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.

In the field of bioacoustics, the Acoustic Adaptation theory suggests that variation in vocalization across different species can be accounted for by the acoustic properties of different habitats. Here, the researchers test consonant- and vowel-heaviness in human languages against various environmental variables in order to examine the theory's potential application to our own species. The authors identify a significant negative correlation between consonant heaviness and temperature, precipitation, and tree cover, and some positive correlation with rugosity and elevation as their most important findings, while acknowledging the potentially influential roles of migration and demographic factors in producing this relationship.

Inter-group variation is greater in humans than in any other animal, and scholars continue to debate the cause of this diversity. Two competing explanatory models of human variation emphasize either (1) ecological differences and "evoked" culture or (2) population-level effects of cultural transmission. The former emphasizes mechanisms that operate within a single generation, while the latter emphasizes cumulative cultural history operating over many generations. To test these competing models, the authors measured the relative power of ecological variables as compared to culture history to predict behavioral variation in 172 western North American tribes. Culture history is subdivided into culture phylogeny (based on language phylogeny) and spatial distance.

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.

It has long been suggested among linguists that geographic boundaries between dialect communities correlate with ecological, environmental and even infrastructure-related boundaries on the landscape. This article tests that hypothesis quantitatively, using a suite of spatial statistics to test for autocorrelation between environmental factors within a series of dialect regions throughout Colombia. The authors find that several variables (including precipitation, agroclimatic suitability and access to roads) show significant spatial dependence within dialect regions.

The researchers, using principal component analysis, generalized additive models across 12 agriculture origin locations, and a model predicting hunter-gatherer population density, evaluate hindcasted population density trends to suggest predictors of the development of agriculture. Using domestication as an indicator of agriculture, they test 3 competing hypotheses regarding agriculture development. Their results are consistent with the "surplus" hypothesis, indicating that agriculture arose as population densities increased along with environmental capabilities.

Jared Diamond previously argued that the East-West orientation of Eurasia allowed for the spread of substantial cultural, political, technological, and military innovations, due to environmental homogeneity across the continent. The authors of this article test this theory through quantitative analyses. Their results suggest that ecology can indeed influence the potential for cultural transmission, consistent with Diamond's theory. However, the authors do not find support for Eurasia having lower environmental barriers to cultural transmission in comparison to other continents.

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.

This paper poses and tests relationships between local spatial variability of rainfall and property rights, as well as the degree of hierarchy, across 41 different tribal societies in Sudan. The authors find that there is a significant negative relationship between rainfall variability and degree of hierarchy. They also find that in the presence of local rainfall variability in Sudan, members of a tribe are more likely to establish common property institutions that allow access to all members.

In this article, the authors seek to determine cross-culturally valid predictors of dominant types of human subsistence around the world. They did this by formulating multiple models that incorporate different combinations of environmental, geographic, and social factors. These models were then used to test various hypotheses posed throughout the anthropological literature surrounding factors that determine dominant subsistence strategies.