What Scientists Know About Sex on the Male Brain

Studying brain activation and sex in male animals has revealed some principles that probably sound familiar to those of primarily concerned with sex in humans.

• When male fruit flies are surrounded by high-intensity light that enables them to see whether the other fruit flies around them are male or female, they are more interested in having sex with females than they are in fighting males.
• When male fruit flies are surrounded by low-intensity light that doesn't allow them to see whether the other fruit flies around them are male or female, they are more inclined to aggression with males than to having sex with females.
• The same parts of the brain that make the sight of a female fruit fly sexy to a male fruit fly (we are not given any data on homosexual fruit flies) also record the "scent of a woman." They respond to pheromones.
• When low-intensity light is delivered inside the brain of a male mouse, its ventromedial hypothalamus is stimulated just enough that it becomes interested in sex. In this case, the light doesn't have anything to do with how well the mouse can see, because it comes through a fiber optic cable placed into the mouse's brain.
• When more light produces more stimulation in the same part of the male mouse's brain, aggressive impulses take over.

Scientists can't (or at least scientists don't) genetically engineer humans to observe how stimulating different parts of their brains affects their sexual behavior. However, studies of the brains of male animals imply some principles for sexual behavior in male humans:

• Men get into fights in dark, smelly places. Dark places are not a natural turn on for most men (all other things being equal).
• Men are more inclined to sexual attraction when they can see their potential partners.
• Male humans, like male fruit flies and male lab mice, respond to the odor of pheromones from potential mating partners. High concentrations of pheromones, however, start trigger more than just sexual behavior but also aggressive behavior.
• Men can get so turned on that they have to exercise rational control over aggressive behaviors. Anything that interferes with rational control, such as alcohol consumption or a personality disorder (which in turn may be linked to a defect in the production of certain proteins in the brain), increases the risk of violence.

In human males, there is one more important part of the equation. Testosterone levels determine how active and coordinated the brain will be in the pursuit of sex. A man with low testosterone level will still be sexually stimulated in the presence of a potential sex partner, but fewer neurons in his brain will fire if he is rejected. For instance a man on meeting a potentially available female might say, "Can I have your number," the woman reply, "No," and the man reply "OK." A man with higher testosterone levels makes more neuron to neuron connections in his brain that involve the sex center might also be rejected but ask again. And again. A man whose brain makes too much of another chemical, tachykinin, might make even more connections between sex and aggression and get out of control.

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What does science tell us about women who enjoy situations like those portrayed in Fifty Shades of Grey? One study found that women who had read the book were more likely to be involved with a verbally abusive partner and more likely to suffer eating disorders. Another study found that women who had read all three books in the trilogy were more likely to have had multiple sex partners and to be involved in binge drinking. So what's the healthy response to these facts?

Sex that is based on impulse, aggression, and domination on one side and acceptance and submission on the other, especially between (or among) strangers, is usually destructive. Romance isn't dead. Your thinking brain needs to be engaged as much as your sexually impulsive brain to create healthy sex. Because of the way our brains are wired to be aggressive, becoming addicted to rough sex is easy, and breaking that addiction is hard. For the best sex and the healthiest sex, keep romance in your life, whether you are a man or a woman.