This study undertakes a systematic exploration of the relationship between ecological conditions and human cultural variation, responding to the research question: “How much of cultural variation can be explained by ecology?”. The authors use a dataset comprising 9 ecological variables: rainfall, temperature, GDP, the Gini index of resource inequality, extrinsic mortality, life expectancy, disease threat, unemployment and population density. They assess the relation between these 9 variables and 66 cultural variables across 201 countries. In addition, the study considers the effects of spatial and cultural autocorrelation, including 11 distinct statistical metrics. The results are consistent with the idea that ecological variables make a substantial contribution to human cultural variation, and particularly multiple ecological variables simultaneously. Current levels and average levels of ecological conditions emerge as particularly influential. Conversely, markers of ecological variability and unpredictability demonstrate more relatively little influence.