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 author analyzes 76 societies synchronically, positing that the evil eye belief functions as a useful heuristic and prosocial/cohesive element in weakly-institutionalized societies with significant wealth inequality; in particular, the evil eye belief is found to be more prevalent in agro-pastoral societies where material wealth is vulnerable and plays a dominant role in subsistence economy.

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.

The article discusses the role of land ownership in natural resource management and social-ecological resilience, and explores the factors that determine ownership norms in human societies. The study tests long-standing theories from ecology, economics, and anthropology regarding the potential drivers of land ownership, including resource defensibility, subsistence strategies, population pressure, political complexity, and cultural transmission mechanisms. Using cultural and environmental data from 102 societies, the study found an increased probability of land ownership in mountainous environments and societies with higher population densities. The study also found support for the idea that neighboring societies might influence land ownership. However, there was less support for variables associated with subsistence strategies and political complexity.

The authors examine multiple ecological variables as possible predictors of language diversity in North America using path analysis, mechanistic simulation modelling, and geographically weighted regression. They conclude that many of the variables do not predict language diversity, but rather are mediated by population density. The authors also find that the variables' ability to predict is not universal across the continent, but rather more regional.

The authors investigate the relationship between linguistic diversity and various environmental and spatial variables associated with biodiversity. Most of these variables predict linguistic diversity variably across different continents, and more so within Africa and extended Asia (Asia, the Pacific, and Australia) than within Europe and the Americas. This divide is theorized to be a result of differences in demography and impact of colonialism between the two global regions. However, two environmental factors, landscape roughness and density of river systems, are found to be significant predictors across all global regions. The authors suggest that, as in processes of speciation, rough terrain and watercourses both create physical barriers between which languages can develop in isolation while, in the case of river junctions, also providing transportation routes whereby hybrid languages can occasionally manifest.

This article investigates commonly accepted theories that purport to explain political centralization and investigate their relevance to sub-Saharan Africa. The leading ideas for the formation of political centralization using a worldwide sample include population density, inter-state warfare, and trade. However, the authors reported these factors are not predictive of the sub-Saharan Africa sample. The authors suggest that the lack of agricultural productivity in sub-Saharan Africa may have stunted population density therefore inhibiting political centralization and that Africa’s poor economic performance is, in part, due to lack of political centralization.

Belief in moralizing high gods (MHGs) has been theorized as a response to unfavorable environments, as a way to normalize behavior. In this study, researchers test the theory by creating a model for predicting the distribution of MHGs. They run many alternative models, testing the effects of resource abundance, climate stability, and pertinent social factors on the occurrence of belief in MHGs. Based on the ten most supported models, they create an average model that predicts MHGs within cultures with “excellent” accuracy.

An early cross-cultural study that sought to establish correlations between "stages" of economic culture and a variety of different social and political institutions, such as form of government and justice, marriage and kinship, and behaviors during warfare.

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.