Evolutionary, ontogenetic, and environmental origins of human pathogen disgust sensitivity
Embargo Date
2026-04-07
OA Version
Citation
Abstract
Throughout evolution, humans have faced the ever-present threat of pathogenic infection. It has been proposed that the behavioral immune system evolved to reduce the costs of infection by triggering pathogen disgust in response to probabilistic pathogen cues and motivating pathogen avoidance. It has been proposed that individuals should vary in their sensitivity to potential pathogen cues (pathogen disgust sensitivity; PDS) depending on context, such as the risks and resources in a given environment and individual vulnerability. In this project, I use both internationally-validated and locally created surveys to measure individual differences in PDS. I then evaluate variables that may influence PDS, such as age, sex, health, and local disease risk, and assess how PDS may impact health-protective behaviors. After reviewing the literature on pathogen avoidance in Chapter 1, I present data from three studies that focus on possible input variables that may impact variation in PDS. In Chapter 2, I examine sex- and age-related differences in PDS in two independent groups: pre-adults living on the island of Utila, Honduras, and an international online adult sample. Results demonstrate that PDS increases throughout childhood, then stabilizes in adulthood, as predicted. Additionally, women report higher PDS in adulthood, but not childhood. In Chapter 3, I assess the relationship between individual health and PDS. I found that those who perceived themselves as more vulnerable to infection and those with decreased mucosal immunity had higher PDS. In Chapter 4, I analyze the relationship between PDS and perceived and objective disease risk. Across four countries, I found that both perceived and objective communicable disease mortality risk positively predict PDS. In Chapter 5, I examine the relationship between PDS and attitudes, desires, and behaviors towards casual sex. Opposite of my predictions, I found that those who report higher PDS report more favorable attitudes towards and more engagement in casual sex. In Chapter 6, I discuss how my overall findings demonstrate that PDS varies based on sex, age, local disease threat and perceived infection vulnerability. I also discuss several unexpected findings and suggest pathways for future research to explore these results.
Description
2024