Science of Love, Sex, and Babies

The “psych” in semen

Posted in news by jenapincott on March 25, 2009

hypnotize2My post on mind control properties in semen still attracts a disturbing amount of attention. So to appease your curiosity — and, I’ll admit it, mine — I’ve decided to do a little more investigation into the compounds in semen that may enter the bloodstream after sex. Some may have an indirect effect on the recipient’s hormones. A few may breach the blood-brain barrier, directly influencing mood and sex drive. Several, but not all, of the chemicals have been studied and proven to pass through the vaginal walls. From an evolutionary perspective, mood-modulating components in semen may give a woman an incentive to be in a committed relationship with regular, frequent sex. Apparently, the goo is bonding.

The information below comes from SUNY Albany evolutionary psychologists Gordon Gallup and Rebecca Burch, whose fascinating study on semen and depression I describe in BLONDES. Gallup and Burch wrote a chapter, “The psychobiology of human semen,” published in a compilation of research on sexuality. What they describe, I think, is fascinating.

The primary putative mind-altering ingredients in semen:

Luteinizing hormone: astounding concentration in semen; linked to high sperm count and motility. Absorption into female bloodstream may facilitate or even induce ovulation.

Prolactin: influences maternal behavior, oxytocin secretion; mediates bonding

Estrone and estradiol: assists in recipient’s absorption of other compounds such as progesterone; may boost woman’s sexual motivation and mood

Testosterone: may increase sex drive and motivation; the more intercourse, the higher the testosterone levels in women, and the stronger the sexual desire. More than half the amount of testosterone in sperm has been found to be absorbed by the vagina.

Cytokines: these are the “warriors,” they suppress immune reaction to semen invading the vagina and cervix and therefore increase likelihood of pregnancy

Enkephalins: these opioids may contribute to orgasmic experience. They may decrease anxiety and cause drowsiness after sex.¬† There’s also speculation that they assist in immune function and “reinforcing effects” — making a woman come back for more, i.e. addiction¬† (although the absorption rate in female bloodstream is unknown)

Oxytocin: assists in stimulation of ovulation, increases production of other hormones, initiates bonding, facilitates orgasmic contractions; may strengthen bonding and make sexual activity more rewarding

Placental proteins, including human chorionic gonadotrophin (hcg) and human placental lactogen: associated with sperm motility; may increase chances of pregnancy

Relaxin: made in the prostate, this hormone may facilitate fertilization, implantation, and uterine growth. The role of relaxin suggests that women should keep having a lot of sex during pregnancy because sperm has pregnancy-maintaining properties. Relaxin also facilitates implantation and prevents preterm labor.

Thyrotropin-releasing hormones: potential anti-depressive; works by stimulating the release of thyroid-stimulating hormone, which in turn triggers hormone production in the mood-mediating thyroid gland. In pill form, it’s used to treat PMS and depression.

Serotonin: increases sperm motility.¬† It also mediates mood, although not much known yet about vaginal absorption. Even if it doesn’t make it to the brain, it may indirectly alter behavior and emotions by contributing the building blocks of serotonin

Melatonin: increases effects of steroid hormones; induces sleepiness and fatigue, which may help the woman relax after sex; may stimulate reproductive function, also mood mediator; low melatonin levels are associated with depression and “reality disturbance”

Tyrosine: a precursor of neurotransmitters such as dopamine, the hormone of reward and addiction, and norepinephrine, involved in attention and arousal

Oh, and there’s also sperm in there, the DNA-bearing courier. Sperm is less than 3 percent the total volume of semen. But as it turns out, the bath water is nearly as important as the baby.

n.b. Although not yet studied, researchers suspect that these chemicals in semen may also enter the bloodstream through mucous membranes when having oral and anal sex. If so, straight women aren’t the only lucky recipients.

Women’s scent has mind control properties

Posted in news by jenapincott on January 10, 2009

bxp68578I was shocked by the overwhelming response (nearly 60,000 views!) to my post, “Semen has mind control properties.” Many readers said they think it’s a fascinating idea — that there are proteins and/or hormones in semen that subtly affect a woman’s sexual behavior. But what “secret weapons” do women have to “control” men?

I have a few responses, which are detailed in my book.

1. Women are (generally) the choosier sex. From an evolutionary standpoint, we’re pickier about our sexual partners because we have more at stake in the event of a pregnancy. Everywhere around the world, even in the most egalitarian countries, women desire fewer lovers than men do. Although women make trade-offs depending on their circumstances, we’re more about quality (even for flings). This by default gives women a sort of upper hand.

Now the sexier stuff:

2. Chemicals released during sex affect men, too. When he orgasms, his body releases vasopressin, a neurohormone associated with bonding (and drowsiness — it’s one reason why men fall into contented postcoital slumbers). This means that sexual intimacy may make a guy more attached to his lover. How likely is this? Intriguingly, a lot may have to do with his particular vasopressin receptor genes.

3. A woman’s scent may have mind control properties. Guys tend to prefer a woman’s body odor around the time she’s most likely to conceive (as described in BLONDES). On a subconscious level, men have been found to behave differently around this time of a woman’s cycle. According to studies such as this one at UCLA, women report that their partners are more jealous, loving, possessive, and attentive when women have high levels of luteinzing hormone in their system, a sign of imminent ovulation. In the famous stripper study, johns were also much more generous — paying up to twice as much — when the strippers were fertile. Scientists speculate that men are unwittingly responding to estrogen-related properties in women’s sweat and other bodily fluids. Men, meanwhile, are oblivious to why they’re acting so servile.

Bottom line is that there are no doubt many hormonal signals that give either men or women the reproductive upper hand. We’re all either sperm-zombied or pussy-whipped — that’s what some readers have quipped. But a sweeter way of looking at it is that these neurohormones also help give rise to love and long-term attachment. Not to say that chemistry could or should ever define love, but it does help explain some bonds.

Semen has mind control properties

Posted in news by jenapincott on January 8, 2009

hypnotism-0250-pg1The more a woman has sex with her partner, the more committed she becomes, and the less attracted she is to other men — at least in the short-term. I blogged about this study several weeks ago and offered explanations both hormonal and psychological. But another theory came to my attention today in the form of a study on fruit flies.

For decades, scientists have known that female Drosophila refuse sex for a period of time after contact with seminal fluid. This may give a reproductive edge to the first male with whom a female has sex. A study led by Geoffrey Findlay at the University of Washington has finally shed some light on the phenomenon. It turns out there are proteins in seminal fluid, many of which transfer to the female after sex. Some of these proteins are warrior-like — they fight the sperm of rival males. Other proteins are like hypnotists — entering the female’s circulatory system, they may hormonally dampen her interest in sex with other males. Somewhat disturbingly, the more semen a female is exposed to, the more influence the male has over her reproductive tract and her mating behavior. Semen, it seems, has mind control properties.

So what does this mean for humans? The same study hasn’t been done on men and women, but researchers speculate that many of the same proteins are in the semen of human males. “Does semen make you happier?” is one of the questions posed in BLONDES. In answering it I describe a fascinating study at SUNY Albany that found that, yes, women who are regularly exposed to their partner’s semen are less depressed than women who use condoms most of the time. Hormones and proteins are absorbed through the vagina, enter the bloodstream, and possibly breach the blood-brain barrier. Might these factors in men’s semen manipulate women’s minds (and bodies) in the way that fruit fly spunk affects female fruit flies? Perhaps, but it’s hard to prove. Women’s love lives (and psyches) are a little more complicated than those of Drosophila. After all, a woman in love with the man with whom she has unprotected sex would be happier and more faithful anyway. It’s a puzzle for all scientists who study human sexuality: Where to draw the line between chemical love and Eros? The seminal and the sacred?

n.b. Here is a list of the potential mind-altering “ingredients” in sperm.

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