Why We Love (11 page)

The prefrontal cortex must be involved. This assemblage of brain regions that lie behind the forehead is called the “central executive” because it collects data from our senses, weighs them, integrates thoughts with feelings, makes choices, and controls our basic drives (see diagram
here
). It is here that we reason, deliberate, and decide. With various regions of the prefrontal cortex we also monitor rewards. And several parts have direct connections to the caudate nucleus.
43
Someday someone will identify those regions of the prefrontal cortex that help to orchestrate romantic love.

But we are coming to some understanding of the drive to love.

And what an elegant design. This passion emanates from the motor of the mind, the caudate nucleus; and it is fueled by at least one of nature’s most powerful stimulants, dopamine. When one’s passion is returned, the brain tacks on positive emotions, such as elation and hope. When one’s love is spurned or thwarted instead, the brain links this motivation with negative feelings, such as despair and rage. And all the while, regions of the prefrontal cortex monitor the pursuit, planning tactics, calculating gains and losses, and registering one’s progress toward the goal: emotional, physical, even spiritual union with the beloved.

“The BRAIN—is wider than the sky—,” wrote Emily Dickinson.
44
Indeed, this three-pound blob can generate a need so intense that all the world has sung of it: romantic love. And to make our lives even more complex, romantic passion is intricately enmeshed with two other basic mating drives, the sex drive and the urge to build a deep attachment to a romantic partner. Ah, the web of love. How these forces feed the flame of life.

4

Web of Love:
Lust, Romance, and Attachment

O love is the crooked thing,

There is nobody wise enough

To find out all that is in it,

For he would be thinking of love

Till the stars had run away

And the shadows eaten the moon.

Ah, penny, brown penny, brown penny,

One cannot begin it too soon.

William Butler Yeats

“Brown Penny”

Love is “as sweet and musical / As bright Apollo’s lute, strung with his hair. / And when Love speaks, the voices of all the gods / Makes heaven drowsy with the harmony.”
1
Love is a harmony, as Shakespeare wrote, sometimes even a cacophony of sensations. Exuberance, tenderness, compassion, possessiveness, rapture, adoration, longing, despair: romance is a kaleidoscopic pattern of shifting needs and feelings all tethered to a celestial being on whose slightest word or smile one dangles, spinning with hope and joy and craving. Complexity, thy name is love.

Yet with time and circumstance, nature has built a few major chords within this symphony. Romantic love is deeply entwined with two other mating drives:
lust—
the craving for sexual gratification; and
attachment
—the feelings of calm, security, and union with a long-term partner.
2

Each of these basic mating drives travels along different pathways in the brain. Each produces different behaviors, hopes, and dreams. And each is associated with different neurochemicals. Lust is associated primarily with the hormone testosterone in both men and women. Romantic love is linked with the natural stimulant dopamine and perhaps norepinephrine and serotonin. And feelings of male-female attachment are produced primarily by the hormones oxytocin and vasopressin.

Moreover, each brain system evolved to direct a different aspect of reproduction. Lust evolved to motivate individuals to seek sexual union with almost
any
semi-appropriate partner. Romantic love emerged to drive men and women to focus their mating attention on a preferred individual, thereby conserving invaluable courtship time and energy. And the brain circuitry for male-female attachment developed to enable our ancestors to live with this mate at least long enough to rear a single child through infancy together.
3

All three of these brain networks—lust, romantic attraction, and attachment—are multipurpose systems. In addition to its reproductive purpose, the sex drive serves to make and keep friends, provide pleasure and adventure, tone muscles, and relax the mind. Romantic love can stimulate you to sustain a loving partnership or drive you to fall in love with a new person and initiate divorce. And feelings of attachment enable us to express genuine affection for children, family, and friends, as well as a beloved.

Nature is conservative. When she has a good design, she sticks with it, expanding its uses to suit many situations. But the primary purpose of these interlocking drives is to motivate us to seek an array of sexual partners, choose one to dote upon, then remain emotionally engaged with “him” or “her” at least long enough to rear a child together—the basics of the mating game.

To understand how romantic passion affects the sex drive and feelings of long-term attachment, I embarked on a research project with Jonathan Stieglitz, then a student at Rutgers University. We mined MedLine, PubMed, and other search engines on the Internet for academic articles illustrating how the chemistry of these three mating drives—lust, romantic attraction, and attachment—affect one another.

Indeed, romantic love weaves its way through these other brain networks in ways that both enrich and tear the fabric of our lives.

On Lust

“What arms and shoulders did I touch and see, / How apt her breasts were to be pressed by me, / How smooth a belly under her waist saw I, / How large a leg, and what a lusty thigh. / To leave the rest, all liked me passing well; / I clinged her naked body, down she fell: / Judge you the rest, being tired she bade me kiss; / Jove send me more such afternoons as this!”
4
Ovid, the Roman poet, was one of countless millions who have savored lust.

Lust is a primordial human feeling. It is unpredictable, too. The craving for sexual fulfillment can pop up in your mind as you are driving in your car, watching a movie on TV, reading in the office, or daydreaming on the beach. And this urge is very different from the feeling of romantic love. In fact, few people in Western societies confuse the elation of romance with the longing for sexual release.
5

People in far different cultures also easily distinguish between these feelings.
6
On the Polynesian island of Mangaia, “real love” is called
inangaro kino,
a state of romantic passion quite distinct from one’s sexual desires. In their native language, the Taita of Kenya call lust
ashiki
while they refer to love as
pendo.
7
And in Caruaru, a town in northeast Brazil, locals say, “
Amor
is when you feel a desire to always be with her, you breathe her, eat her, drink her, you are always thinking of her, you don’t manage to live without her.”
8
Paixao,
on the other hand, is “horniness” and
tesao
is “a very strong sexual attraction for a person.”
9

These people are correct to regard these feelings as distinct. Scientists have recently established that lust and romantic love are associated with different constellations of brain regions.
10
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.

And just as people everywhere have concocted love potions to spur romance, they have tried all sorts of potions to trigger lust—what an Italian proverb calls “the oldest lion of them all.”

The Hormone of Desire

“Candy is dandy, but liquor is quicker,” quipped Ogden Nash. Everywhere humankind has used what they hoped was an aphrodisiac to trigger lust. When the tomato first crossed the Atlantic from the Americas, the Europeans thought this juicy red fruit would spark the sexual appetite; they called it the “love apple.” Shark’s fins, bird’s nest soup, powdered rhinoceros horn, curry, chutney, mandrake root, chocolate, hyena eyes, caviar, clams, oysters, lobsters, dove brains, goose tongues, apples, bananas, cherries, dates, figs, peaches, pomegranates, asparagus, garlic, beer, perspiration: scents and tastes and ointments of dazzling variety have been employed to charm reluctant partners into bed.

The Elizabethans served free prunes in brothels because they were convinced this spurred lust. In past centuries Arabs tried to lure hesitant women into sampling a bit of camel hump to pique their sexual desire. Pliny wrote that hippopotamus snouts would do the trick. The Aztecs saw sexual magic in goat and rabbit parts because these animals were fast breeders. Sea slugs caught the fancy of the Chinese, largely because these strange animals enlarge when touched. And Europeans historically pulverized a certain type of beetle found in southern Europe to incite sexual desire; they called it Spanish fly.
12

Eating increases blood pressure and the pulse rate, raises body temperature, and sometimes makes us sweat, physiological changes that also occur with sex. Perhaps this is why men and women have long associated different foods with sexual excitement. But nature has made only one true substance to stimulate sexual desire in men and women—testosterone, and to a lesser degree, its kin, the other male sex hormones.

This is well established. Men and women who have higher circulating levels of testosterone tend to engage in more sexual activity.
13
Male athletes who inject testosterone to elevate their strength and stamina have more sexual thoughts, more morning erections, more sexual encounters, and more orgasms. And women who take testosterone in middle age boost their sexual desire. The male libido peaks in the early twenties, when levels of testosterone are highest. And many women feel more sexual desire around ovulation, when levels of testosterone increase.
14

As elevated levels of testosterone stimulate the sex drive, declining levels dampen it. Both sexes have fewer sexual fantasies, masturbate less regularly, and engage in less intercourse as they age.
15
Poor health, unhappiness, overwork, lack of opportunity, laziness, and boredom undoubtedly contribute to this waning lust. But with age, levels of testosterone decline, often depressing sex desire.

Some two-thirds of middle-aged women do not experience any decline in libido, however.
16
This, too, may be due to testosterone. As the estrogens decline with menopause, levels of testosterone and the other androgens become unmasked: these potent hormones can finally express themselves more fully. Indeed, they do. In one study of middle-aged women, almost 40 percent complained that they were not having enough sex.
17

When it comes to sexual desire, people vary, in part because levels of testosterone are inherited.
18
Levels also fluctuate according to the day, the week, the year, and the life cycle. Moreover, the balance of testosterone, estrogen, and other bodily ingredients, as well as social circumstances and a host of other factors, all play a role in when, where, and how often we feel lust.
19
Nevertheless, testosterone is central to this appetite. And this primordial chemical can swamp the thinking brain. As poet Tony Hoagland said of lust, “As long as there is desire, we are not safe.”
20

Men and women are often sexually stimulated by different things, however. Men like to look. They are sexually turned on by visual stimuli. Even when men fantasize, they conjure up vivid images of body parts and copulation.
21
This lascivious peering probably boosts levels of testosterone. When male monkeys see a sexually available female or watch a companion copulate with a female, their levels of testosterone soar.
22
So the men who go to strip bars or look at “girlie” magazines are probably boosting levels of testosterone and triggering lust.

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.
24
But as conquest is at the core of most men’s mental plots, active surrender is prevalent in women’s sexual reveries.
25

These tastes for conquest and surrender have nothing to do with rape. Less than half of 1 percent of men enjoy forcing a woman into coitus; and less than half of 1 percent of women want to be coerced into copulation.
26
Still, American women are twice as likely as men to actively fantasize about being “done to” as opposed to “doing.”
27

Danger, novelty, particular smells and sounds, love letters, candy, endearing conversations, sexy clothes, swaying music, elegant dinners: many cues can trigger that “eternal thirst,” as poet Pablo Neruda called the sex drive. How do feelings of romantic love affect this primordial brain circuit, lust?

Romance Triggers Lust

Surely you have noticed that when you fall in love, your ardor stimulates the sex drive. Novelists, dramatists, poets, and songwriters all rhapsodize about this urge to kiss, cuddle, and make love to someone you adore.

Why do we feel lust when we fall in love?

Because dopamine, the liquor of romance, can stimulate the release of testosterone, the hormone of sexual desire.
28