This trade-off between wanting to reproduce and wanting to avoid bodily secretions presents an interesting challenge for evolution and has resulted in a complex relationship between being turned-on and grossed-out.
Accordingly, disgust is associated with nausea and vomiting. This all makes intuitive sense, but seems to be missing a large piece of the puzzle. Toxic and foul tasting substances can elicit disgust responses, but we also commonly experience disgust as a reaction to sexual transgressions and immoral behaviour, as well as responding to tactile experiences like coming into contact with dog poo.
This stems from the fact that our emotions are powerful behavioural motivators that likely evolved as a response to specific and pervasive adaptive problems in our ancestral environment.
Based on this approach, disgust is considered to have a number of distinct domains including pathogen and sexual components. A vast body of academic research acknowledges pathogen disgust as an effective motivator of avoiding potential sources of infection. Pathogen disgust likely evolved as a result of the tremendous pressure that was placed on survival, and indeed reproduction, by disease. Infectious microbes have been a consistent source of danger for hominids, and continue to be today, especially for those in developing nations.
Pathogen disgust thus functions as a behavioural immune system, motivating the organism to avoid contact with potential disease vectors that would necessitate a physiological immune response.
Sexual intercourse, while necessary and fun , also carries a huge risk of exposure to potential pathogens, including some particularly nasty bugs in addition to the usual gamut of infections passed from person to person.
Say, our close genetic relatives. Inbreeding increases the likelihood of harmful recessive diseases—an obvious handicap to any organism. The thought alone of engaging in intercourse with a sibling or parent is pretty distressing, and is likely a result of our evolved capacity for sexual disgust to discourage this very behaviour.
According to Tybur, Lieberman, and Griskevicius , sexual disgust may also have evolved to motivate the avoidance of other costly sexual behaviours like investing time, effort and resources into acquiring poor mates i. It seems as though we should be constantly grossed out by the risk of contracting horrible diseases, or even worse, horrible babies from everybody we meet. The females who had watched erotic videos rated sex-related stimuli as less disgusting and performed more of the disgusting behavioural tasks.
Sexual arousal actually resulted in the down-regulation of disgust in preparation for intercourse. This study also confirms that disgust and arousal are antithetical physiological and psychological experiences and when it comes to choosing between the two, we seem to favour sex.
After all, survival is meaningless to evolution without reproduction. And who could blame us when sex has evolved to be so darn fun? Disgust and mating strategy. Evolution and Human Behavior. Feelings of disgust and disgust-induced avoidance weaken following induced sexual arousal in women.
PloS one, 7 9 , e Evolutionary psychology and the emotions. The expression of emotions in man and animal Vol. University of Chicago Press. A guide to recognizing emotions from facial clues. Biological Reviews, 78 3 , Social functionalism and the evolution of emotions.
Sexual and emotional variables influencing sexual response to erotica. Behaviour research and therapy , 35 3 , Fears, phobias, and preparedness: Toward an evolved module of fear and fear learning.
Psychological review, 3 , How the mind works. A perspective on disgust. Psychological review, 94 1 , Adaptive significance of female physical attractiveness: Role of waist-to-hip ratio. Journal of Personality and Social Psychology, 65 2 , Averageness, symmetry, and parasite resistance. Human nature Hawthorne, N. Facial sexual dimorphism, developmental stability, and susceptibility to disease in men and women. Evolution and Human Behavior, 27 2 , What and where are the primary affects?
Some evidence for a theory. Perceptual and Motor Skill, 18, Integrative and Comparative Biology, 14 1 , Sex differences and sex similarities in disgust sensitivity. Personality and Individual Differences, 51 3 , Is the relationship between pathogen avoidance and ideological conservatism explained by sexual strategies?
Microbes, mating, and morality: Journal of Personality and Social Psychology, 97 1 , Should I put in my diaphragm?: Sex- guilt and turn-offs.