The immune system may explain skepticism towards immigrants

There are deep-seated conflicts throughout the Western world about how to handle the influx of refugees and immigrants–should we close our borders or bid the newcomers welcome? New research reveals that such opposing points of view are grounded in more than deliberate thought and reasoned arguments. At the level of preconscious processing, strong feelings about immigrants are controlled by something as surprising as the immune system.

“The research results provide new understanding of why society does not absorb the new arrivals and why integration fails,” says Aarhus University Associate Professor Lene Aarøe. “Those who are very concerned about the risk of infection are those who are most reluctant to seek out social contact with immigrants–something that we otherwise know fosters tolerance.”

“We haven’t just found a small, peculiar correlation, but something that can block the integration of immigrants,” continues Professor Michael Bang Petersen.

The two political scientists from Aarhus BSS at Aarhus University, Denmark, have collaborated with Professor Kevin Arceneaux, Temple University, on the study, which has just been published in American Political Science Review, the leading journal for political science research.

Deeply rooted reaction

Throughout evolutionary history, our ancestors fought pathogens. The physical immune system evolved to defend us when such pathogens entered the body. Concurrently, humans and other animals have evolved a behavioral immune system, which motivates us to avoid situations where we might become exposed to infection. Avoiding potential sources of infection, such as excrement, blood and rot, has been crucial to our survival, and the motivation to avoid infection remains deeply rooted in us to this day.

The behavioral immune system cannot be controlled. It works on a subconscious level and is particularly sensitive in some people. According to the research team, such people’s immune systems overreact and subconsciously misinterpret everything that is different as potential sources of infection.

“People with birthmarks, physical disabilities, abnormalities and something as innocent as a different skin color are subconsciously considered disease carriers by the hypersensitive,” says Michael Bang Petersen.

Better safe than sorry

It is important that these research results are not misunderstood: People with a hypersensitive behavioral immune system do not avoid immigrants because they are consciously afraid of becoming ill if they interact with them. Immigrants are not a source of infection. It is on the subconscious level that the immune system misinterprets differences as a potential sign of infection–the consequence being that hypersensitive individuals avoid interaction with immigrants.

“The behavioral immune system functions according to a ‘better safe than sorry’ approach,” explains Michael Bang Petersen.

This has consequences for integration and tolerance. One of the primary methods for achieving integration and tolerance is in the contact between immigrants and the majority population. But if immigrants are mistakenly interpreted as an infection hazard, contact becomes something to be avoided; if you are hypersensitive to infection, the last thing you want to do is to interact with a pathogen source.

The research also shows that hypersensitive people are completely indifferent to any good intentions that immigrants might have to contribute to society. The fear among the hypersensitive is due to the perceived risk of infection–immigrants’ intentions are inconsequential. Thus, another of the primary paths to integration is blocked.

Why is the conflict so persistent?

“Our research provides new perspectives on why the immigrant question creates such deep-seated and emotion-laden conflicts in Western society. It is partly shaped by these psychological differences so deeply rooted in us,” says Lene Aarøe.

The research focuses on why it is difficult to arrive at an understanding of each other’s points of view when one party does not have a hypersensitive behavioral immune system and does not see the same risks in immigrants.

“If some people see dangers in immigrants that others don’t, it’s difficult to reach a mutual understanding with reason-based, rational arguments. The fear comes from deeply ingrained unconscious systems that we can’t control. You can discuss whether immigrants are a financial gain or burden to society, whether to close the borders or bid the immigrants welcome, but if people are concerned about an entirely different risk–and perhaps one they aren’t even fully aware of–it’s difficult to achieve a mutual understanding of what is the right policy,” says Michael Bang Petersen.

The coupling between immigrants and the risk of infection is a misperception, so a greater awareness of why we have different response patterns might contribute to a better understanding among population groups and thereby to integration.


  • The research is published in the article “The Behavioral Immune System Shapes Political Intuitions: Why and How Individual Differences in Disgust Sensitivity Underlie Opposition to Immigration” in the prestigious journal American Political Science Review: https://doi.org/10.1017/S0003055416000770
  • The study is the first comparative study of the degrees of concern among Danes and Americans for infection and their respective political attitudes towards immigrants.
  • The study includes lab experiments in which the subjects’ levels of perspiration were measured while being presented with pictures related to the risk of infection and disease.
  • Additionally, several thousand respondents participated in representative surveys that took into account the conventional explanatory factors such as gender, age, education, income, political ideology and race, as well as whether they are generally prone to be anxious.
  • The results show that the fear of infection has an impact on attitudes towards immigrants that is at least as strong as education and more so than income.

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7 thoughts on “The immune system may explain skepticism towards immigrants”

  1. “The coupling between immigrants and the risk of infection is a misperception”. This unsupported assumption leads to questionable conclusions. Fear of disease from immigrants may not be unreasonable. Indeed, there are many examples of diseases like TB where most cases are immigrants. This is not surprising as diseases like TB are common in some countries. Addressing fear of infection through medical screening would help reduce fear of immigrants. Lack of any screening of illegal immigrants explains why illegal immigrants are feared more than legal immigrants.

  2. Unconscious avoidance of danger explains why so many are racist out of fear. For example so called hate sites like Storm Front. Read the postings there and most are about reasons to fear immigrants. Even expressions of hate trace back to fear. Of course it doesn’t help when unconscious fear is validated by news reports.

  3. karen, I dont know if what you told is a joke, but if not I explain you what I understood: in people who fear immigrants, the immune system is differently activated.

  4. I also believe that in group and outgroup problems are quite important today, possibly being intolerant to an outgroup may be brought both by genetic factors and by infections.
    I believe lot of mental illness like schizophrenia and autism to be brought by infections and genetic factor , it could be the same for intolerant people.

    • Interesting delema, should intolerace be treated as mental illness instead of being condemned as hate? Should those with no fear of immigrants be considered mentally ill as they lack normal fear reaction? What defines illness? Is it normal unconscious behavior (intolerance) or what society demands at this time (tolerance)? Seems to me that human evolution is in conflict with some of societies demands.

  5. Just the idea of an immigrant recruits the immune system, or face to face contact?

    • I believe it is either from my take on article. Similar to the reaction of fear when a person’s behavior is very odd. Fear of any potential danger is normal human reaction as this and other studies show. Makes sense that we would evolve that way.

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