Why We Love (18 page)

Read Why We Love Online

Authors: Helen Fisher

BOOK: Why We Love
9.83Mb size Format: txt, pdf, ePub

As pair-bonding became essential to females, it became suitable to males. How could a male protect and provide for a harem of females? Even if he succeeded in attracting a flock of women, other males would join his group to woo them, perhaps even steal away with one or more. But a male could provision and safeguard a single female and their nursing child.

So as our forebears adopted life on the dangerous ground, pair-bonding became imperative for females and practical for males. And monogamy—the human habit of forming a pair-bond with one individual at a time—evolved.
2

We have some evidence that monogamy evolved long ago. Recently the bones of men and women living some 3.5 million years ago and known as
Australopithecus afarensis
were remeasured for skeletal size. As it turns out, males were somewhat larger than females; in fact the sexes varied from each other in roughly the same proportions that modern men and women vary. Anthropologists regularly use size differences between the sexes of a species to gauge what sort of social group they lived in. And this size difference suggests these early relatives lived in the same sort of social units we do today: they were “principally monogamous.”
3

Scientists have even found genetic evidence of ancestral monogamy. Remember prairie voles, those mouselike creatures that form pair-bonds soon after puberty and settle into a lifetime of burrowing with a spouse? Neuroscientist Tom Insel and his colleagues discovered in these animals an
extra
bit of DNA in the gene that controls for the distribution of vasopressin receptors in the brain, a bit of DNA not present in their promiscuous, asocial cousins, montane voles. These scientists took this tiny piece of DNA out of prairie voles and inserted it into some highly promiscuous male mice. Sure enough, these mice began to form close monogamous relationships with particular females.
4

Humans have a similar gene that codes for the activities of vasopressin. And some people (but not all) carry this same extra bit of DNA on this gene.
5
Someday we will know exactly what this genetic region does in people and why some carry it and others don’t. For the moment we can say this: long, long ago humanity must have needed to pair up to rear their young—because at least one gene that codes for monogamous behaviors is embedded in our DNA.

“Two are better than one,” the Bible says.
6
I think our forebears understood this aphorism more than 3.5 million years ago.

Evolution of Divorce

But I don’t see why these primordial pair-bonds needed to be permanent. Everywhere in the world where people are permitted to divorce (and economically can divorce), many do. If you ask them why they terminate a union, each gives a different reason. Yet human parting has some patterns—and some of this blueprint appears to have evolved in the cradle of humankind.

I arrived at this conclusion while I was gathering divorce data on fifty-eight diverse human societies recorded in the Demographic Yearbooks of the United Nations.
7
I found several surprising worldwide patterns to human separation. There were many exceptions, of course. But as a rule, couples around the world who divorced, tended to part during and around the
fourth
year of marriage, in their middle twenties and/or with a single dependent child.

At first these patterns were meaningless to me. But as I read about the mating habits of other creatures, I began to see some uncanny parallels.

Only 3 percent of mammals pair up to rear their young; humans are among them; but this habit only occurs under special circumstances. Among these: female mammals form a pair-bond when they cannot rear their infants by themselves.

Such are foxes. The dog fox and the vixen form a pair-bond in mid-February, build several dens, and rear their kits together. They do this because the female bears as many as five exceedingly helpless kits; they are born blind and deaf. And the female’s milk is so thin that she must remain in the den almost constantly to feed her young. She will starve unless someone feeds her. So she and a “special” friend form a pair-bond and rear their young together. As the kits wander from the den in high summer, however, parents depart—separately. Their work is done. Next year the couple may reunite; more likely each will take a different mate.

Serial monogamy is common among our feathered friends. The robins that grace our parks each spring pair up for the breeding season. They, too, must divide their duties. Someone must incubate the eggs, then protect the chicks; the other must provide dinner for the family. Successful couples raise several broods. But when the last of the fledglings wing away, parents part. Next year, many will take new spouses.

So, in those species that pair up to rear their babies, many remain together only long enough to raise the young through infancy.

This principle also seems to apply to people. In traditional societies, the lifeway of habitual exercise, a lean diet, and low body weight coupled with the habit of nursing an infant for extended periods around the clock inhibits regular ovulation for several years after childbirth. Among these societies are the !Kung Bushmen of southern Africa, the Australian Aborigines, the Gainj of New Guinea, the Yanomamo of Amazonia, and the Netsilik Eskimos; women in these cultures tend to bear their young about four years apart. As a result, anthropologists think that four-year birth intervals were the regular pattern of birth spacing during our long human prehistory.
8

Thus the duration of human birth spacing is similar to the general duration of worldwide marriages that end in divorce.

So here’s my theory: perhaps like robins, foxes, and many other serially monogamous creatures, ancestral humans living some 3.5 million years ago paired with a mate
only long enough to rear a single child through infancy—about four years.
9
When a mother no longer needed to nurse or carry an infant constantly and could deposit her baby with grandmother, aunts, sisters, cousins, and older youngsters while she gathered food, she no longer needed a full-time partner to ensure the survival of her child. Indeed she could “divorce” a mate if she found a new man more to her liking. Primitive divorce even had genetic payoffs: men and women who “remarried” could bear young with a different partner—creating beneficial variety in their lineages.

“Trouble is only opportunity in working clothes,” wrote industrialist Henry J. Kaiser. As serial monogamy evolved over countless generations, I think this habitual human practice selected for the brain circuitry for short-term attachment. Along with this remarkable innovation came our human concepts of the “father,” the “husband,” and the nuclear family, our human tendency to become restless in long relationships, and our human penchant to depart a relationship and pair again: serial monogamy.

But did this primitive tendency to form short-term partnerships spark the development of human romantic love?

Perhaps it did. Perhaps the attraction that chimps and other creatures feel for a “special” mating partner became more intense and enduring as primitive men and women began to pair up to rear infants as a team. Then as this attraction slowly ebbed, feelings of intense attachment grew. When their child toddled out of infancy, however, I think many couples began to seek fresh love. A few parents may have remained together to have more children; many others sought new romance—unconsciously driven to bear more varied young.

But the courtship process must have been rather simple some 3.5 million years ago. I say this because these australopithecines had a cranial capacity of some 420 cubic centimeters, only slightly larger than the average cranial capacity of chimps. And impressions left by brain tissue on the inside of these fossil skulls indicate that the regions for human language had not begun to grow. They did not speak in human ways. Moreover, these forebears left no drawings on rock walls, no homemade flutes or drums. They didn’t even make flint knives or any other kinds of stone tools for hunting—a hallmark of humankind. Our forebears had not developed the linguistic flair or other courtship tools humanity would come to flaunt. And it was in tandem with the evolution of all these magnificent human talents for wooing that I think human romantic love would bloom.

To court, these australopithecine forebears must have depended on their status in the group, their chimplike wits and charm. They probably felt deep attraction to a mate, even remained attached to a mating partner for a few years. But many went on to court and love anew.

“O Brave New World”

The brave new world of humanness that Miranda wondered at in Shakespeare’s
The Tempest
started to appear some 2 million years ago. New people had begun to wander the open plains of what is today Kenya and Tanzania—
Homo habilis
, or handy man.

Archaeologists have found heaps of their unfinished stone tools scattered across the plains of East Africa.
10
Generation after generation of
Homo habilis
peoples must have come to these quarry sites to make hammerstones, knives, anvils, and other tools, leaving behind slivers of flint and lumps of unfinished lava, obsidian, quartzite, and limestone. They weren’t highly skilled. They only whacked off one or two sides of rocks to create a sharpened edge or point. But these implements were far superior to those made by any other creature living at the time.

Our
habilis
forebears also assembled at what appear to be meat-processing places. Here they lugged huge hunks of hunted game, then sat and stripped the bones of meat, removed the marrow and the fat, and shared and ate. Some twenty-five hundred tools and animal bones were found in these ancient garbage dumps. These ancestors evidently hunted an assortment of large animals, too. Primitive zebras, horses, pigs, monkeys, gazelles, and many other types of antelope were their prey. And because these animals are too big to be consumed alone, our kin must have shared their spoils according to social rules.

They also left what could be evidence of romantic love.

Some of these hunters left dozens of stone tools around a fallen elephant. All its bones remain except its tusks and toes. Did they remove these appendages to use as amulets for luck in hunting—or in love? Did these hunters give away these trophies to impress “special” girls instead?

I suggest these possibilities because these people were getting smarter. One
Homo habilis
individual who lived some 1.8 million years ago in what is now the badlands of Koobi Fora, Kenya, had a brain capacity of some 775 cubic centimeters. His friends and neighbors had an average cranial capacity of some 630 cubic centimeters. Equally remarkable, one skull dated 1.8 million years ago had an indentation on its inner side to accommodate a brain region we now call Broca’s area. Humans use this brain region to form words and produce the sounds of human language.

Talking. There have been so many different theories on the evolution of human language that as long ago as 1866 the Linguistic Society of Paris announced it would accept no more articles on this topic. That declaration has deterred almost no one since. I won’t offer another elaborate theory. Nevertheless, as Broca’s area started to take a human shape by 1.8 million years ago, it seems reasonable to believe that some of our forebears were beginning to speak with some sort of primitive human tongue.

One can certainly see many purposes for language. With meaningless noises arranged and rearranged to make words, with words strung grammatically together to make sentences,
Homo habilis
men and women could frame arguments, strike deals, support leaders, dupe foes, teach skills, scold cheaters, spread news, set rules, stop tears, define kin, placate gods, and recall events that occurred years ago.

The first human conversations were probably about the weather. I say this because I am constantly amazed at how earnestly and repeatedly people converse on this matter. Unquestionably our forebears also discussed which way the zebras went, the cliffs where the baboons congregate at dusk, the ripe melons near the canyon edge, and why Mara’s little baby cries at night. They probably expressed hundreds of other thoughts and feelings about today, yesterday, and tomorrow.

But with words they could also woo. Men and women could tell clever stories, chant sexy tunes, and entice would-be lovers with insightful thoughts. With words, our forebears could flatter, tempt, and tease. They could gossip, reminisce, and whisper with a beloved, too. As primitive human language gradually emerged, our forebears must have begun our endless human chat about, and with, “him” and “her.”

It is at this general time in human evolution that I feel the brain circuitry for animal attraction developed into its human form: romantic love. I propose this for a series of related reasons.

Nariokotome Boy

A boy died. His bones sank into the mud of a swamp some 1.6 million years ago in what today is Kenya. In 1984, paleoanthropologists retrieved almost all of his fossilized remains.
11
When they reassembled his bones and teeth, they gazed upon a child who was somewhere between the ages of eight and twelve. He looked unnervingly like you and me.

Nariokotome Boy, as anthropologists call this stunning fossil find, might have stood over six feet tall had he lived to adulthood. His hands, arms, hips, and legs were similar to ours. In fact, had he worn a mask, he could have walked along any street today without notice. Had he removed his headgear, however, we would have gasped. Nariokotome Boy had thick brow ridges above his eyes. His forehead was low and sloped. His face protruded. His teeth were big. And he had no chin.

Yet he and his
Homo erectus
relatives had evolved in many ways. These people made fancy tools, known as Acheulean hand axes. Some were almond-shaped, others looked like a pear or teardrop; many were seventeen inches from tapered tip to rounded butt; and all were well balanced and quite symmetrical. These folk had conventions for making tools and weapons. And they left thousands of their streamlined hand axes, as well as an enormous variety of cleavers, picks, and knives, along the bogs, marshes, lakes, streams, and rivers of East Africa. They were hunters.

Other books

Cipher by Robert Stohn
Death of a Mystery Writer by Robert Barnard
The Hybrid by Lauren Shelton
Acknowledgments by Martin Edwards
The Proud Wife by Kate Walker
Steeplechase by Jane Langton
Kane: An Assassin's Love Story by Saxton, R.E., Tunstall, Kit