A cross-regional examination of camelid herding practices in Peru from 900 BCE to 1450 CE: Insights from stable isotopes in camelid bone collagen and fiber.

The economic, socio-political, and cultural significance of camelids in the Andean region is well-recognized, yet an understanding of their management evolution over pre-historical periods remains limited. This study aims to fill this gap by conducting the first cross-regional assessment of camelid pastoralism in Peru from 900 BCE to 1470 CE, using stable carbon and nitrogen isotopic compositions from the bone collagen and fibers of 577archaeological camelids across 21 sites. This research investigates the spatio-temporal shifts in camelid dietary habits, focusing on how the rise of intensive agriculture may have influenced change and led to the evolution of distinct roles for camelids in coastal versus non-coastal Andean economies.

Identifying key socioecological factors influencing the expression of egalitarianism and inequality among foragers.

Understanding how resource characteristics influence variability in social and material inequality among foraging populations is a prominent area of research. However, obtaining cross-comparative data from which to evaluate theoretically informed resource characteristic factors has proved difficult, particularly for investigating interactions of characteristics. Therefore, we develop an agent-based model to evaluate how five key characteristics of primary resources (predictability, heterogeneity, abundance, economy of scale and monopolizability) structure pay-offs and explore how they interact to favour both egalitarianism and inequality.

Climate change-induced population pressure drives high rates of lethal violence in the Prehispanic central Andes.

Understanding the influence of climate change and population pressure on human conflict remains a critically important topic in the social sciences. Long-term records that evaluate these dynamics across multiple centuries and outside the range of modern climatic variation are especially capable of elucidating the relative effect of—and the interaction between—climate and demography. This is crucial given that climate change may structure population growth and carrying capacity, while both climate and population influence per capita resource availability.

Climate and demography drive 7000 years of dietary change in the Central Andes.

Explaining the factors that influence past dietary variation is critically important for understanding changes in subsistence, health, and status in past societies; yet systematic studies comparing possible driving factors remain scarce. Here we compile the largest dataset of past diet derived from stable isotope δC‰ and δN‰ values in the Americas to quantitatively evaluate the impact of 7000 years of climatic and demographic change on dietary variation in the Central Andes. Specifically, we couple paleoclimatic data from a general circulation model with estimates of relative past population inferred from archaeologically derived radiocarbon dates to assess the influence of climate and population on spatiotemporal dietary variation using an ensemble machine learning model capable of accounting for interactions among predictors.

The Marginal Utility of Inequality : A Global Examination across Ethnographic Societies.

Despite decades of research, we still lack a clear explanation for the emergence and persistence of inequality. Here we propose and evaluate a marginal utility of inequality hypothesis that nominates circumscription and environmental heterogeneity as independent, necessary conditions for the emergence of intragroup material inequality. After coupling the Standard Cross-Cultural Sample (SCCS) with newly generated data from remote sensing, we test predictions derived from this hypothesis using a multivariate generalized additive model that accounts for spatial and historical dependence as well as subsistence mode.