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.

This article considers the consequences of modernization. Factor analysis is used to identify four stages of modernization: 1) changes in education, government, and trade; 2) changes in health, technology, and transportation; 3) changes in family, religion, and toilet; and 4) changes in behavior. The authors then consider five trends they expect to be associated with modernization and test whether they develop over the course of the four stages. Results indicate that these 5 trends—increased cultural complexity, female status, pacification, suicide, and social stress—are associated with only the first and fourth stages.

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 article tests a series of hypotheses differentiating internal warfare and external warfare. Results support the theory that internal warfare is a population control mechanism more common in patrilocal societies, whereas external warfare occurs between two societies, one of which recently migrated and adopted matrilocal residence. Based on these findings, the authors assert that internal warfare can be regulated while external warfare cannot.

A model for the development of counting systems is tested. The hypothesis presented predicts that unpredictable climate conditions result in inconsistent food supply which leads to the need for food storage and, thus, a system to account for the stored food. Results strongly support this hypothesis.

This study explores possible causes of matrilocal residence. Previous hypotheses are unsupported. Results show a significant relationship between matrilocality and recent migration.

The association between hunting and sign language is examined. It is hypothesized that sign language develops as a form of nonverbal communication to aid hunters in the coordinated stalking of game. Ethnographic evidence supports this hypothesis. A second hypothesis is also tested concerning the relationship between population size and non-verbal communication, however sampling procedures provided an inadequate test of this hypothesis.

This study focuses on the factors associated with the development and persistence of an ideology of male supremacy. Authors identify several realms of culture that show a clear male preference and suggest that warfare is the most significant cause of the male supremacy complex in preindustrial societies. Authors hypothesize that warfare will be positively related to female infanticide. Results support this hypothesis. Another hypothesis relating diet to warfare and infanticide is provided, but not tested.

This article examines cultural forms of population control. Results suggest that female infanticide and warfare are interrelated and effective forms of population control.

This study builds on the work of Melvin Ember (1973) regarding living floor area of dwellings and its relationship to marital residence. The original results are replicated.