THE EFFECTS OF PARASITES ON HUMAN BEHAVIOUR: AN EVOLUTIONARY PERSPECTIVE

Parasites and predators possess serious threats to humans throughout our evolutionary history. Although the impact of predators in modern world is lower than previously, parasites still influence morbidity and mortality of contemporary humans. From the evolutionary perspective, selective pressures caused by parasites should favour individuals that successfully avoid objects/subjects which transmit parasitic diseases and/or those who are successful in combats with them. There is growing evidence for the existence of evolved anti-parasite behaviours in animals, beginning with invertebrates and ending with primates. Avoidance of infected individuals, grooming and self-medication are most common behavioural strategies that are believed to reduce the transmission of parasites. Here we review recent evidence suggesting that several behavioural and emotional traits in humans evolved as a response to selective pressure caused by parasites. Disgust sensitivity and pathogen threat may be a mechanism that generates both a cross-cultural variation in preferences for certain facial traits, as well as drivers of religious diversity, political stability of countries, parenting cognitive abilities and prevalence of extraversion and openness to new ideas. Finally, we declare areas for a future research based on questions guided by the evolutionary perspective.