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

Abstract

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 δ13C‰ and δ15N‰ 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. Results reveal that climate and population strongly predict diet (80% of δ15N‰ and 66% of δ13C‰) and that Central Andean diets correlate much more strongly with local climatic conditions than regional population size, indicating that the past 7000 years of dietary change was influenced more by climatic than socio-demographic processes. Visually, the temporal pattern suggests decreasing dietary variation across elevation zones during the Late Horizon, raising the possibility that sociopolitical factors overrode the influence of local climatic conditions on diet during that time. The overall findings and approach establish a general framework for understanding the influence of local climate and demography on dietary change across human history.

Climate change intensified violence in the south-central Andean highlands from 1.5 to 0.5 ka

“…Our results support the hypothesis that drought predictably elevates interpersonal violence rates under certain ecological and sociological conditions, but there is considerable response variation around the mean. This supports previous research demonstrating a relationship between climatological factors and human behavior in the Andes (McCool et al, 2022a, b;Wilson et al, 2022), California (Allen et al, 2016), Mesa Verde (Schwindt et al, 2016), and Amazonia (Neves, 2009;Bush et al, 2021).…”

The role of farming and fishing in the rise of social complexity in the Central Andes: a stable isotope perspective

“…In the Central Andes, an increase in settlement density suggests that population growth rates were particularly high between 2000–1 BCE 16 . This is consistent with other empirical evidence for population increases during the Formative period (3000–1 BCE), including larger size and agglutinated distribution of settlements, as well as changes in domestic architecture 17 – 19 .…”

The alteration from agricultural to nomadic regimes resulted in human livelihood transformation in North-Central China during the 12th century: The archaeobotanical evidence

“…Changes in the geopolitical patterns in historical periods have been demonstrated to significantly affect the agricultural structure (Messer, 1997;Han, 1999;Wilson et al, 2022). There were multiple powerful regimes existing in Northern China during the 10th-13th centuries, with frequent conflicts between regimes and significant changes in their territories, which might be related to the changing situation of agricultural systems in this period (Han et al, 2012;Ma et al, 2020;Shi et al, 2022).…”

“…The archaeobotanical analysis is an important method for understanding the historical evolution of agriculture and has been carried out in different parts of the world during the historical periods, bridging the gaps in studies of ancient agriculture (Kennett and Marwan, 2015;Zhao, 2020). Previous interdisciplinary studies have proposed that geopolitics replaced climate change as the key driver in historical changes in agriculture (Shi et al, 2022;Wilson et al, 2022), such as those in the Central Andes (Kennett and Marwan, 2015;Wilson et al, 2022), in Europe (Messer, 1997), and northwestern China (Shi et al, 2022). Nevertheless, this type of interdisciplinary investigation has not focused on north-central China, due to the absence of detailed archaeobotanical evidence and accurate dating.…”