Climate stability and low population pressure predict peaceful interactions over 10,000 years of Central Andean history.

Abstract

As anthropogenic climate change threatens to destabilize global societies and ecosystems, anticipating likely human responses becomes ever more urgent. A key global initiative is the promotion of peaceful relations. Nonetheless, studies that systematically evaluate factors that promote peace are limited, and research focuses on recent centuries when climate conditions were stable. Here, we couple evolutionary ecology theory with machine learning models to investigate the relative effects of climatological, demographic, and socio-political conditions on the persistence of peace over the 10,000-year Central Andean Holocene sequence. We find that stable climate conditions and low population density have a strong influence on peace, even when average climate conditions are not ideal for farming. Given that climate projection models predict increasing climate volatility in coming decades, our results suggest that future climate instability may weaken peaceful interactions, particularly among subsistence populations in marginal environments.