The Gender-Equality Paradox in Height: A Cross-National Test of the Evolutionary-Informed Model

ABSTRACT The gender-equality paradox describes a surprising and counterintuitive pattern whereby, in countries with higher levels of gender equality and socioeconomic development, differences between men and women become more pronounced rather than diminished. While this phenomenon has been widely documented in psychological and behavioral domains, recent evidence suggests that it may also extend to physiological traits such as height. However, existing evidence is limited either to cross-sectional studies on 69 countries or a longitudinal study in a single national context, neither of which fully tests key predictions of the evolutionary-informed model. The present study provides a cross-national longitudinal test of this model’s predictions using data on adult height covering over 200 countries and 101 birth cohorts from 1896 to 1996. Using multilevel generalized additive models, the study tests three directional predictions: whether changes in height occur in the same direction for both sexes, whether increases are greater among males than females, and whether decreases are greater among males than females. By testing these predictions across countries and over time, the study provides a direct evaluation of the evolutionary-informed model and distinguishes between competing explanations for the gender-equality paradox.