Rarely has the threat of disease occupied so much of our thinking. For weeks, almost every newspaper has stories about the coronavirus pandemic on its front page; radio and TV programmes have back-to-back coverage on the latest death tolls; and depending on who you follow, social media platforms are filled with frightening statistics, practical advice or gallows humour.

As others have already reported, this constant bombardment can result in heightened anxiety, with immediate effects on our mental health. But the constant feeling of threat may have other, more insidious, effects on our psychology. Due to some deeply evolved responses to disease, fears of contagion lead us to become more conformist and tribalistic, and less accepting of eccentricity. Our moral judgements become harsher and our social attitudes more conservative when considering issues such as immigration or sexual freedom and equality. Daily reminders of disease may even sway our political affiliations.

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The recent reports of increased xenophobia and racism may already be the first sign of this, but if the predictions of the scientific research are correct, they may reflect much deeper social and psychological shifts.

The behavioural immune system

Like much of human psychology, these responses to disease need to be understood in the context of prehistory. Before the birth of modern medicine, infectious disease would have been one of the biggest threats to our survival. The immune system has some amazing mechanisms to hunt and kill those pathogenic invaders. Unfortunately, these reactions leave us feeling sleepy and lethargic – meaning that our sickly ancestors would have been unable to undertake essential activities, like hunting, gathering or childrearing.