Is intolerance of immigrants an immune system disorder?

A new study proposes that a hyperactive “behavioural immune system” may cause people to shun immigrants, writes Andrew Masterson.

Could anti-immigrant sentiment be motivated by the "behavioural immune system"?
Epoxydude / Getty

Could the immune system be the driving force behind intolerance towards migrants? That’s the contentious theory advanced by political scientists from Aarhus University in Denmark and Temple University in Pennsylvania, US.

The theory, laid out in the journal American Political Science Review, rests on the suggestion that the human body exhibits a “behavioural immune system” – an idea drawn not from biology but psychology.

The concept, laid out a few years ago by Mark Schaller, psychology professor at the University of British Columbia, holds that the immune system has a psychological dimension.

The system, Schaller suggests, is able to detect the possible presence of harmful pathogens – by means of sight or smell – and induce the individual to take defensive actions, such as moving away from the perceived threat.

Schaller suggests that the behavioural immune system is a largely unacknowledged driver of human sociability, prejudice and sexual behavior.

It is not a theory that enjoys wide support in the broader evolutionary, medical or immunological communities, but it might – contend the authors of the new study – explain the frequent and irrational rejection of migrants by resident communities.

Political scientists Lene Aarøe and Michael Bang Petersen, from Denmark, and Kevin Arceneaux, present a meta-analysis of earlier studies into anti-migrant sentiment along with new studies of Americans and Danes and compare the results to what they term “disgust sensitivity” – the posited pre-conscious warning signals of the behavioural immune system.

The effects of disgust sensitivity on contact with immigrants compared to political ideology, income and education.
American Political Science Review

Disgust sensitivity readings turned out to be much stronger predictors of contact with migrants than education, income or ideology.

Aarøe and colleagues suggest that people with very active behavioural immune systems are “hypersensitive” and on a non-conscious level regard migrants as a disease hazard on a par with blood, rot and excrement.

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

The key result of this hypersensitivity, the researchers suggest, is avoidance. This counteracts the process of contact between residents and migrants, which has been shown to decrease hostility towards newcomers.

The findings, the researchers conclude in their paper, provide “an explanation for why peaceful integration and interaction between ethnic majority and minorities is so hard to achieve.”

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Andrew Masterson is news editor of Cosmos.
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