Name Uniqueness and Individualism in France: A century of changes across 95 prefectures

Individualism, the prioritization of personal distinctiveness over group conformity, is theorized to increase with economic development. This study tests this hypothesis over a century (1900–2022) across 95 French départements, using name uniqueness as a behavioral proxy. We first validate this proxy at the subnational level, showing that name uniqueness correlates with regional survey-based individualism indices (World Values Survey), even after controlling for immigration rates. Using complete civil registry data (N ≈ 79 million) and a bootstrapped name uniqueness score, we then analyze its relationship with economic development across space and time. Our analysis yields three key findings. First, longitudinal analysis reveals a strong positive association: as GDP per capita increased nationally over the 100-year period, name uniqueness rose significantly across all départements. Second, after removing shared temporal trends by standardizing variables within each year, effectively treating départements (n = `r nobs(norm_model_boy)`) as small, culturally and socially identical countries, GDP per capita continues to predict higher name uniqueness. Third, we uncover nuanced patterns: the relationship was moderated by gender, particularly during the World Wars, and rising economic inequality between regions was accompanied by growing divergence in naming practices, suggesting that development drives both cultural individualism and cultural stratification. Together, these results provide robust, fine-grained evidence that economic development fosters a cultural shift toward greater individualism.