Prejudices have plausibly existed since the origins of humanity. In an evolutionary sense, prejudices might have solved an adaptive problem.
In a study by Huang and colleagues (2011), the authors examined the link between disease-avoidance behavior and prejudices. They examined how disease-protection behaviors such as vaccination and hand washing would influence prejudices against out-groups.
They found that:
- The presence of disease-related cues were associated with an increase in prejudices
- Perceptions of disease immunity (hand washing/vaccination) could diminish prejudices
What do these findings tell us? The authors suggest that we have evolved a “behavioral immune system” that has helped us avoid disease-related threats.
For this reason, we are sensitive to cues that are associated with the presence of diseases. These cues may produce negative evaluations such as prejudices toward the possible disease carrier(s).
The cues are actively evaluated. Since the evaluation of possibly contagious cues is based on subjective evaluations, the evaluation may be wrong, meaning that behavioral disease-avoidance may occur without the presence of an actual threat. This is why people hold prejudices.
It is too costly not to prejudge a possible disease carrier since it is a possible threat to one’s physical health. It is simply a behavioral mechanism that has evolved to defect threats as early as possible by making prejudices toward the possible disease carrier(s).
For example, people who believe they are more vulnerable to disease than others have been shown to possess more pronounced attitudes toward unfamiliar social groups such as immigrants and gay males.
A study of women has also shown that women have more ethnocentric or xenophobic attitudes during the stage of pregnancy where the fetus is most vulnerable to disease.