Academics at the Department of Psychology of Northern Illinois University point out in a recent study that to have sex, we have to overcome strong feelings of disgust.
Their study, published in the journal Archives of Sexual Behaviour, was partly inspired by the observation that basically the human body is pretty disgusting.
It secretes fluids, harbours germs, and, generally, we find contact with anything that has been in a stranger's body orifice extremely unpleasant.
The genitals and mouth are involved in sex, yet are also the regions that might be associated with most disgust.
However, despite all that possible repulsion of such orifices and secretions, we still make love.
The authors of the study entitled "Effects of Subjective Sexual Arousal on Sexual, Pathogen, and Moral Disgust Sensitivity in Women and Men" point out that the act of physical intimacy presents us with an evolutionary dilemma: We want to avoid contamination from potentially dangerous substances, and yet we are also motivated to attain mates, as we do need to pass on our genes.
Ellen Lee, James Ambler and Brad Sagarin, the authors of the study, suggest a possible way nature has resolved this dilemma: an internal mechanism that evolved in our brains inhibiting disgust in "reproductively-relevant situations."
Basically this means that sexual arousal reduces revulsion.
The study found that in women, sexual arousal significantly lowered sexual disgust. The authors argue that their findings support the evolutionary theory that erotic arousal inhibits distaste, which facilitates a willingness to engage in high-risk, but evolutionarily necessary, procreation.
The authors also argue that this effect could be particularly important for women.
In this research men showed very low levels of sexual disgust, even when not sexually aroused, indicating a potential "floor effect" — in other words, the measured repugnance was so small in the first place that it had nowhere to go in terms of getting lower with sexual arousal.
Previous research has found women more sensitive than men to revulsion, particularly to sexual disgust.
However the authors also point out that the item on the sexual disgust subscale that showed the least decrease in revulsion with arousal was sexual attention from a disliked source: (''Finding out that someone you don't like has sexual fantasies about you'').
Being turned on does not appear to make unwanted sexual attention or partners more palatable, particularly in women.
Now a brand new study entitled "Disgust and mating strategy" has found that our feelings and attitudes to disgust could also be part of our personality or orientation, and in particular is linked to mating, love or sex strategies.
The study from The University of Texas at Austin, and Bilkent University, Turkey, started from the fact that people generally vary in the attitudes and desire for longer-term, committed relationships versus short-term, uncommitted connections.
It follows we should also expect those who are more inclined toward "short term mating" to experience lower levels of sexual disgust.
The authors, Laith Al-Shawaf, David Lewis and David Buss point out successful short-term mating strategies typically involve multiple sex partners, desire for sexual variety, and brief intervals of time before sexual intercourse.
This strategy should be difficult to implement in the presence of high levels of sexual disgust: Those with higher levels of such repulsion are less likely to be comfortable with casual sex, multiple partners, and sex that occurs before sufficient information can be acquired about the health and hygiene status of potential mates.
The authors, therefore, propose that a crucial component of a successful short-term mating strategy is lower sexual disgust. In contrast, less repulsion over certain aspects of sex are not necessary for the successful pursuit of a more monogamous strategy.
One possible speculation from these new findings is that higher levels of sexual disgust may even facilitate the implementation of committed mating strategies by inhibiting short-term mating and deterring those in committed relationships from sexual infidelity.
The research asked participants to rate how disgusting they find a variety of potentially repellent situations, for example, "a stranger of the opposite sex intentionally rubbing your thigh in an elevator" and "performing oral sex."
The study, published in the academic journal "Evolution and Human Behavior," found that a stronger disposition toward short-term mating is associated with reduced sexual disgust.
But the investigation also found that the relationship between physical attractiveness and short-term mating was significantly stronger in men. More physically attractive men are keener on short-term flings, while more physically attractive women are not in fact more interested in such an approach to their sex lives, compared to less attractive women.
The authors argue that physically attractive women may have a larger number of sexual partners simply because they have more eager suitors, or have sex at an earlier age, but not necessarily because they are pursuing a "short term mating strategy."
Women's attractiveness in this research was not associated with desire for or positive attitudes toward short-term mating.
The authors argue that shorter-term mating looms larger in men's than in women's relationship psychology, and is pursued more vigorously by men because as a strategy it has evolutionary benefits for men, in terms of passing on more genes.
This pattern is apparently mirrored in other species: more attractive male birds devote less effort to parenting when they can translate their physical attractiveness into "extra-pair copulations."
Maybe the quality of your sex life generally can be predicted by levels of disgust.
Might this new research possibly also suggest an intriguing new way of predicting how likely your partner is to stay or stray?
This might be predicted by how disgusted they become by aspects of intimacy, or perhaps, how rapidly do their levels of disgust vanish as they get turned on?
Raj Persaud and Peter Bruggen are joint podcast editors for the Royal College of Psychiatrists and also now have a free app on iTunes and Google Play store entitled "Raj Persaud in conversation," which includes a lot of free information on the latest research findings in mental health, psychology, psychiatry, and neuroscience, plus interviews with top experts from around the world.