Cultures with high pathogen levels exhibit norms, values, and behaviors that reduce the spread of disease. This paper examined whether these patterns would be evident in a modernized country, the United States, where mortality from infectious diseases tends to be low. Specifically, this research tested whether the incidence of common infections (e.g., Chlamydia, hepatitis, tuberculosis) was related to individualism/collectivism at the state level. Collectivism, which entails restricted social networks and a wariness of unfamiliar people and places, should be adaptive where infectious diseases are pervasive; individualism, which entails larger social networks and greater trust toward unfamiliar people, should cost less when communicable diseases are not a concern. Consistent with these hypotheses, infection rates strongly predicted collectivistic behavior patterns—such as living with extended family, carpooling to work, a lower divorce-to-marriage ratio—across states. This pattern also held within regions of the country. The results suggest that even in modernized cultures, pathogens influence how people approach relationships and structure their environment.
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