Van Lange et al. argue that variations in climate explain cross-societal variations in violence. We suggest that any approach seeking to understand cross-cultural variation in human behavior via an ecological framework must consider a wider array of ecological variables, and we find that income inequality and sex ratio are better predictors than climate of cross-societal variations in violence.

Why has fiction been so successful over time? We make the case that fiction may have properties that enhance both individual and group-level fitness by (a) allowing risk-free simulation of important scenarios, (b) effectively transmitting solutions to common problems, and (c) enhancing group cohesion through shared consumption of fictive worlds.

We propose that grounded procedures may help explain psychological variations across cultures. Here we offer a set of novel predictions based on the interplay between the social and physical ecology, chronic sensorimotor experience, and cultural norms.

Baumard proposes a model to explain the dramatic rise in innovation that occurred during the Industrial Revolution, whereby rising living standards led to slower life history strategies, which, in turn, fostered innovation. We test his model explicitly using time series data, finding limited support for these proposed linkages. Instead, we find evidence that rising living standards appear to have a time-lagged bidirectional relationship with increasing innovation.