The evolution of disgust for pathogen detection and avoidance

Jessica K Hlay,Debra Lieberman,Carolyn R Hodges-Simeon,Steven Arnocky,Graham Albert,George Richardson,Caitlyn Placek,Carlota Batres

doi:10.1038/s41598-021-91712-3

Abstract

The behavioral immune system posits that disgust functions to protect animals from pathogen exposure. Therefore, cues of pathogen risk should be a primary driver influencing variation in disgust. Yet, to our knowledge, neither the relationship between current pathogen risk and disgust, nor the correlation between objective and perceived pathogen risk have been addressed using ecologically valid measures in a global sample. The current article reports two studies addressing these gaps. In Study 1, we include a global sample (n = 361) and tested the influence of both perceived pathogen exposure and an objective measure of pathogen risk—local communicable infectious disease mortality rates—on individual differences in pathogen and sexual disgust sensitivities. In Study 2, we first replicate Study 1’s analyses in another large sample (n = 821), targeting four countries (US, Italy, Brazil, and India); we then replaced objective and perceived pathogen risk with variables specific to the SARS-CoV-2 pandemic. In Study 1, both local infection mortality rates and perceived infection exposure predicted unique variance in pathogen and sexual disgust. In Study 2, we found that perceived infection exposure positively predicted sexual disgust, as predicted. When substituting perceived and objective SARS-CoV-2 risk in our models, perceived risk of contracting SARS-CoV-2 positively predicted pathogen and sexual disgust, and state case rates negatively predicted pathogen disgust. Further, in both studies, objective measures of risk (i.e., local infection mortality and SARS-CoV-2 rates) positively correlated with subjective measures of risk (i.e., perceived infection exposure and perceived SARS-CoV-2 risk). Ultimately, these results provide two pieces of foundational evidence for the behavioral immune system: 1) perceptions of pathogen risk accurately assay local, objective mortality risk across countries, and 2) both perceived and objective pathogen risk explain variance in disgust levels.

Highlights

The behavioral immune system posits that disgust functions to protect animals from pathogen exposure
This study was approved by the Boston University Institutional Review Board (IRB); all protocols were followed in accordance with the IRB and participants gave informed consent
India was significantly higher than the US in sexual disgust [t(218) = 4.01, d = 0.55, p < 0.01] and perceived infection exposure [t(218) = 5.60, d = 0.75, p < 0.01]

Summary

Introduction

The behavioral immune system posits that disgust functions to protect animals from pathogen exposure. The mouth and genitals likewise serve as portals of contamination For this reason, researchers have proposed that disgust functions to regulate consumption and contact behaviors of individuals, thereby mitigating risks of pathogen infection (e.g. 11,12). Skolnick and Dzokoto[22] found that in Ghana, which has a higher IDP, participants had higher pathogen and moral disgust levels than in the US, which has a lower IDP; sexual disgust was not examined in this study This evidence supports elements of the BIS, demonstrating that those in an environment with a higher pathogen load perceive themselves to be more vulnerable to disease and react with more psychological aversion to pathogen cues. Causal inference is not warranted in the context of a comparison of only two countries, because it is not possible to control any potential confounders that vary between countries along with parasite stress and disgust

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