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.

Considerable disagreement exists in regard to the origin and distribution of economic phenomena such as money, slavery, markets, exchange, and imbalanced transfers. Here the author utilizes a worldwide cross-cultural sample of 60 pre-industrial "societies" to empirically test many economic hypotheses, with a focus on distributional mechanisms and institutions.

This study examines three theories of the origin of the plow. The author rejects the universalist approach on the basis that not all cultures that are aware of the plow adopt its use. Findings provide partial support for a theory focused on population density, particularly the importance of fallowing practices and labor productivity. The author’s own ecological approach, pointing to a culture’s staple food as a crucial variable, also receives empirical support.

This article presents a representative theoretical model of the transition to agriculture. Empirical results from a cross-cultural sample provide support for the model. Results suggest that agriculture is associated with population density, technological sophistication, environment, and proximity to agricultural hearths, such as the Fertile Crescent.

This article explores the relationships between habitat and social organization among humans and other species. Diet, technology, group size, home range, mobility, kinship, marital residence, sexual division of labor, mating system, central places, food sharing, and egalitarianism are all considered.

Researchers investigated further into why and how humans speak so many languages across the globe, and why they are spread out unevenly. Using two different path analyses, a Stationary Path analysis and a GWPath, researchers tested the effect of eight different factors on language diversity. Out of the eight variables (river density, topographic complexity, ecoregion richness, temperature and precipitation constancy, climate change velocity, population density, and carrying capacity with group size limits), population density, carrying capacity with group size limit, and ecoregion richness had the strongest direct effects. Overall, the study revealed the role of multiple different mechanisms in shaping language richness patterns. The GWPath showed that not only does the most important predictor of language diversity vary over space, but predictors can also vary in the direction of their effects in different regions. They conclude that there is no universal predictor of language richness.

This paper builds off previous research into the effect of population size and resource risk on complexity of subsistence technology by investigating the relationship between these independent variables and total number of material items and techniques used by various western North American hunter-gatherer groups. This tally of total technological complexity is found to be insignificantly related to population size or residential mobility; however, there is a significant correlation in the expected direction between technological complexity and one measure of resource risk (mean annual temperature during driest month). Tying this finding to previous analyses of subsistence technologies, the authors theorize that environmental risk is a pervasive driver of technological ingenuity and cultural evolution.

This article focuses on the effect of environmental extremes and unpredictability on human behavior and reproductive strategies. Significant correlations were found between environmental extremes and unpredictability and several variables, including mobility, subsistence mode, and degree of polygyny.

This article tests a broad hypothesis that slavery is an inevitable stage in society's economic development. The author rejects this hypothesis; he argues that there are two main types of slavery (slaves for economic capital or social capital) and each type has its own set of social and politcal determinants. Overall, the power dynamic between husbands and wives is thought to be a key predictor of slavery.

Researchers investigated the variation of land tenure systems across forager societies using the economic defensibility model. The study attempted to explain the variation in tenure systems across 30 hunter-gatherer societies. Using data on defense and sharing of resources among groups, and indicators of resource density, resource predictability, and competition for resources, the researchers were unable to explain the variation. This study highlights the vast range of diversity and complexity of foragers subsistence strategies, and proposes that it may be more telling to conceptualize tenure systems among hunter-gatherer societies as assemblages of multiple property regimes. While there was no overall evidence that environmental variables of resource density and predictability explain variation in tenure systems, researchers did find that increasing population density, and greater competition for resources leads to greater territoriality.