Parasites On the Mind

There are two things I really like to learn about: parasites and the human mind. And so I was intrigued to learn about some studies that suggest that we defend ourselves from infections not only with an immune system made up of cells and antibodies, but one made up of unconscious behaviors. It’s the topic of my new column about the brain in Discover. Other people can make us sick, and so perhaps we deal with them differently depending on our risk of getting sick. Take this study, from Carlos Navarrete, a psychologist at Michigan State University. He and his colleagues designed an experiment to compare how pregnant women respond to strangers. During the first trimester, both mother and child are particularly vulnerable to infection.

Navarrete and his colleagues had 206 pregnant women read two essays that were written, they were told, by students. One of the essays was by a foreigner who criticized the United States, the other by an American who praised the country. The women then had to rate the essayists for their likability, intelligence, and other qualities. Women in the first trimester were more likely than those in the second or third trimester to give a high score to the American and a low score to the foreigner. The pregnant women’s vulnerability to infection, Navar­rete concludes, brought with it a heightened disapproval of foreigners.

You can read the whole thing here.