Pathogen prevalence is associated with cultural changes in gender equality

Gender equality has varied across time, with dramatic shifts in countries such as the United States in the past several decades. Although differences across societies and changes within societies in gender equality have been well documented, the causes of these changes remain poorly understood. Scholars have posited that such shifts have been driven by specific events (such as Title IX and Roe versus Wade), broader social movements (such as feminism and women's liberation) or general levels of social development (for example, modernization theory 1). Although these factors are likely to have been partly responsible for temporal variations in gender equality, they provide fairly intermediate explanations void of a comprehensive framework. Here, we use an ecological framework to explore the role of key ecological dimensions on change in gender equality over time. We focus on four key types of ecological threats/affordances that have previously been linked to cultural variations in human behaviour as potential explanations for cultural change in gender equality: Infectious disease, resource scarcity, warfare and climatic stress. We show that decreases in pathogen prevalence in the United States over six decades (1951-2013) are linked to reductions in gender inequality and that such shifts in rates of infectious disease precede shifts in gender inequality. Results were robust, holding when we controlled for other ecological dimensions and for collectivism and conservative ideological identification (indicators of more broadly traditional cultural norms and attitudes). Furthermore, the effects were partially mediated by reduced teenage birth rates (a sign that people are adopting slower life history strategies), suggesting that life history strategies statistically account for the relationship between pathogen prevalence and gender inequality over time. Finally, we replicated our key effects in a different society, using comparable data from the United Kingdom over a period of seven decades (1945-2014).