Ecological variation & institutionalized inequality in hunter-gatherer societies: presence of defensible clumped resources is a likely determinant of institutionalized hierarchy; predictors such as population pressure & warfare, do not show this effect

Ecological variation and institutionalized inequality in hunter-gatherer societies. Eric Alden Smith and  Brian F. Codding. Proceedings of the National Academy of Sciences, March 30, 2021 118 (13) e2016134118; https://doi.org/10.1073/pnas.2016134118

Significance: Persistent differences in wealth and power are pervasive in contemporary societies, yet were absent or muted for most of human history. To help explain how and why institutionalized hierarchy can arise in egalitarian systems, we examine a sample of Native American hunting and gathering societies that vary in the degree of inequality. Systematic evaluation of alternative hypotheses identifies the presence of defensible clumped resources that can be monopolized as a likely determinant of institutionalized hierarchy. When such resources are present, societies in our study exhibit substantial inequality, including slavery. Other possible predictors, such as population pressure and warfare, do not show this effect. These results suggest general factors likely facilitate the initial emergence of inequality in human societies.

Abstract: Research examining institutionalized hierarchy tends to focus on chiefdoms and states, while its emergence among small-scale societies remains poorly understood. Here, we test multiple hypotheses for institutionalized hierarchy, using environmental and social data on 89 hunter-gatherer societies along the Pacific coast of North America. We utilize statistical models capable of identifying the main correlates of sustained political and economic inequality, while controlling for historical and spatial dependence. Our results indicate that the most important predictors relate to spatiotemporal distribution of resources. Specifically, higher reliance on and ownership of clumped aquatic (primarily salmon) versus wild plant resources is associated with greater political-economic inequality, measuring the latter as a composite of internal social ranking, unequal access to food resources, and presence of slavery. Variables indexing population pressure, scalar stress, and intergroup conflict exhibit little or no correlation with variation in inequality. These results are consistent with models positing that hierarchy will emerge when individuals or coalitions (e.g., kin groups) control access to economically defensible, highly clumped resource patches, and use this control to extract benefits from subordinates, such as productive labor and political allegiance in a patron–client system. This evolutionary ecological explanation might illuminate how and why institutionalized hierarchy emerges among many small-scale societies.

Keywords: evolutionary ecologyhierarchyeconomic defensibilitypatron-client systems