We find that national parasite stress and individual disgust sensitivity relate more strongly to adherence to traditional norms than they relate to support for barriers between social groups. These results suggest that the relationship between pathogens and politics reflects intragroup motivations more than intergroup motivations.
National parasite stress relates to traditionalism (an aspect of conservatism especially related to adherence to group norms) but not to social dominance orientation (SDO; an aspect of conservatism especially related to endorsements of intergroup barriers and negativity toward ethnic and racial outgroups). Further, individual differences in pathogen-avoidance motives (i.e., disgust sensitivity) relate more strongly to traditionalism than to SDO within the 30 nations.
The costs imposed by pathogens on their hosts have spurred the evolution of complex antipathogen defenses, many of which are behavioral. In humans, such defenses range from the proximate avoidance of pathogen cues to the execution of complex rituals, often with far-reaching consequences. At the individual level, functionally specialized psychological mechanisms detect pathogen cues and motivate avoidance of physical contact with pathogens [e.g., via the emotion of disgust]. These mechanisms, which have been collectively referred to as the behavioral immune system, influence, among other things, mate preferences, dietary preferences, and person perception. At the cultural level, many rules and rituals putatively function to mitigate infection risk, including those concerning food preparation and consumption, coughing and sneezing, and the use of a particular hand in ablutions (and little else).
Some of the most provocative findings in the behavioral immune system literature suggest that political attitudes are influenced both by individual motivations to avoid pathogens and by the presence of pathogens within an ecology. At the individual level, the degree to which people are disgusted by pathogen cues and wary of infection-risky situations relates to a number of politically relevant variables, including political party preference, openness to experience, and collectivism.
At the cultural level, nations with greater infectious disease burdens (i.e., parasite stress) are governed by more authoritarian regimes and are more religious, more collectivistic, and less open to experience, all of which are hallmarks of conservative ideology.