Why We Love (19 page)

They felled huge creatures, too. They left hundreds of tools around the skeletons of hippos, elephants, buffalo, and zebras. To track, surround, and kill these beasts, they needed acute spatial skills. To parcel out their booty, they needed memory of their obligations and advanced linguistic skills. To appease, impress, coordinate, and cooperate as a group they must have needed humor, compassion, and many other executive social skills as well.
Homo erectus
men and women were becoming human.

Nariokotome Boy and his relatives also harnessed fire.

Not the computer, the printing press, the steam engine, or the wheel would transform humanity as did this basic technological development: controlling flame.

With fire they could harden points on spears, smoke small mammals from their burrows, drive elephants into bogs, steal a lion’s supper, and frighten all sorts of creatures from their caves—and then move in. The sick, the young, the old could lounge in camp. They were able to maintain a camp. And they could extend the day into the night, talk around the flame, and sleep in its protective glow. Unchained from the circadian rhythms of all other animals, these forebears had time to sing and dance, propitiate unknown forces, mull over yesterday, decide about tomorrow—and explore beyond the horizon to the north.

Explore they did. Carrying burning embers, our
Homo erectus
ancestors moved out of Africa to explore colder climes, in part because they could. Some 1.8 million years ago the earth’s temperature plunged, beginning the Glacial Ages. Periodically mountains of ice would suck up ocean waters and the world sea level would drop over three hundred feet, leaving wide land highways out of Africa. The big herd animals headed north to pastures fresh and new.
Homo erectus
families followed—leaving their bones and tools in far-flung Europe, China, and Java more than a million years ago.

Brain Power

Of all the gifts bestowed by flame, however, perhaps the most remarkable was humankind’s new ability to cook food. I think this innovation contributed considerably to the evolution of human romantic love.

Cooking meat hastens the release of amino acids that aid digestion.
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Cooking vegetables destroys toxins. And cooking any food devastates microorganisms that can take up residence in the gut and kill. Cooking helped Nariokotome Boy and his relatives survive and thrive.

But cooking also spurred the evolution of the human brain, for an interesting reason. Animals must expend a great deal of metabolic energy to build and maintain their heart, liver, kidneys, stomach, and intestines. They must expend even more energy to build and feed their brain. So animals must allocate their resources. And because creatures that eat mainly leaves must devote a huge amount of energy to their digestive organs, they cannot support a complex brain as well.
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Those who eat meat, however, have extra fuel to allot to brain power.

Homo erectus
did just that. Nariokotome Boy had a cranial capacity of approximately 880 cubic centimeters. And some of his relatives had brain volumes as big as 1,000 cubic centimeters, not too much smaller than the modern human cranial capacity of about 1,325 cubic centimeters.

What an investment. While the human brain is only 2 percent of our body weight, it consumes 25 percent of our metabolic energy and 40 percent of our blood glucose as food. Thousands of genes, indeed one-third of our genome, direct its development. During their first year infants spend 50 percent of their metabolic energy just constructing and refining brain mechanisms.
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Moreover, the slightest mistake in these processes can seriously impair brain function. So the evolving
Homo erectus
brain was exceedingly costly, as well as highly vulnerable to mutations and poor engineering.

This magnificent organ
must
have served crucial purposes: among them may have been to impress potential mating partners with new types of linguistic, artistic, moralistic, or other forms of seductive flair.

Bigger brains would cause trouble for women, however—an obstetrical dilemma that I believe spurred the evolution of romantic love.

The Obstetrical Dilemma

How could
Homo erectus
women bear big-headed babies through their little birth canals? The size of the human pelvis must retain its basic shape to enable upright walking. So as the infant’s head increased in size, ancestral women became obliged to deliver their infants in an
earlier
state of development. Anthropologists think this “obstetrical dilemma” began to occur by the time the adult human cranial capacity had reached about 800 cubic centimeters—during
Homo erectus
times.

Many women must have died as they tried to deliver their bigheaded young. But nature likes variety, and some fortunate females must have been able to give birth to their infants in an earlier stage of growth. These babies lived. And rapidly our forebears evolved a hallmark of our species: exceedingly helpless, undeveloped infants.

With this remarkable evolutionary development,
Homo erectus
women must have felt overwhelmed by the job of parenting.

To make matters worse for mothers, childhood almost doubled. Chimpanzees complete puberty around age ten; we humans don’t complete our growth until around age eighteen. And unlike chimps who begin to feed themselves around age four, human children depend on adults until the late teenage years. This phenomenon is known as “delayed maturation.” Anthropologists believe it first developed in
Homo erectus
times.
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What a burden—small, weak, needy infants who often remained boisterous, willful, unskilled, and hungry for almost twenty years.

With the origin of big-game hunting, fancy tools and weapons, the harnessing of fire, our growing brains, our tiny helpless babies, our long teenagehood, and our march from Africa into chilly, dangerous northern worlds, our ancestors must have felt intense pressure to find mates they could live with for longer periods of time. Parenting had become far too much for one.

With these developments I believe courtship intensified. Individuals needed to distinguish themselves in new and special ways to attract mates with whom they were genuinely compatible. Men and women had already begun to develop a modicum of verbal ability, artistic verve, humor, inventiveness, courage, and many other human gifts in order to survive on the open plains, as well as the brain circuitry to appreciate these skills in others. Now suitors increasingly used these talents to display their usefulness and good genes to potential lovers, too. Those being wooed responded, due to their preexisting preference for these skills.
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With this greater need to seek and choose a
long-term
partner, I think the brain circuitry for human romantic love emerged.

Evolution of Human Romantic Love

The process was probably rather simple. A million years ago, some ancestors excelled at clever remarks or charismatic speeches; others were good at athletic feats. The forerunners of our modern journalists kept track of the group’s doings; they impressed potential mates with news and gossip. The first poets charmed their admirers with rhythmic tales. The ancestors of Rembrandt and Matisse drew better pictures in the dirt. And the forerunners of our rock stars and opera divas swayed potential lovers by singing tribal myths. Some cured the sick. Some communed with the spirits of the wind and night. Some were daring; some extraordinarily generous. Others made their sweethearts laugh. “When a man makes her laugh, a woman feels protected,” wrote Ugo Betti.
Homo erectus
women must have adored witty fellows—and joined them in the bushes on idle afternoons.

In those demanding days of yesteryear, our forebears came to need more and more special talents to entice potential mates into long-term partnerships. Those who excelled at complex forms of language, art, or song survived and bred—passing these and many other exquisite human talents along to us. But each man and woman “advertised within their budget,” because each had a limited amount of metabolic energy and brain circuitry to expend.
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Suitors therefore specialized—and displayed their special wares to catch a mate.

This courting process continues. Einstein once asserted that “a person who has not made his great contribution to science before the age of 30 will never do so.” Although all of us can list men and women who excelled later in life, Dr. Satoshi Kanazawa of the London School of Economics recently confirmed Einstein’s statement and offered a Darwinian explanation. After studying 280 great male scientists, he confirmed that 65 percent of them made their biggest discoveries before age thirty-five. He also noted that most lost their creative drive after a few years of marriage. Kanazawa concludes that these young geniuses were “seeking to impress women with their virtuosity.”
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I think young
Homo erectus
men (and women) were seeking to impress potential mates with their virtuosity more than a million years ago.

More important to our story: as suitors displayed their various special talents, those
viewing
these courtship ploys began to need advanced reasoning, judgment, insight, memory, awareness, consciousness, self-consciousness, and many other sophisticated brain mechanisms to distinguish among courters.

They also needed the brain circuitry to appreciate these courtship displays. They needed to relish morality, admire religious fervor, treasure novelty, esteem clever poems and touching rhythms, delight in good conversation, cherish honesty, applaud determination, and value myriad other aptitudes. They had to evolve the brain power to detect fakers. And they surely needed to develop brain mechanisms to decipher what potential lovers were thinking. Called “theory of mind,” this ability to understand the mental states of others, their desires and intentions,
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is particularly well developed in humans.
Homo erectus
men and women needed the mental machinery to assess personality and accomplishment in order to appraise and value their suitors a million years ago.

They also needed a mighty biological urge to drive them to focus their courtship energy on a specific mating partner, an urge so potent they would be willing to make a long-term commitment to this special individual, even die for “him” or “her.”

“What does not destroy me, makes me strong,” wrote Friedrich Nietzsche. Among
Homo erectus
people, the vicissitudes of childbirth and delayed maturation spurred the need for long-term pair-bonds and greater courtship ingenuity. And this courtship pressure gave rise to our extraordinarily fancy human aptitudes, our human mental machinery to appreciate these talents, and the brain circuitry for romantic love—the passion to drive the “courter” and the “courted” to make a deep commitment to rear their young together for years and years.

“O, I willingly stake all for you,” declared Walt Whitman. Men and women needed to say these words over a million years ago.

The Mind Evolved by Daylight

Of course, our
Homo erectus
forebears had other vital reasons to develop uniquely human capacities. Nariokotome Boy and his relatives needed to feel empathy for a wounded comrade, patience for a cranky child, understanding for a disgruntled teen, and to develop the social graces to get along with obstreperous or pompous members of the group. They were a band. They had to move together through the grass, a killing field for predators. So those who could perceive dangers, remember past calamities, devise strategies, articulate choices, make decisions, judge distances, foresee obstacles, and persuade comrades with convincing postures and compelling words disproportionately survived. The human mind evolved by daylight.

But after dark they must have assembled around the firelight to roast their meat, sharpen spears, rock their cooing infants, and imitate the ostrich, hog, or panther as the old folks slept. They must have sung of courage, fortitude, and conquest, leapt and wrestled to show endurance, wept to show compassion, and clowned to parade their wit. Many also slipped away to cuddle. By moonlight, our outstanding aptitudes also took their human shape.

Marching toward Modernity

As time passed, our forebears left increasing evidence of their courting life. By 500,000 years ago, someone in what is now Ethiopia had a brain volume of roughly 1,300 cubic centimeters, within the modern human range. He or she certainly had a complex brain—and a mind capable of passionate romantic love.

About 250,000 years ago, a man living in what we know as England meticulously chipped a symmetrical hand axe around a fossil shell he had found embedded in a lump of flint. Perhaps it was a gift to a beloved or an advertisement to show a lover his tool-making prowess. In fact, scientists now maintain that the huge seventeen-inch hand axes our forebears chipped for over a million years were too big to serve on the hunt or to gather vegetables or roots. Because many are unwieldy and meticulously fashioned, they may well have been used to impress and woo.
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Sixty thousand years ago people living in the Zagros Mountains of northeastern Iraq buried someone in a shallow grave one June day and covered the corpse with hollyhocks, grape hyacinth, bachelor’s buttons, and yellow flowering groundsel. Perhaps one of them yearned to see a beloved one in an afterlife. At this same time, someone in France scraped lumps of hematite and manganese to make earthy red and gray-white powders. With these, a woman may have decorated her hips and breasts for a summer dance.

By thirty thousand years ago, Cro-Magnon people sported totally modern human skulls, as well as brains like yours and mine. Now they would decorate just about everything they touched. Skilled artists descended into huge caverns beneath France and Spain to draw magnificent bulls, reindeer, ibexes, rhinos, lions, bears, and magical beasts on dank cave walls. These black, red, and yellow creatures pound along these grottos with such vigor they almost come alive. Breaking the utter silence of these vaults, musicians played flutes and drums. Hundreds stenciled their handprints on craggy walls. Sculptors left behind small bison of fired clay. And footprints in some caverns still tell of those who danced in the flickering light of oil lamps.