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.

This article employs archaeoethnology to investigate possible patterns of synchronous population growth among cities of the prehistoric New World. The author finds a pattern of settlement synchrony distinct from a pattern found in the prehistoric Old World, suggesting that global climate change may not be a key factor in understanding settlement synchrony. Macroregional political and economic processes such as long-distance trade are offered as partial explanations of settlement synchrony in the New World.

This chapter is concerned with correlates of warlikeness among non-industrial societies. Findings indicate that warlikeness is associated with climate, mobility, subsistence, political integration, division of labor, culture contact.

In this paper, the authors utilize phylogenetic methods to reconstruct the evolution of land tenure norms among 97 Austronesian societies. They coded these norms for each society as none (N), group (G), group-kin (K), and individual (I). After formulating various models of evolution through these various stages, they used Bayesian analysis to determine support for each. They conclude with remarks about this type of evolutionary phylogenetic research as a form of "virtual archeology."

This paper investigates two mechanisms of cultural evolution: peaceful diffusion and warlike migration. Two societies, one for each mechanism, were compared to a base society on 11 culture traits. Eight of the 11 traits diffused more readily through peaceful borrowing than through warlike migration. The authors conclude that eliminating warlike migration would slow cultural evolution but that peaceful borrowing is a favored mechanism for culture contact and change.

The author hypothesizes that the level of disruption caused by a cargo cult varies directly with the degree to which indigenous people become separated from the agents of Western culture directly prior to the cult outbreak. Results support this hypothesis.

This article explores the following questions: What environmental and cultural factors might explain variation in prejudice across cultures? Do these factors explain the intention to vote for nationalist politicians? The authors perform seven studies, focusing on the link between cultural tightness and the rise of prejudice in cultures. They theorize that cultural tightness is positively correlated with the rise of prejudice against people perceived as disrupting the social order. From this theory, they suggest three hypotheses: 1) cultural variation in tightness is related to cultural variation in prejudice, 2) cultural tightness is related to the support for nationalist politicians, and 3) cultural tightness is a link between ecological threats and prejudice. The results support these hypotheses, offering a cultural evolutionary perspective on prejudice.

Is grammatical complexity shaped by sociodemographic and sociolinguistic factors? The previously accepted "linguistic niche hypothesis" claims that with an increased number of nonnative speakers in a social group (high exotericity), grammatic complexity decreases; on the other hand, grammatical complexity increases amongst isolated linguistic communities (low exotericity). Through the use of spatiophylogenetic modelling of 1314 languages, the authors of this study do not find adequate evidence to support the linguistic niche hypothesis. Instead, they suggest that linguistic complexity is better predicted by phylogeny and geographic contiguity.

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.

This article explores the relationship between language structure and social environment, positing that linguistic factors such as morphological complexity are associated with demographic/socio-historical factors such as number of speakers, geographic spread, and degree of language contact. Data support such an association. The authors further propose a Linguistic Niche Hypothesis suggesting that “the level of morphological specialization is a product of languages adapting to the learning constraints and the unique communicative needs of the speaker population” (7).