Olfaction-mediated behavioural defence mechanisms in humans

This thesis consists of two parts. The first part introduces the importance of behavioural defence mechanisms, specifically the behavioural immune system and mainly in humans. I review current knowledge regarding behavioural defence mediated by odour cues. Although behavioural defence mechanisms are important for all individuals who live in social groups, I focus on mate choice, because that is the context in which olfaction-mediated behavioural defence is studied the most. Subsequently, the importance of olfaction is demonstrated using the example of self-inspection and I discuss how the behavioural immune system may be intertwined with this relatively understudied behaviour. Finally, last chapter deals with associations between olfaction and other modalities that play a role in the detection of cues which help select a healthy and immunocompetent partner. In the second part of the thesis, I present nine papers: three reviews and six empirical studies. The review papers summarise the functioning of the behavioural immune system, olfaction- mediated pathogen avoidance in mammals, and the merely weak association between attractiveness ratings based on different modalities. The first empirical paper investigates whether the threat caused by the Covid-19 pandemic led to increased perceived disgust,..