Cepon-Robins: A healthy sense of disgust can keep you from getting sick

Coauthors Tara Cepon-Robins, assistant professor of anthropology at the University of Colorado Colorado Springs, and Theresa Gildner, assistant professor of biological anthropology at Washington University in Saint Louis, prepare stool samples for parasite and microbiome analysis. Photo credit: Melissa Liebert, Northern Arizona University.

Remember the last time you felt nauseous, revolted or generally repulsed? New research from Tara Cepon-Robins, assistant professor of anthropology, suggests that same feeling – disgust – could be your body’s way of keeping you from getting sick.

Cepon-Robins was the lead researcher on the study, “Pathogen disgust sensitivity protects against infection in a high pathogen environment,” published by the Proceedings of the National Academy of Sciences February 2021.

The research is the first in its field to directly test whether individuals who experience a greater pathogen disgust sensitivity – that is, people who are more sensitive to feeling disgust – will become exposed to fewer pathogens in their local environments, and thus suffer fewer infections.

“Darwin first recognized disgust as an evolved human emotion, hypothesizing that it aided in avoidance or expulsion of ‘tainted’ food,” Cepon-Robins and fellow researchers write in the study.

“Since then, many studies have supported the hypothesis that disgust is a universal human emotional response that evolved to motivate avoidance of certain kinds of fitness-reducing substances. [Yet] evidence has been largely indirect, [and] no studies have directly tested whether greater pathogen disgust sensitivity is associated with fewer current infections.”

An Upano Valley community showing variation in housing styles. The Upano Valley is the more market integrated region examined in the study compared to the more remote Cross Cutucú region.

Researchers examined data from households in three indigenous Ecuadorian Shuar communities, all located in high-pathogen environments but with differing levels of economic development.

The study hypothesized that in environments where disgust-motivated avoidance of contaminated food and other pathogen-containing substances has a low cost – for example, in areas with reliably clean water and cooking surfaces that are easily cleaned – individuals likely experience greater pathogen disgust.

But in environments where individuals must regularly encounter potential pathogens to acquire food or shelter – for example, among populations who often have direct exposure to soil, animal feces, dirt floors or potentially-contaminated water sources – disgust-motivated avoidance becomes more costly.

Their findings support the hypothesis that disgust is an evolved human emotion that functions as a disease-avoidance mechanism, helping humans to reduce their exposure to pathogens. In addition, the findings demonstrate that the human disgust response is calibrated to the local costs and benefits of avoidance and infection.

Significantly, it is the first study to document that higher pathogen disgust sensitivity is associated with lower levels of pathogen infection among an indigenous subsistence-based population living in a high-pathogen environment – conditions that are, in important ways, more similar to those experienced throughout human evolutionary history than those tested to date.

The study was conducted as part of the Shuar Health and Life History Project and includes researchers from Washington State University, Washington University in St. Louis, Northern Arizona University, Baylor University, University of Oregon and Queens College, City University of New York.

Cepon-Robins writes, researches and teaches in the Department of Anthropology in the College of Letters, Arts and Sciences, which enrolls 5,800 students among 21 departments and programs. The college offers 19 majors and 53 minors in the arts, humanities, social sciences and natural sciences. Learn more about Cepon-Robins’ work.