The prevalence of infectious disease in a place drives its culture. The idea is known as pathogen stress theory (also known as parasite stress theory). Two of its leading proponents, entomologist and evolutionary biologist Randy Thornhill, and psychologist Corey Fincher, found that people in areas with high pathogen stress tend to show a set of distinct characteristics that people in cooler, dryer latitudes do not.
They tend to be more xenophobic, ethnocentric, and neophobic. They distrust new things, new ideas, and new people, consciously or unconsciously suspecting they are all potential transmitters of disease. They are more nepotistic, favoring those closest to them, more conformist, more likely to support authoritarian rule, more introverted, and more misogynistic.
Thornhill and Fincher have even argued (see chapter 10 in the link above) that immunological advancements in the mid-20th century contributed to the ’60s and ’70s backlash against war, xenophobia, sexism, and racism. In other words, cosmopolitanism and medical science can go hand in hand.
From an evolutionary perspective, this all makes sense. When the threat of infectious disease is high, the costs of being sociable with strangers can outweigh the benefits. When the threat of disease is low, people can feel safer mingling. The problem is, research has found that if people feel like the threat of infectious disease is higher — even if it isn’t — they will start acting like people who live in disease-prone places.
In 2010, psychologist Chad Mortensen led a study in which participants were divided into two groups. One was shown slides depicting pictures and information about germs and infectious diseases. Another was shown photos of conventional-looking buildings. Afterward, they were asked to complete two questionnaires — one a personal inventory aimed at measuring extraversion, agreeableness, conscientiousness, neuroticism, and openness to experience, and another one measuring their perceived vulnerability to disease. Participants who watched the disease slideshow reported being less extraverted, less open-minded toward new people and new experiences, and less cooperative.
As a lover of cities, and a resident of New York, my fear is that even when the threat of the coronavirus passes, the memory will be so vivid that the behavior of New Yorkers will be altered for the foreseeable future.
Social psychologist Julie Huang led another series of experiments during the swine flu epidemic of 2011. In one, she showed a group of participants a story about the health problems associated with the contagion, and the value of vaccination against it, and she showed another group a story unrelated to swine flu. The people who had read the swine flu story reported more prejudice against immigrants — a pattern we’re seeing again now with the surge of anti-Asian sentiment during the coronavirus outbreak. Huang also found that people who had been vaccinated against swine flu actually showed lower levels of prejudice against these strangers, raising the possibility that vaccination can reduce prejudice; that we can be, in a way, inoculated against xenophobia.
In a summary of the research into pathogen threat, Mortensen and colleagues write, “people who are concerned with disease are [also] less likely to have friends with disabilities, tend to dislike obese individuals more, and exhibit more ethnocentric attitudes as well as more xenophobic attitudes toward foreigners who may carry novel diseases or violate local customs.” They add, “Increased disease prevalence was associated with lower levels of extraversion, openness to experience, and in one sample, agreeableness.” (You cannot read these passages and not be reminded that the White House is presently occupied by a world-class germaphobe.)
As a lover of cities, and a resident of New York, my fear is that even when the threat of the coronavirus passes, the memory will be so vivid that the behavior of New Yorkers will be altered for the foreseeable future. A person moves to the city because they love new people, new things, and new ideas. A plague, then, is not just a grave physical injury, but a psychological one, too; spiritual, even. A wound to the soul of the place. That wound will require care as well, in cities all over the world.