Casual sex doesn’t exist , says biological anthropologist Helen Fisher:
Question: Can casual sex trigger love?
Helen Fisher: I think that all three of these brain systems can interact with one another, particularly when you have sex with somebody. Any kind of sexual stimulation of the genitals triggers the dopamine system in the brain and can push you over that threshold into falling in love with that person. And in fact, with orgasm, theres a real flood of oxytocin and vasopressin, other chemicals in the brain associated with the feeling of deep attachment. So, casual sex is really never casual unless youre so drunk you cant remember it; something happens. As a matter of fact, in one study of over a thousand people, over 50% of both men and women reported that their first kiss of somebody was sort of the kiss of death. They had begun quite attracted to a person sexually and romantically and then when they kissed them, it was so horrible for them that it turned them off completely. So, casual sex is just plain old not casual. Something can happen. You can either fall madly in love with this person, or you can begin a deep sense of attachment to them.
As a matter of fact, Ive been working with a graduate student named Justin Garcia, and he and I believe that people go into hookups, or one-night stands hoping to trigger a longer relationship. And in fact, in a study that he did of 515 men and women in a college in the northeast, he asked them why they went into this hookup; this one-night stand. Fifty percent of women and 52% of men reported that they went into the sexual experience hoping to trigger a longer relationship, and in fact, 1/3 of them did.
So, consciously, when people go into the one-night stands, they probably arent thinking, oh, Im going to trigger the brain system, or the dopamine system in the brain and make this person fall in love with me, but somehow, intuitively, they know that sex is powerful and that it can trigger powerful feelings of love.
(Via: Postmodern Conservative )