Why We Love (17 page)

In a highly original book,
The Mating Mind,
psychologist Geoffrey Miller adds to Darwin’s theory of sexual selection. He proposes that human beings have also evolved extravagant traits to impress potential mating partners.

As Miller reasons, our human intelligence, linguistic talent, and musical ability, our drive to create visual arts, stories, myths, comedies, and dramas, our taste for all kinds of sports, our curiosity, our ability to solve complex math problems, our moral virtue, our religious fervor, our impulse for charitable giving, our political convictions, sense of humor, need to gossip, creativity, even our courage, pugnacity, perseverance, and kindness are all far too ornate and metabolically expensive to have evolved solely to survive another day.
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Had our forebears needed these advanced aptitudes simply to live, chimpanzees would have developed these abilities as well. They didn’t.

Miller believes, therefore, that all these marvelous human capacities evolved to win the mating game. We are “courtship machines,” Miller writes.
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Those ancestors who could speak poetically, draw deftly, dance nimbly, or deliver fiery moral speeches were regarded as more attractive. These talented men and women produced more babies. And gradually these human capacities became inscribed in our genetic code. Moreover, to distinguish themselves, our forebears specialized—creating the tremendous variety in human personalities seen today.

Miller acknowledges that in their simple forms, many of these traits were also useful in order to survive on the grasslands of ancient Africa; these talents had
many
purposes. But these aptitudes, he believes, became more and more complex because the opposite sex
liked
them and chose to mate with verbal, musical, or otherwise talented men and women. He concludes: “The mind evolved by moonlight.”
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I agree with Miller’s thesis. Take language, for example. Our forebears only needed a few thousand words and simple grammatical constructions to say, “Here comes the lion” and “Pass the nuts.” But our flowery poetic verse, our musical brilliance, and many of our other complex human talents probably evolved, at least in part, as men and women endlessly displayed their mating qualities.

But how did ancestral men and women come to prefer these extraordinary traits in their suitors? Some brain mechanism must have simultaneously evolved in the
display choosers
to become attracted to the fancy rhymes, lyric tunes, and other flashy traits that
display producers
paraded for them.

Darwin offered little comment on how creatures actually respond to these courtship displays and prefer one mate over another. He believed this selection process was somehow linked to an appreciation of beauty. Females of all species, he wrote, were attracted to males who displayed signs of comeliness. But Darwin could not explain how this female attraction operated in the animal brain, puzzling, “It is, however, difficult to obtain direct evidence of their capacity to appreciate beauty.”
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Miller also notes this dilemma. Along with the evolution of traits in the human
display producer,
there must be some corresponding brain mechanisms in the
display chooser
to enable them to discriminate among these courtship signals, prefer some, and select a specific mating partner.

So he suggests that along with the evolution of our superb human mental and physical abilities came the “mental machinery” or “sexual choice equipment” to discriminate among and appreciate these wooing ploys. Hence, our forebears developed a taste for linguistic flair, for artistic drawings in the sand, for charismatic oratory, moral strength, and many other budding human talents—as well as the aptitudes to discriminate, remember, and judge these courtship cues.

But Miller offers no concrete suggestion as to what actually enables the display chooser to choose one wooing tactic rather than another, saying only that it is something like “a big pleasure meter” in the brain and that endorphins (the brain’s natural painkillers) might be involved.

I propose that this pleasure meter is the brain circuitry for romantic love—orchestrated largely by dopamine networks through the caudate nucleus and other reward pathways in the brain. As ancestral men and women sifted through their array of mating opportunities, the primordial brain circuitry for animal attraction evolved into human romantic love—to help the chooser choose a specific mating partner, pursue this beloved avidly, and devote his/her courtship time and energy to this reproductive prize.

When and where and why did our forebears begin to need complex language abilities and myriad other astounding talents to win a mate? Chimpanzees don’t need poetry or guitar music to bed a lover. What triggered the evolution of these myriad special human talents and the brain circuitry to be wildly drawn to one rather than another: romantic love?

It all began, as Dryden put it, “when wild in wood the noble savage ran.”

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Why We Love:
The Evolution of Romantic Love

The fountains mingle with the river,

And the rivers with the ocean;

The winds of heaven mix forever,

With a sweet emotion;

Nothing in the world is single;

All things by a law divine

In one another’s being mingle:—

Why not I with thine?

Percy Bysshe Shelley

“Love’s Philosophy”

“I seem to have loved you in numberless forms / numberless times, / In life after life, in age after age forever … / Today it is heaped at your feet, it has found its end / in you, / The love of all man’s days both past and forever.” Indian poet Rabindranath Tagore sensed that his passion for a woman had come across the eons from a mind built long ago. Indeed, we carry embedded in our brains the whole history of our species, all the circuits that our forebears built as they sang and danced and shared their wisdom and their food to impress their lovers and their friends, then passionately fell in love with “him” or “her.”

How did we come to court and love the way we do? Bad Bull didn’t shower Tia with poetry to prove he was king of elephants. Skipper found his little beaver mate one spring evening; he didn’t sing rock ’n’ roll songs to a thousand assembled female beavers to impress them first. Misha fell in love with Maria the moment Maria wagged her doggy tail and invited him to play. All animals have mating preferences. And most have evolved courtship plumage of one kind or another to dazzle their would-be lovers. But no creatures except human beings parade about with such extravagant displays as sonnets and skydiving.

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.

Moreover, I have proposed that along with all the magnificent courtship ornaments that we flaunt to persuade prospective mates, men and women have also evolved a specific brain network to respond to these traits: the circuitry for romantic love. This passion, a developed form of animal attraction, emerged to drive each of us to choose from among these myriad courtship displays, prefer a specific individual, and begin the primordial mating dance exclusively with “him” or “her.”

But Miller never tells us when, where, or why human beings evolved these special talents. And I have not explained how our species transformed from creatures who felt a temporary attraction for a “special” individual into men and women who are willing to die for “him” or “her.” Something happened deep in time to produce the human drive to love.

Love in the Trees

Palm trees, fig trees, wild pear trees, mahogany trees, evergreen trees, trees, trees, and more trees carpeted East Africa 8 million years ago. Here lived the last of our forest-dwelling ancestors. Anthropologists have little direct evidence of their daily lives. But our first forebears probably lived much as modern chimpanzees do. We share over 98 percent of our DNA with these creatures. “Common” chimps and their smaller chimp relatives called bonobos still live in what is left of that primal African environment. And chimps display many traits that our common ancestor most likely shared.

Like today’s common chimps and bonobos, our first forebears must have lived in communities, often consisting of eighty to a hundred males and females. They slept high in the forest canopy, arose after dawn, and descended to the jungle floor to wander well-worn trails in their mutual home range. Members must have met and mixed singly or in small parties, eating and socializing intensely. These human ancestors knew who was family, friend, and foe. And they chattered among themselves with at least fifty different kinds of hoots and barks, as well as with about thirty varied gestures.

Like today’s chimps, they probably used stone hammers to crack nuts, toothpicks made of twigs, and napkins from wadded grass. Like chimps they probably hurled rocks and sticks to spar for dominance, hunted monkeys, shared the meat, and made war on chimp neighbors to usurp their lands. Some were pranksters, some leaders; others brave, deceptive, curious, or belligerent. And many made friends and enemies, gave twigs as gifts, defended comrades in spats, and lingered near dying relatives.

They also made love. Today’s chimps and bonobos are among the most sexually active animals on earth. They kiss—sometimes with the deep “French kiss,” walk arm in arm, hug, stroke, pat, groom, bow to one another, and often copulate throughout most (if not all) of the female’s monthly estrus cycle. But unlike human beings, our last tree-dwelling forebears were almost certainly promiscuous—just as chimpanzees and bonobos are today.

At the height of estrus, an ancestral female may have joined a single male and left the community to copulate with him in private. But this bond was temporary; most likely they never paired for more than a few days or weeks.

Nor did they fall in love. Undoubtedly our first relatives had “favorites,” like all other creatures. But these distant kin showed none of the obsessive focus on a single mate that is so characteristic of human romantic passion. And they probably never formed a partnership to rear their young. A mother didn’t need a mate to help protect or provide for her and her child. So like chimps, mothers raised their infants by themselves.

Nevertheless, some of our forest-dwelling ancestors must have felt
more
attraction for a mating partner than others did, an affinity that would eventually develop into human romantic love. When, where, and why humanity started to love with new vigor, no one knows. But I think this journey began soon after our forebears began to descend from the trees of East Africa to build a new world on the perilous ground.

The Human Stride

The earliest hominid fossils come from northern Chad. In 2002, anthropologists reported finding an almost complete skull as well as several jaws and teeth in this Central African country.
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Some ancient kin lived here, near a shallow, freshwater lake, between 6 and 7 million years ago. They may have spent most of their days in the trees that crowded along the shore. Some must have also ventured into the open plains, sticking close to ribbons of forest that wove through the prairie grass. Perhaps they followed vultures to the half-consumed carcass of an eland or wildebeest. Maybe the bravest hurled sticks and stones at feeding lions, then stole their dinner. Some must have waded into the swampy deep as well, steering clear of dunking hippos to seize a turtle or corner a gazelle that came to drink.

We know little about these relatives. Their bones don’t even tell us whether they walked on two feet or four. But “Toumai,” as the local people call the Chad skull, was part of our human lineage. True, his brain was no bigger than a chimp’s. But he had a flatter face, a more human jaw, and more human teeth. And he and his relatives clearly courted, copulated, and bred.

Their children bred; their children’s children’s children also bred. Because by 3.5 million years ago many more hominids were roaming the gladed forests and the more open woodlands and savannahs that stretched across East Africa. Anthropologists have found hundreds of their fossilized bones and teeth. These folks had changed. Their feet, legs, hips, and skulls bespeak men and women who walked erect, on two feet instead of four.

I sing the human stride. As we balance our neck and spine above our hips, extend the leg, lock the knee, hit the ground with the heel, then roll onto the ball of the foot and spring off with the big toe, we almost effortlessly fall forward.

This single innovation would change much of life on earth. With walking, our ancestors could carry stones to throw at leopards or lions that stalked them in the dark. With walking, they could carry sticks to dig for roots and tubers. With walking, they could hurl rocks at small animals that nestled in the grass. Bipedalism also liberated their hands for gesturing and freed their mouths for words. With walking, collecting, and carrying, our forebears began their uncharted march toward modernity.

All this is fact. Now for theory. I think the human stride caused a problem for females: they became obliged to carry their babies in their arms instead of on their backs. In the trees, their quadrupedal chimplike ancestors had carried their infants on their backs. In that leafy universe a mother’s hands were free to gather fruits and vegetables. And she could easily dash from predators to safe places high above the ground. But as our forebears began to walk along the ground beneath the trees and out onto the open plains, as well as carry sticks and stones to harvest dinner, I think females became overburdened.

How could a young mother dig for roots and catch small animals with one arm while she carried a squirming, twenty-pound infant in the other? How could she sprint away from hungry lions that licked their chops as she toted armloads of bulky things? I believe these early females began to need mates to help feed and protect them—at least while they carried and nursed a child.