The researchers, using principal component analysis, generalized additive models across 12 agriculture origin locations, and a model predicting hunter-gatherer population density, evaluate hindcasted population density trends to suggest predictors of the development of agriculture. Using domestication as an indicator of agriculture, they test 3 competing hypotheses regarding agriculture development. Their results are consistent with the "surplus" hypothesis, indicating that agriculture arose as population densities increased along with environmental capabilities.

Jared Diamond previously argued that the East-West orientation of Eurasia allowed for the spread of substantial cultural, political, technological, and military innovations, due to environmental homogeneity across the continent. The authors of this article test this theory through quantitative analyses. Their results suggest that ecology can indeed influence the potential for cultural transmission, consistent with Diamond's theory. However, the authors do not find support for Eurasia having lower environmental barriers to cultural transmission in comparison to other continents.