Fifty Shades of Gray Matter: Sex, Violence, and the Brain

In 2011, the British novelist E. L. James released an astonishingly popular romantic novel entitled Fifty Shades of Grey. Selling over 125,000,000 copies worldwide in just four years, the novel chronicles the relationship between business tycoon Christian Grey and new college graduate Anastasia Steele, with explicit and, for some, intoxicating descriptions of bondage, discipline, dominance, submission, sadism, and masochism, sex with explicit violence.

Why would a novel on these themes become so popular with so many people so fast? Explaining literary success is beyond the scope of this site, but there are answers in science to the questions about the links of sex, violence, and the way our brains work.

Aggression Is a Fundamental Human Behavior

What is aggression? At its simplest level, aggression is attacking other humans, animals, inanimate objects, or oneself. In humans, aggression can be physical, verbal, or more subtle, sometimes a matter of what we don't do as well as what we do. Aggression can take the form of violence. In times of scarcity, aggression is directed toward defending territory, maintaining status, or obtaining food, shelter, or sex.

Aggression Is Activated Independently of Rational Thought

In human beings, aggression is so essential to maintaining life that it can be activated independently of rational thought. Aggressive emotions are "brain states," according to some researchers such as neurobiologist David Anderson from the California Institute of Technology, that are activated independently of memory or critical thinking. 

Since it's easier to study the brains of animals than it is to study the brains of humans, Anderson and his colleagues studied aggression and brain changes in animals. Almost all animals and humans respond to fear with either freezing in place or flight. The result of anger is usually to fight. The Cal Tech researchers bred genetically modified fruit flies that had specific brain cells that could be activated by light. They wanted to determine which cells in fruit fly brains can be stimulated to cause freezing, flying away, or aggression against other fruit flies.

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Programmed Aggression in Fruit Fly, Rodent, and Human Males

The scientists found that in male fruit flies, activating certain brain cells could result in aggressive behavior toward potential mates. Blocking the activity of those brain cells stopped the aggressive behavior, although the male flies were still interested in sex. Anderson and coworkers concluded that the male-specific brain cells produce a specific protein that triggers aggressive behavior in fruit flies.

The scientists then identified a group of about 2,000 neurons in part of the brain known as the ventromedial hypothalamus in male laboratory mice that were closely associated with aggressive behavior. About 20 percent of these neurons were also associated with sexual behavior. As with the fruit flies, the researchers created genetically engineered mice with neurons that can be activated by exposure to light. They found that using a tiny fiber optic cable to deliver low-intensity light into this area of the mouse's brain could stimulate mounting and other sexual behavior, but high-intensity light triggered aggressive, fighting behavior.

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.