A number of studies have shown that political and personal beliefs can be related to health behaviors. For example, political orientation may be affected by a person’s beliefs about community, self-reliance, and morality, and these same beliefs may influence that person's likelihood of seeking treatment for a potentially stigmatizing condition, such as a mental or a sexual health issue. A recent article published in PNAS expands on past findings, suggesting that individual traditionalism is associated with national parasite stress.

The study recruited participants from 30 countries, with at least 200 people enrolled per country. These participants completed a short questionnaire describing their attitudes toward political issues and groups of people.

This questionnaire was intended to probe participants’ attitudes on three things: traditionalism, social dominance, and sensitivity to feelings of disgust. Traditionalism was assessed in terms of adherence to old-fashioned values, a family focus, and religiosity. Social dominance orientation was assessed in terms of how much participants favored inter-group equality. Finally, disgust sensitivity was assessed in terms of responses to various situations such as “stepping on dog poop.”

The authors then aggregated these individual-level responses and probed their relationship to parasite stress, which was defined through estimates of the historical prevalence of parasites within the national populations.

The most striking portion of the study’s results showed that individuals in nations with higher parasite stress were more traditional. This relationship had a strong correlation (r=0.70, p<0.001), but of course that doesn't demonstrate causality between parasite prevalence and traditionalism. The authors did not find a significant relationship between parasite stress and social dominance orientation (i.e. beliefs about intergroup equality), nor did they uncover a link between disgust sensitivity and parasite stress. The latter might have made sense, in that strong feelings of disgust might help people avoid situations where they're more likely to pick up parasites.

Based on these results, the authors suggest that people who are particularly motivated to avoid pathogens may also find traditional rules and rituals appealing. For example, people who are particularly averse to contracting sexually transmitted infections may be more inclined to adhere to more traditional values regarding sexual behaviors. While that's not a direct connection, it's possible that aversion to pathogens may have influenced the development of traditional value systems.

In addition, traditional food preparation techniques typically include ingredients with antimicrobial properties, and traditional hygiene rules regarding food handing tend to limit exposure to pathogens. People who follow these traditions may be more likely to influence the food behavior of others so that this behavior spreads and pathogen exposure is widely reduced.

As these two examples demonstrate, the relationship between pathogen avoidance and traditional values suggested by this study could either reflect an individual’s motivation to regulate their own exposure to pathogens or could reflect an individual’s influence on the behavior of others.

Right now, any causal pathways between traditionalism, pathogen exposure, pathogen aversion, and parasite stress are unclear. Future research in this field may clarify which of these came first: pathogen aversion, traditional values, or problems with high rates of infection.

PNAS, 2016. DOI: 10.1073/pnas.1607398113 (About DOIs).