This paper examines the influence of traditional leaders, or "chiefs," in sub-Saharan Africa, and how their power varies within and among 19 African countries. The authors argue that the power of traditional chiefs is influenced not only by state policies of indirect rule, as previous research has suggested, but also by local factors such as land quality. They find that traditional chiefs have more power in areas with higher agricultural potential and land quality, likely because citizens in these areas rely on traditional chiefs to define and defend their land rights beyond the protections provided by state institutions. The authors suggest that while land quality may not have been an important factor in state formation in the pre-colonial period, it has become increasingly important in the past half century as population densities have increased and agriculture has become more intensive. Controls are also introduced.

In this study, the authors examine pathways to social inequality, specifically social class hierarchy, in 408 non-industrial societies. In a path model, they find social class hierarchy to be directly associated with increased population size, intensive agriculture and large animal husbandry, real property inheritance (unigeniture) and hereditary political succession, with an overall R-squared of 0.45. They conclude that a complex web of effects consisting of environmental variables, mediated by resource intensification, wealth transmission variables, and population size all shape social inequality.

This study explores the evolution of family systems in non-industrial agricultural societies based on environmental conditions. First, the authors conduct a multi-evolutionary simulation for each family system: absolute nuclear families (nuclear with unequal inheritance), egalitarian nuclear families (nuclear with equal inheritance), stem families (extended families with unequal inheritance), and community families (extended families with equal inheritance). Second, they use Spearman's rank correlation analyses to assess the relation between the 186 non-industrial societies and the types of inheritance relationships, either parent-child (nuclear or extended) or inter-sibling (strongly biased or equal). The results show that the four core family systems are related to wealth and land resources. Other relevant findings are that low polygyny is related to agricultural societies, higher poverty levels to extended families, and accelerated wealth accumulation to strongly biased inheritance.

The authors use a comparative ethnoarchaeological model that seeks to test the applicability of Dynamical Systems Theory to modeling subsistence variation (namely the foraging-farming transition). The authors utilize the concepts of "attractors," which tend to stabilize a system, and "repellors," which tend to be destabilizing forces. Authors hope that this multidimensional approach, which assumes that several "controlling" variables disproportionately affect change within subsistence systems, will adequately model the nonlinearity and heterogeneity seen in the emergences of (and variations within) human subsistence systems throughout human history. Their model and premises regarding disproportionally-controlling variables appear to be supported.

This article examines the conditions under which slavery occurs in preindustrial societies. Results suggest that social stratification and the existence of open resources are both necessary conditions for the occurrence of slavery.

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 book investigates the conditions necessary for the success of slavery as an industrial system. Findings indicate that free land and subsistence dependent on capital are necessary for the existence of slavery.

This paper examines the relationship of productive variation in land between ethnic groups to determine if an increased range of producible goods will increase trade, thus decreasing language diversity between neighboring groups. The author initially found that high-variation in land production lessened the diversity of language between ethnic groups in that area. To further test this correlation, the author found that high-productive variation increased trade and exogamous marriage and decreased inter-ethnic conflict. Based on these findings, the author suggests that neighboring ethnic languages co-evolved through the economic benefit of inter-ethnic trade and social interaction.

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.

This paper seeks to understand the roles played by children and adolescents in hunter-gatherer societies in relation to their social and ecological context. The authors set out to investigate how environmental factors, ecological risk, and the energetic contributions of adult men and women to food production may have influenced children/adolescent allocation of time to child care, domestic work, food production, and play. In order to carry out this study, the authors logged the behaviors of 690 children and adolescents from twelve hunter-gatherer and mixed-subsistence societies (Agta, Aka, Baka, BaYaka, Dukha, Hadza, Matsi-genka, Maya, Mayangna, Mikea, Pume, and Tsimane), totaling 85,597 unique observations. The study found that harsh environmental factors were not associated with child/adolescent time allocation, but that local ecological risk such as dangerous animals and lack of water availability predicted decreased time allocation to child care and domestic work, and that increased adult female participation in food production was associated with less time invested in child care among boys. It also found that all gendered differences in time allocation among children were stronger when men made greater contributions to food production than women. The authors interpret these results to signify that parents may play a role in preparing their children for environmental and ecological difficulty in order to help them develop skills that will help them become useful community members as adults.