develop the skills required for extracting complex resources in foraging societies.

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.

The author evaluates predictions from the standard model of intensification of food production and suggests it be rejected based on an analysis of 40 societies. The standard model proposes that food producers will increase their energy input until the maximum possible output is achieved, at which point output and labor productivity will fall and producers will invent or adopt new technologies. He then proposes a different model, which he terms the cultural niche construction model. The cultural niche construction model proposes that societies will minimize their energy input while maximizing their returns through continual technological adaptation and niche construction. After predictions from this second model are tested, the author suggests tentatively accepting the cultural niche construction model as a new framework to explain transitions to complex societies.

In this article, the authors reconsider the polygyny threshold model in order to account for the "polygyny paradox." This paradox, as the authors define it, is the trend away from polygyny as societies adopt stratified agricultural economies. This is despite an increase in both the importance of material wealth and greater leaves of wealth inequality both of which would otherwise suggest increased polygyny. The authors develop a new model that does account for this paradox.

The second and third parts of this book classify the economic systems of foraging and agricultural societies in the SCCS based on correlations between their institutions of property an distribution. These economic types are then examined for relationships with other social, political, demographic, and environmental factors in order to draw tentative conclusions regarding the origins of the Agricultural and Industrial Revolutions. The fourth part of the book uses cross-national data to examine similar associations in industrial/service economies, and is not included here.

The authors develop and empirically test a model in which exogamy is negatively predicted by community size, due to decreasing heterogeneity from endogenous marriages in small settlements, and positively predicted by disparity in productivity between communities which is 'smoothed out' by transfer of community members through exogamous marriages. Support for both predictions is found, which is used to argue that cultural traits like marriage customs are heavily influenced by population-environment relationships.

The authors use a comparative ethnoarchaeological model that seeks to test the applicability of Dynamical Systems Theory to modeling subsistence variation (namely the foraging-farming transition). The authors utilize the concepts of "attractors," which tend to stabilize a system, and "repellors," which tend to be destabilizing forces. Authors hope that this multidimensional approach, which assumes that several "controlling" variables disproportionately affect change within subsistence systems, will adequately model the nonlinearity and heterogeneity seen in the emergences of (and variations within) human subsistence systems throughout human history. Their model and premises regarding disproportionally-controlling variables appear to be supported.

Drawing from risk sharing theory, this paper used data from 89 countries to examine the relationship between historic rainfall variation (before 1900) and the emergence of collectivism in, assumed to be, preindustrial societies. Contemporary values of individualistic responsibilities were used under the assumption that they will reflect preindustrial values. Findings support the hypothesis that countries with greater rainfall variation will have less individualism than countries with less rainfall variation. The author then examined rainfall variation and individual responsibility as a proposed catalyst for economic development. Support was found that as individualism increased, so did the economic development of a country.

This study seeks to examine the influence that UV radiation and climate might have on gender inequality, and tests two extant theories on why gender inequality exists -- the life-history theory (aligned with climate) and the cognitive performance theory (aligned with UV radiation). The model with UV radiation as the main predictor fits the data on gender inequality the best, and pathogen prevalence and the ACP1*B allele were also found to be associated with gender inequality. The model was found to be robust across continents and ancestry. The study also highlights the need for further research to better understand the complex interplay of these factors in different cultures.

The researchers examine associations between male status and various measures of reproductive success among foraging/non-foraging, and monogamous/polygynous societies in order to test the "egalitarian hypothesis" which predicts lower status effects in hunter-gatherer groups. Contrary to this hypothesis, they find that male social status is equally significantly associated with reproductive success in foraging and nonforaging societies. Additional support is found for the "mating effort" hypothesis, which predicts that male reproductive success will be more associated with fertility than offspring mortality in polygynous societies, leading the authors to make various suggestions regarding the evolutionary mechanisms at play.