Why We Love: The Nature and Chemistry of Romantic Love

by Helen Fisher

Lust, the craving for sexual gratification, emerged to motivate our ancestors to seek sexual union with almost any partner. Romantic love, the elation and obsession of “being in love,” enabled them to focus their courtship attentions on a single individual at a time, thereby conserving precious mating time and energy. And male-female attachment, the feeling of calm, peace, and security one often has for a long-term mate, evolved to motivate our ancestors to love this partner long enough to rear their young together.

In fact, in a survey of 166 varied cultures, anthropologists found evidence of romantic love in 147, almost 90 percent of them.

This phenomenon is related to the human inability to feel romantic passion for more than one person at a time.

One of the primary symptoms of romantic love is obsessive meditation about the beloved. It is known to psychologists as “intrusive thinking.” You simply can’t get your beloved out of your head.

A team of neuroscientists recently concluded that romantic love normally lasts between twelve and eighteen months.

They have good reason. In a recent poll of American men and women, 60 percent of men and 53 percent of women admitted to “mate poaching”; they had tried to woo another’s lover away to make a new committed partnership with them.40 In fact, a study of thirty cultures showed how common mate poaching is around the world.41 So like mountain bluebirds, humans are possessive.

The human tendency to stalk, even murder a straying lover probably comes from this animal tendency to guard a mate.

Elevated levels of dopamine in the brain produce extremely focussed attention,2 as well as unwavering motivation and goal-directed behaviors.

Elevated concentrations of dopamine in the brain produce exhilaration, as well as many of the other feelings that lovers report—including increased energy, hyperactivity, sleeplessness, loss of appetite, trembling, a pounding heart, accelerated breathing, and sometimes mania, anxiety, or fear.7

Dependency and craving are symptoms of addiction—and all of the major addictions are associated with elevated levels of dopamine.

When a reward is delayed, dopamine-producing cells in the brain increase their work, pumping out more of this natural stimulant to energize the brain, focus attention, and drive the pursuer to strive even harder to acquire a reward: in this case, winning one’s sweetheart.9 Dopamine, thy name is persistence.

As dopamine

increases in the brain, it often drives up levels of testosterone, the hormone of sexual desire.

increasing levels of this stimulant generally produce exhilaration, excessive energy, sleeplessness, and loss of appetite—some of the basic characteristics of romantic love.

In 1999, scientists in Italy studied sixty individuals: twenty were men and women who had fallen in love in the previous six months; twenty others suffered from unmedicated obsessive-compulsive disorder (OCD); twenty more were normal, healthy individuals who were not in love and were used as controls. Both the in-love participants and those suffering from OCD were found to have significantly lower levels of serotonin than did the controls.13

When

their responses were recorded and statistically analyzed, the results were revealing: feelings of intense romantic love were triggered almost equally by photographs, songs, and memories of the beloved.16

Humans evolved from tree-living ancestors who needed exceptional vision to survive high above the ground. Those with bad eyesight must have misjudged where fruit and blossoms hung, then missed their mark as they leapt from one branch to another and fell and broke their necks. As a result, all higher primates have large brain regions devoted to the perception and integration of visual stimuli. In fact, for decades psychologists have emphasized the important role of visual appearances in stimulating feelings of romantic attraction.

Perhaps our most important finding was activity in the caudate nucleus. This is a large C-shaped region that sits deep near the center of your brain (see diagram here).

those who scored higher on the Passionate Love Scale also showed more activity in a specific region of the caudate when they looked at the picture of their sweetheart.

Sure enough, our subjects who were in longer relationships showed activity in the anterior cingulate cortex and the insular cortex, just like the London study.

Neuroscientist Don Pfaff defines a drive as a neural state that energizes and directs behavior to acquire a particular biological need to survive or reproduce.39 We have lots of drives. They lie along a continuum. Some, like thirst and the need for warmth, cannot be extinguished until satisfied. The sex drive, hunger, and the maternal instinct, on the other hand, can often be redirected, even quelled with time and effort. I think the experience of falling in love lies somewhere along this continuum.

Very important, all of the basic drives are associated with elevated levels of central dopamine.40 So is romantic love. And like all the other drives, romantic love is a need, a craving. We need food. We need water. We need warmth. And the lover feels he/she needs the beloved.

In one study researchers scanned the brains of a group of young heterosexual men using the fMRI brain scanner. The men were shown three types of videos: some were erotic, some relaxing, some related to sports.11 Each volunteer wore a custom-built pneumatic pressure cuff around his penis to record firmness. The pattern of brain activity was quite different from the one we found among the love-sick subjects in our brain scanning project. Lust and romantic love are not the same.

Men like to look. They are sexually turned on by visual stimuli.

Women are generally more turned on by romantic words, images, and themes in films and stories. Women’s sexual fantasies also include more affection, commitment, and sex with familiar partners.23 And women like to yield. About 70 percent of American men and women fantasize while making love.

Norepinephrine, another stimulant that probably plays a role in romantic love, also stimulates the sex drive. Addicts who take amphetamines, known as “uppers” or “speed,” say their sex drive can be constant. This lustiness probably stems from the same biological equation:

amphetamines largely

boost norepinephrine (as well as dopamine). And norepinephrine can stimulate the prod...

Men with high baseline levels of testosterone marry less frequently, have more adulterous affairs, commit more spousal abuse, and divorce more often. As a man’s marriage becomes less stable, his levels of testosterone rise. With divorce, his testosterone levels rise even more. And single men tend to have higher levels of testosterone than married men.65

The reverse can also happen: as a man becomes more and more attached to his family, levels of testosterone can decline. In fact, at the birth of a child, expectant fathers experience a significant decline in levels of testosterone.66 Even when a man holds a baby, levels of testosterone decrease.

This is probably why men and women in long stable marriages tend to spend less time in their bedroom making love.

romantic love did not evolve to help us maintain a stable, enduring partnership. It evolved for different purposes: to drive ancestral men and women to prefer, choose, and pursue specific mating partners, then start the mating process and remain sexually faithful to “him” or “her” long enough to conceive a child. After the child is born, however, parents need a new set of chemicals and brain networks to rear their infant as a team—the chemistry of attachment. As a result, feelings of attachment often dampen the ecstasy of romance, replacing it with a deep sense of union with a mate.

elevated levels of dopamine—the neurotransmitter of romance.

Symmetry: The “Golden Mean”

Highly symmetrical men also get reproductive perks. They begin to have sex some four years earlier than their lopsided peers; they have more sex partners and more adulterous affairs as well.21 Women also achieve more orgasms with symmetrical men,22 even when this relationship is not emotionally satisfying to them. And when a woman has an orgasm with a well-proportioned man, her orgasmic contractions suck up more of his sperm.23

Women with a waist-to-hip ratio of around 70 percent are more likely to bear babies, Singh reports. They possess the right amount of fat in the right places—due to high levels of bodily estrogen in relation to testosterone. Women who vary substantially from these proportions find it harder to get pregnant; they conceive later in life; and they have more miscarriages. Egg-shaped, pear-shaped, or stick-shaped: differently shaped women also suffer more from chronic diseases, such as diabetes, hypertension, heart disease, certain cancers, and problems with circulation. They are also prone to various personality disorders.

In our sample, men tended to show more activity than women in brain regions associated with visual processing, particularly of the face.

This brain activity could also help explain why men generally fall in love faster than women.

When our subjects looked at their beloveds, men tended to

show more positive activity in a brain region associated with penile erection.

Psychologists report that men want to help women, to solve their problems, to be useful by doing something.42 Men feel manly when they rescue a damsel in distress.

In fact, the male brain is well built to assist women.

Men are, on average, more skilled at all sorts of mechanical and spatial tasks than women are. Men are problem solvers.

On average, women everywhere in the world are more skilled with the nuances of language, an ability linked to the female hormone, estrogen.

When women looked at the photo of their beloved, they tended to show more activity in the body of the caudate nucleus and the septum—brain regions associated with motivation and attention. Parts of the septum are also associated with the processing of emotion. Women also showed activity in some different brain regions, including one associated with retrieval and recall of memories and some associated with attention and emotion.

In fact, women everywhere in the world are more attracted to partners with education, ambition, wealth, respect, status, and position—the kinds of assets their prehistoric predecessors needed in a parenting partner. As scientists sum this up: men look for sex objects and women look for success objects.

Perhaps this feminine pragmatism explains why women fall in love more slowly than men do.

But of all the forces that guide your mate selection, I think the most important is your personal history, the myriad childhood, teenage, and adult experiences that have shaped and reshaped your likes and dislikes throughout your life. All these combine to create your largely unconscious psychological chart, what is called your “love map.”

As psychologist Geoffrey Miller argues, many of our exceptional human traits, such as our ornate language skills, our affinity for all kinds of sports, our religious fervor, our humor and moral virtue, are too ornate, too metabolically expensive, and too useless in the struggle for existence to have evolved merely so we could survive another day. They must have emerged, at least in part, to help us court and win the mating game.