Last year a sexologist did research on women engaging in various kinds of sexual activity for 30 days - and tested them to see how attractive and friendly they found (unknown) men's pictures. He was trying to prove that women engaging in PVI (penile-vaginal intercourse) would find pictures of strange men less attractive than the other women did, because they would be more bonded with their mates.

See Sexual Preference in Rams: Investigating the Role of Prolactin.

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by Mark Griffiths

Case Study - Why Do we Work

Description of the work of Princeton professor, Bartley Hoebel

[Elsewhere Hoebel has said, "Highly palatable foods and highly potent sexual stimuli are the only stimuli capable of activating the dopamine system with anywhere near the potency of addictive drugs."]

Male pheromone–stimulated neurogenesis in the adult female brain: possible role in mating behavior

[This could help explain why women choose "Don Juans" who are otherwise dismal as mates.]

The regulation of female reproductive behaviors may involve memories of male pheromone signatures, formed in part by neural circuitry involving the olfactory bulb and hippocampus.

There is ancient lore to the effect that learning to make love without orgasm is protective of health. Here's some research showing that too much fertilization-driven sex can suppress the immune system.

Males of the species Antechinus stuartii are "overtly preoccupied with copulation and die abruptly at the conclusion of the mating season."

By Jeremy P.W. Heaton, MD

Prolactin's close relationship to other hormones and neurotransmitters vital to sex, life, and aging merits review. Although prolactin hypersecretion occurs infrequently, its recognition provides an opportunity to treat a fundamental cause of sexual problems.

What is interesting about prolactin (PRL)? Most urologists know it only as a bit player in the androgen and erectile dysfunction (ED) arena. It is considered problematic (should the PRL levels be routinely measured in men with ED?) and is usually associated with alterations in desire or libido (although this is more legend than fact). We are inclined to forget that PRL plays similar but mirror image roles in female reproductive medicine, with the addition of eponymous roles in lactation.

One day while in a retreat center snack bar I heard a woman say, "Brendan, you give such great hugs that we should just put you by the chocolate section. That way, whenever we get chocolate cravings we can just get a hug from you instead!" She may have been on to something scientifically valid.

Study suggests infidelity could be part of evolutionary call for desirable mates

Women who feel an urge for sex outside of their marriages might be hearing an evolutionary call to improve the species.

New research suggests that during ovulation, when women are ready to conceive, nature may encourage them to look beyond their male partners for a better gene pool, but only if they don't find their mates sexually attractive.

Although scientists aren’t yet testing the benefits of intercourse without orgasm, here’s a report on a study demonstrating that the benefits of sex come from intercourse, not orgasm…and that oxytocin may explain those gains. (See also article on anti-stress benefits of merely holding hands and hugging) Now scientists just need to connect the dots with the "Coolidge Effect," due to which intercourse with sexual satiation gradually leads to emotional distance.