Roma Eterna? Roman rule explains regional well-being divides in Germany

• We study how history can shape present-day psychological outcomes across Germany. • For psychological outcomes, we focus on well-being and adaptive personality traits. • Roman rule around 2,000 years ago predicts regional differences in these outcomes. • Roman investments in advanced economic institutions might explain this effect. • The results illustrate how ancient cultures can imprint a macro-psychological legacy. In light of persistent regional inequalities in adaptive outcomes such as health, wellbeing, and related personality traits, psychological research is increasingly adopting a historical perspective to understand the deeper roots of these patterns. In this study, we examine the role of ancient cultures, specifically the impact of Roman civilization around two thousand years ago, on the macro-psychological character of German regions. We compare present-day regions that were advanced by Roman culture with those that remained outside of Roman influence. Even when accounting for more recent historical factors, we find that regions developed by Roman civilization show more adaptive personality patterns (Big Five) and better health and psychological wellbeing today. Results from a spatial regression discontinuity design indicate a significant effect of the Roman border on present-day regional variation in these outcomes. Additional analyses suggest that Roman investments in economic institutions (e.g., trade infrastructure such as Roman roads, markets, and mines) were crucial in creating this long-term effect. Together, these results demonstrate how ancient cultures can imprint a macro-psychological legacy that contributes to presentday regional inequalities.