Implications of the behavioural immune system for social behaviour and human health in the modern world

Abstract

The 'behavioural immune system' is composed of mechanisms that evolved as a means of facilitating behaviours that minimized infection risk and enhanced fitness. Recent empirical research on human populations suggests that these mechanisms have unique consequences for many aspects of human sociality--including sexual attitudes, gregariousness, xenophobia, conformity to majority opinion and conservative sociopolitical attitudes. Throughout much of human evolutionary history, these consequences may have had beneficial health implications; but health implications in modern human societies remain unclear. This article summarizes pertinent ways in which modern human societies are similar to and different from the ecologies within which the behavioural immune system evolved. By attending to these similarities and differences, we identify a set of plausible implications-both positive and negative-that the behavioural immune system may have on health outcomes in contemporary human contexts. We discuss both individual-level infection risk and population-level epidemiological outcomes. We also discuss a variety of additional implications, including compliance with public health policies, the adoption of novel therapeutic interventions and actual immunological functioning. Research on the behavioural immune system, and its implications in contemporary human societies, can provide unique insights into relationships between fitness, sociality and health.

Keywords: behavioural immune system; conformity; health; infection; sociality; xenophobia.

Figure 1.

Results from an experiment testing the effect that the psychological salience of infectious diseases has on xenophobia [31]. Canadian participants first watched a brief slide show. In one experimental condition, the content of the slide show made salient the threat posed specifically by infectious diseases; in a control condition, the slide show made salient other life-threatening dangers (e.g. electrocution). After the slide show, participants indicated preferences for the allocation of government funds to recruit immigrants from various countries, some of which were subjectively familiar (e.g. Poland, Taiwan) and some that were subjectively foreign (e.g. Mongolia, Peru). Xenophobia is indicated by a relative preference to recruit familiar immigrants rather than foreign immigrants. Results revealed that when the threat posed by infectious diseases was temporarily salient, people exhibited more strongly xenophobic attitudes.

Figure 2.

Results from an experiment testing the effect that the psychological salience of infectious diseases has on conformity to majority opinion [14]. Participants first engaged in a recall task in which they recalled and described events from their own lives. In one condition, they recalled events that made them feel vulnerable to infectious diseases; in another condition, they recalled events that made them feel vulnerable to other dangers; in a third condition they recalled non-threating events. Afterwards, they engaged in a behavioural decision-making task that assessed conformity to majority opinion. Results revealed that when their vulnerability to infectious diseases was temporarily salient, an especially high percentage of people conformed to majority opinion.