Trustworthiness in painted portraits increased over the period 1500–2000 paralleling the decline of interpersonal violence & the rise of democratic values; further analyses suggest association with increased living standards

Tracking historical changes in trustworthiness using machine learning analyses of facial cues in paintings. Lou Safra, Coralie Chevallier, Julie Grèzes & Nicolas Baumard. Nature Communications volume 11, Article number 4728, September 22 2020. https://www.nature.com/articles/s41467-020-18566-7

Abstract: Social trust is linked to a host of positive societal outcomes, including improved economic performance, lower crime rates and more inclusive institutions. Yet, the origins of trust remain elusive, partly because social trust is difficult to document in time. Building on recent advances in social cognition, we design an algorithm to automatically generate trustworthiness evaluations for the facial action units (smile, eye brows, etc.) of European portraits in large historical databases. Our results show that trustworthiness in portraits increased over the period 1500–2000 paralleling the decline of interpersonal violence and the rise of democratic values observed in Western Europe. Further analyses suggest that this rise of trustworthiness displays is associated with increased living standards.