9

LOVE

OF ALL LOVE stories, the Celtic saga of Tristan and Isolde is probably the most uncompromising. Although Isolde had wanted to exact a cruel vengeance on Tristan for having killed her betrothed, his gaze mollifies her and her hatred is transformed into attraction. When her maid inadvertently pours them a love potion, the two can no longer resist their passion. Nothing matters but that they be together. In their ecstasy, they’re even willing to betray her husband (and his uncle), good King Mark. When their affair is discovered, they choose to die together.

Why did they go so far? “I am unable to tell you this,” answers Tristan in Wagner’s opera when he’s questioned by the shaken Mark. He doesn’t understand the power that has taken hold of him. But the music that Wagner composed for this scene reveals more: a longing that can’t be put into words, a feeling that is both torment and ecstasy.

This is an experience familiar to everyone, even if, fortunately, the longing only rarely becomes as absolute as in the saga of Tristan and Isolde. We feel that love casts a spell over us and that we are possessed by it. But what has transformed us, and why it was this person who has become so all-important . . . we simply don’t know. So it shouldn’t surprise us that in times past, such an overpowering force—one that made people fall in love even against the dictates of their reason—could only be explained as fate, or magic.

THE ELIXIRS OF LOVE

But there are indeed love potions, and in ascribing attraction’s power to them, the Celtic bards were much closer to the truth than they could have known.

There is, for example, the hormone luliberin that is normally created in the hypothalamus and that controls the release of sex hormones. When even the tiniest quantity of this substance is present in the midbrain, it sets off uncontrolled desire. When it was administered experimentally to male guinea pigs, they immediately began to engage in energetic sexual play with any females who happened to be near them. And the females under the influence of this substance were willing partners.1 Luliberin works exactly the same way in humans, though it’s not especially useful as an aphrodisiac, since the extra dose would have to be injected directly into the brain.

Such experiments may be distasteful, because they make sex seem totally mechanical. But the elixirs of love do much more than stimulate a readiness for sex—they can help two people to develop a mutual devotion that endures all their lives. This phenomenon was studied by Emory University’s Tom Insel on the prairie vole, a wooly little animal native to North America that he injected with the hormone vasopressin. The result: from then on, they never left their partner’s side. The females accomplished the same feat when given a closely related substance, oxytocin.

In fact, Insel had only accelerated a process that would have occurred anyway, for the prairie vole enjoys a most unusual love life. As soon as these finger-long creatures reach maturity, they lunge for the first available sex partner. They give themselves over to love for an entire day, the male mounting his companion up to two dozen times. From then on the two stay together forever. They move into a shared nest, he becomes a caring father to their offspring, and when an intruder approaches, the two partners defend one another and their home. Being separated has no effect on their bond, for even months later they still recognize and desire one another. This fidelity transcends even death: When one of the partners dies, the survivor remains single.

How does such a strong attachment come to pass? While copulating, the males produce vasopressin, the females, oxytocin, and these hormones affect the brain in such a way that the two partners develop a preference for one another. Sex prepares the way for love.

It was this process in which Insel intervened. When he injected the male and female prairie voles with the appropriate hormones, they became lifelong mates even if they hadn’t first spent a night of passionate lovemaking together. A single substance sufficed to create a bond for their rest of their lives. And the experiment also worked in the opposite direction. When, after a night of lusty sex, the animals’ love hormone was blocked, there was none of the monogamy otherwise characteristic of the prairie vole.

This lack of fidelity is apparently caused by the partners’ forgetting one another, or even failing to leave much of an impression in the first place. In any case, when a prairie vole with a nonfunctioning vasopressin system is confronted with a female with which he’s often had sex, he behaves as if he’d never met her, sniffing her each time as if it’s their first encounter. Tests showed that the problem wasn’t that he’d become more stupid, but rather that he’d lost his memory for other creatures. Partnership relies on social memory, for which the brain apparently has dedicated circuits that are affected by oxytocin and vasopressin. When we think longingly of our beloved, these are the chemicals whose effect we’re feeling.2

Vasopressin and oxytocin create partnerships even among animals to whom such relationships are otherwise entirely alien. House mice, for example, are normally interested in their partners for the duration of sex, and that’s it. Using genetic intervention, Insel taught them monogamy. Planting a single gene from the prairie vole into their genetic material and thus equipping their brains with receptors for vasopressin and oxtytocin, he made faithful partners out of the house mice. House mice, too, produce copious quantities of these hormones during sex, but because there are no suitable receptors in their brains, they have no lasting impact. After the tiny genetic reconstruction, however, vasopressin and oxytocin make it possible for these animals to enjoy a durable partnership. It takes only one single gene to change a polygamous animal into one that is monogamous and set the stage for all the intricate behavioral patterns that a lifelong partnership requires.3

With humans, the mechanisms of attraction, love, and fidelity are more complicated. We, too, are predisposed toward monogamy, though we could hardly claim that every steamy night leads to a lifelong relationship. But it would be surprising indeed if “love potions” did not play a crucial role in humans. For five hundred million years oxytocin, vasopressin, and similar substances have governed the sexual lives of almost all creatures, from the simplest earthworms to our nearest relatives, the apes.4

What distinguishes us from these creatures isn’t so much the basic mechanisms of love but rather the freedom that we have in dealing with them. People can give themselves over to their inclinations, in extreme cases even against their better judgment—as in the finale of Wagner’s opera Tristan and Isolde, when the exhausted Tristan curses the “terrible potion” and suggests with the words “I brewed it myself” the deeper truth: It is a product of his own mind. Real people, too, can resist love, whether because of family opposition, or because they’d rather put their time and energy into their careers.

Our environment has a major influence on whether, when, and how we bond with other people. But the emotions on which this is all based are programmed into us.5

WOMEN’S BRAINS, MEN’S BRAINS

The attraction between the sexes begins in the brain, which is structured differently in men and women in order to ensure mutual appeal. The stage for sexual desire is set in the uterus.

A fascinating experiment undertaken by nature itself shows how the female and male poles of love come into being. It concerns a small group of villagers in the Dominican Republic who are called guevedoces, Spanish for “balls at twelve years of age.” In the course of their maturation, the guevedoces seem to undergo a sex change. At birth there is no sign of scrotum or penis, and so, looking like girls, guevedoces are raised as girls. As soon as the hormonal changes of puberty set in, their true sex emerges: the scrotum descends from what were presumed to be labia and from the clitoris grows a penis. At the same time, the guevedoces begin to behave like young men. From one day to the next they throw the dolls and clothes that they grew up with into the corner, don shirts and pants, and begin to show interest in soccer—and especially in girls.

In the traditional world of their villages, where every fifth child can be a guevedoce, it ceases to matter that they were raised to be courted by men. They now respond to female charms, and quite reflexively. So powerful is love’s genetic programming and so small the influence of their upbringing. These brand-new men have no difficulty settling into their role—they just do what nature demands of them.

Like the body, the brain is built according to a design, which is either male or female. This is set in the first weeks of pregnancy, when the fetus’s brain and sex organs develop, according to either the male or the female model. Thus, a child comes into the world with the brain of a boy or a girl, and with the corresponding appearance.

But the guevedoces, whose puzzle was solved by American scientists over two decades ago, are different: of the two switches (one for the brain and one for the body), one is damaged. Although the fetus’s brain develops normally, the formation of the sexual organs is delayed, and the guevedoces are born with a boy’s brain and a girl’s physical appearance. This unique phenomenon shows how strongly the prenatal structure of the brain determines later behavior in love.6

But why are they pseudofemales who become boys rather than the other way around? At the beginning of development every human is female. The basic architecture of body and brain from which both sexes develop is that of a woman—the opposite of the story of Eve being created from Adam’s rib. Only later does the male Y-chromosome give the signal for male development. At about eight weeks after conception genes on this chromosome spur the gonads to produce testosterone, the male sex hormone. Using various signal paths, this transmitter instructs body and brain that a male is on the way.

Differences between the sexes are particularly apparent in the structure of the cerebrum. In women, the two halves are more strongly connected, which is why the individual brain centers seem to be somewhat less specialized than in men. It has often been surmised, but never proven, that for this reason women are usually more willing than men to speak about their feelings. What is certain is that the slightly different organization of female and male brains is expressed in thinking. Women are usually more fluent in speech and quicker in mental arithmetic and in their perceptions, and they are often more skilled with their hands. Men, on the other hand, are often better at mathematical-logical thought and spatial conceptualization.

In general, however, the significance of these differences is grossly exaggerated. A catchy title like Why Men Don’t Listen and Women Can’t Read Maps, for example, tries to suggest that all kinds of discrepancies between the sexes can be explained simply. But it isn’t that simple. That the two sexes have different strengths is a matter of averages—from data that was gathered among very many men and very many women. And statistics have to be interpreted with care, especially when, by and large, the differences aren’t that great. On average, the sun shines over New York 107 days per year, and over Baltimore only 105 days. Nonetheless, one would never claim that on a daily basis New York has better weather than Baltimore.

HOW SEX GETS INTO OUR HEADS

The differences between the brains of men and women are fairly small when it comes to thinking, but in matters of love, they’re huge. The lives of the guevedoces suggest that the brains of heterosexual men and women are as good as programmed toward the opposite sex. And in recent years, brain researchers have begun to discover the roots of sexual preferences.

The source of sexual attraction is the diencephalon, which lies exactly in the center of the brain and where the conditions for arousal are created. It differs so strongly in men and women that it’s possible to distinguish a female from a male brain with the naked eye: A particular nucleus, the medial preoptic area of the hypothalamus, is twice as big in men’s heads as in women’s, and it is also constructed differently.7 Among other things, the preoptic area controls the release of luliberin, which is so important.

We see the consequences of size difference in love play, for in all likelihood the preoptic area in men serves to stimulate their desire for women. If this nucleus is stimulated, an almost fanatic enthusiasm develops for anything female that comes into view. If it’s removed, interest in the other sex wanes. Male monkeys whose preoptic area has been surgically removed begin to behave like females, although they continue to practice and enjoy masturbation. This suggests that different processes are responsible for developing interest in the opposite sex and getting sexual satisfaction.8

A group working with the Japanese neurologist Yutaka Oomura has studied the preoptic area very closely. In order to let attraction and sex run their course under controlled conditions, they came up with a rather remarkable arrangement involving subjects who copulated in chairs on tracks, during which scientists measured the neuronal activity in the hypothalamus. All this would seem more appropriate in the sex bars of Bangkok than in a university laboratory, although the “subjects” weren’t humans but macaque monkeys, and you will be reassured to hear that the experiment involved no pain for the animals.9 Still, the bizarre experiment provided the clearest proof to date that the preoptic area is, above all, responsible for sexual desire and not for the sex act as such.10 Just how it fulfills its task is not yet fully understood. Probably electric connections to the penis and the cerebrum are formed from other nuclei in the midbrain and the nervous system. Many researchers suspect that the brain’s anatomy helps explain the frequent accompaniment of masculine sexuality with aggression. The preoptic area is connected by several fiber bundles to the amygdala—the center releases that aggression, along with other dark feelings.11

With female desire—much less well researched—another area in the midbrain occupies the key position, the so-called ventromedial nucleus of the hypothalamus. In mammals, it releases the mating reflex. Female rats become still so that the males can mount them, and female monkeys present their sex organs. With human females, who aren’t bound by such ritual behaviors, the ventromedial nucleus probably stimulates only a general willingness for sex. This nucleus is under the influence of the sex hormones, which is a possible explanation for the variability in women’s ability to be stimulated during the course of their monthly cycle.

A quick look at the brain shows the extent to which women, too, are programmed for sex, for in both sexes large areas under the skull are generously equipped with receptors for sex hormones like oxytocin. That an overwhelming number of neurons are busy receiving signals from the sex organs and transforming them into feelings of love has a good reason. If the size of individual organs were commensurate with the space given them in the brain, the penis and the vagina could easily outweigh the entire upper body. Next place would go to the lips, also organs designed for the enjoyment of love (as well as nourishment).

VARIETIES OF LOVE

For a woman to love a man, and a man to love a woman, isn’t everyone’s idea of fulfillment: at least seven million people in the United States prefer a partner of their own sex.

In no way does this fact contradict the discoveries about the sexual formation of the brain. The guevedoces, with their transformation from pseudogirls to men, are another example of the freedom that biology gives to variety in sexuality. The body’s sexuality and the regions of the brain that control sexual desire can take different courses, and brains frequently develop in male bodies that allow a man to be attracted to other men.

This finding was confirmed by the California scientist Simon LeVay, when he performed autopsies on homosexual men who had died of AIDS. In some characteristics that are consistent with sexual preference, the structure of their brains was more like that of females than of typical males. As LeVay reported, the preoptic area was smaller than in the average male (and the links between the two halves of the cerebrum were correspondingly stronger). This certainly doesn’t mean that gay men have women’s brains, as is often claimed. The differences involve the regions for sexual desire almost exclusively. In brain volume, on the other hand, which is markedly different for men and women, there was no difference between homosexuals and heterosexuals.

Homosexual organizations were extremely critical of LeVay, himself openly gay. The activists were afraid that they would again be stigmatized as “sick” if their sexual preference could be shown to have an organic basis in the brain.12

This kind of mistrust by a minority that has been struggling for its rights is understandable. But their concerns miss the heart of the matter. In reality, LeVay’s studies show how normal homosexuality is: when men feel passion for other men, it’s in no way deviant, but simply a natural variant of orientation. Just as there are right- and left-handed people, and people who are gifted in music, and others in sports, there are also different predispositions in sexuality. The same is certainly true for women, although lesbian love, like so many other specifically female matters, has so far not gotten much attention from researchers.

Between homosexuality and heterosexuality lies a whole range of intermediary steps. Only rarely does a brain develop to the extremes of the masculine/feminine spectrum. Much more often, it is somewhere in between. No one is entirely male, no one entirely female.

The subtlety of these shadings can be observed in mice, whose adult behavior is strongly influenced by the social environment of the womb. A female mouse baby that lies with brothers in her mother’s womb, and is thus exposed to their sex hormones, later behaves more aggressively and (oddly) bears more babies than females who developed only among other females. With male mice we see the opposite effect: sisters in the uterus give them a gentler nature. Clearly, the cause for gender behaviors lies by no means only in the genes—influences before or after birth can play an equally large or even larger role.13

With people, the gradations between the sexes can be still finer, not only because we’re much less bound by a particular role than other creatures (thanks to our larger cerebrum), but also because the male and female poles in Homo sapiens lie very close together. The preoptic area is one piece of evidence for this: it’s almost four times as big in male rodents as in the females, whereas the factor for humans is on average only two. Thus the human brain allows for countless varieties of love, from the shy romantic to the rock-hard dominatrix.

TO CLIMAX

Not every man is a Don Juan. On the other hand, there are few men who haven’t thought of love as conquest and sex as triumph. To some extent, this is a part of our culture, which has been haunted by these motifs for centuries. But it’s not only the qualities of the preoptic area that point to the deeper causes underlying the connection between male eroticism and aggression.

From first laying eyes on each other until climax, men and women experience sexual desire that is governed by different mechanisms. Men are under the influence of the hormone vasopressin. It is not only the tiny prairie vole that is transformed by this substance into a faithful spouse, for in both animals and humans it stimulates aggression. A contradiction? Only at first blush—after all, the father of a family is supposed to defend his wife, child, and home with all means at his disposal.

More than ten times the normal concentration of vasopressin has been measured in men during the different phases of foreplay.14 This number should be viewed with care, because until now it has been found only in the blood, and the hormone levels could be different in the brain, where behavior is determined. That such differences do occur was discovered by the German neurobiologist Rainer Landgraf when he succeeded in measuring the release of oxytocin and vasopressin with a tiny probe directly into the brains of rats.15 The argument could still be made that vasopressin works only in the body and not in the brain at all, but it isn’t very probable, for experiments show that when vasopressin is absent, the male lacks all passion during sex. He’s still capable of the physical act but finds his partner about as exciting as a wet rag.16

The further the foreplay progresses, and the greater the likelihood that it will lead to copulation, the more the vasopressin level drops. At ejaculation it is almost back at the normal level—another indication of how different seduction and sex are. As soon as orgasm is near, another hormone seems to dominate in men: the level of oxytocin, the female counterpart to vasopressin, now rises. Without oxytocin there is no orgasm—and thus at climax both sexes are under the influence of the substance that determined the woman’s desire from the very beginning.

For females take a different path to arousal. If the vasopressin level in the brains of female rats is elevated, their sexual desire drops almost to zero.17 The level of free oxytocin, on the other hand, begins to climb from the first moment of flirting, apparently putting them in the mood for an encounter. If the effect of oxytocin is blocked, they rebuff any male sexual advances. If the males insist, the females become rabid.

As a woman gets closer to climax, ever-increasing quantities of oxytocin are released. During orgasm itself, endorphins are added, which are responsible for orgasm in both sexes. The more oxytocin released during foreplay, the stronger the climax, as scientists who have studied women experiencing multiple orgasms have learned.18

MAKE LOVE, NOT WAR

Why is it that we experience orgasm? This question is as yet without an answer, although scientists have been studying it intensely for decades.

They have been especially intrigued by the riddle of female orgasm. Some even doubt that there is any reason for this unreliable response to exist at all. The interests of reproduction, after all, could be satisfied by hormones that stimulate the females to mate during ovulation. And even if one admits that females should be able to enjoy sex, these researchers think, orgasm would not have to be a precondition for enjoyment. Less radical voices explain that orgasm might serve women as a biological signal that they have found a suitable partner. There is, however, no proof for this rather masculine theory.

At least one myth has collapsed: women, it turns out, are not the only females to experience orgasm. Researchers have observed in female monkeys approaching climax the heightened pulse and uncontrolled movements that are very close to the reactions of a woman during orgasm. The Dutch sex researcher Koos Slob was the first to make this observation in his study of macaque monkeys.19

All primates are social beings, so why shouldn’t mating have a social function beyond procreation? The bonobos, or dwarf chimps, for example, use sex to eliminate conflict. When tensions arise, the most bellicose group members are satisfied sexually. Should the conflict continue, intercourse reconciles the combatants. Since bonobos also engage in same-sex activities, it’s obvious that for them mating has purposes other than just reproduction.

That such activity makes good sense is shown by orgasm’s neurochemistry. Oxytocin, which both sexes release during climax, is a tool for peace. As many experiments confirm, it encourages attachment and militates against aggression. And the opioids, which are responsible for the sense of ecstasy in orgasm, also give a feeling of pleasant relaxation. A person who feels good has little reason to fight.

Sex enables us to get along with one another better, and it can actually diminish aggression and bellicosity. “Make love, not war!” demanded the flower children during the Vietnam era. They were right.

IS LOVE AN ADDICTION?

During love’s most intense moments, one’s partner seems like a very special being. When we’re in love, nothing and no one else can put us is such a euphoric mood. These romantic feelings are often combined with a strange sense of excitement that seems to dissolve the boundaries of the individual. Poets have described this condition since time immemorial. Recently, the London researchers Andreas Bartels and Semir Zeki have shown that the intoxication experienced in love is also accessible to science.

Looking on the Internet for volunteers who described themselves credibly as possessed by “genuine, deep and crazy love,” mainly women, Bartels and Zeki examined their subjects using functional MRI. First they showed the women photos of friends with whom they had no sexual relationship and asked them to think of them intensely. During this time the scientists recorded the activity in their brains. Then they were shown photos of their lovers. While their brains were being examined a second time, they were to think of their partner. Comparing the two experiences, the scientists could see what happens when the brain is focused on the lover, and it turns out to closely resemble the pattern of brains activity under the influence of heroin and cocaine.20

Seen neurobiologically, this is hardly surprising, for drugs and the love elixirs oxytocin and vasopressin affect the same circuits in the brain. Both affect systems in which dopamine, the hormone of desire, plays a critical role. The release of dopamine is necessary in the coming together of two people, for, as we’ve seen, it controls attentiveness and awakens desire.

The neuropsychologist Jaak Penksepp compares love with addiction: in the one case a bond is created with the drug, in the other with a person. This relationship becomes especially evident at separation—withdrawal from the drug and parting from the beloved. Both result in feelings of loneliness and emptiness, in loss of appetite, depression, sleeplessness and irritability.21

The addict usually becomes numb to the pleasant effect of a drug, and over time the attractive qualities of a loved person, too, can sometimes lose their appeal. Nonetheless, we often encounter couples whose eyes shine brightly when they look at one another, even after decades. There must be a mechanism that works against the dulling of love and protects people from experiencing their partner like a drug to which they’re bound only by habit.

Here, too, oxytocin seems to be involved. Animal experiments show that this hormone, at the least, can weaken the habituation to positive feelings. If this proves true, then the magic formula for enduring love is sex. After all, oxytocin is released during sexual climax. Keeping the sense of passion roiling, it might offer couples a kind of fountain of youth.22

THE HAPPINESS OF MOTHERHOOD

Love also blossoms when a child is born. In some ways the affection of parents for their children bears a clear similarity to erotic attraction. People who are in love often feel they’re melding into one another. Mothers and, less often, fathers experience something similar. They feel they’re becoming one with their child and that its pains and joys are their own.

Are the same forces at work in both cases? Brain research makes this seem likely. If we examine the brains of mothers listening to tapes of their babies crying, the images are strikingly similar to those of lovers focused on their partners. This isn’t proof, but it’s a very strong indication that similar processes call forth the euphoria elicited by affection—that feeling of happiness that at its most intense resembles the effects of strong drugs.23

And much as oxytocin plays a role in the attraction between two partners, so it is also present in nurturing love for a child: oxytocin orchestrates all social behaviors. It has been shown in the female brain that before expectant mothers can feel tenderness for their young, they have to undergo a change that oxytocin sets in motion.

This happens in women and, still more dramatically, in the mothers of animals, which, shortly before delivering their young, can be transformed from predators to nurturers. Female rats, for example, normally react to the smell of newborns by eating them—until they themselves give birth. The expectant rat begins to behave more gently even as she builds her nest, and as soon as her young are born she hardly does anything other than nurse the little ones, licking and protecting them.

On the other hand, when scientists block the oxytocin, the mother rat devours its young immediately after giving birth. But oxytocin isn’t enough to stimulate nurturing behavior. In order to get a virgin female to look after baby rats, she first has to be injected with the sex hormone estrogen, which is normally released during pregnancy. Apparently, the brain needs a message from the body that children really are on the way.24

Once the signals for the pregnancy hormones and oxytocin have arrived, the programs for maternal love begin to run in the mother’s head, and certain parts of the female diencephalon are changed forever. Just how this restructuring happens has not yet been fully studied. According to the little that we have learned from animal experiments, it is the preoptic area—a region that is different in males and females from birth—that seems to undergo the greatest change. Apparently certain genes that control the functioning of the gray cells are turned on or off. Thus, the workings of the entire region of the brain can be changed permanently.25

Nor do we yet fully understand whether and in what way nursing permanently strengthens these changes in the young mother. If the female nipples are stimulated, oxytocin is released in the brain, which probably explains the enjoyment women derive from the stroking of their breasts in both lovemaking and nursing. Such feelings create a bond between mother and child, because we reflexively seek to be close to people who have given us a sense of well-being.

In a series of studies at the Karolinska Institut in Sweden, nursing mothers reported a greater interest in other people than before giving birth—also greater than the interest of nonnursing mothers—as well as a greater sense of inner peace. Possibly the oxytocin released during nursing brings forth the experience of social happiness—the joyful sense of being at peace within oneself and being able to give something to others.26

Whatever the effect of nursing, the brain’s restructuring connects most mothers to their children all their lives. The baby’s softest cry will awaken her from the deepest sleep, and a sensitive ear will often hear the cries of children other than her own.

Thus, the brains as well as the bodies of females are designed to have children. Nature rewards them with positive feelings. But not all women get equal pleasure from their children—as with sexual preferences, these gender-related factors differ from one person’s brain to another’s.

We mustn’t forget that fathers, too, enjoy their children. We don’t yet know why, for until now science has concentrated on maternal love. Because men’s and women’s brains are different, the happiness of a father’s love might well be different from a mother’s—but this is still uncharted territory.

DO CHILDREN MAKE PEOPLE HAPPY?

Children bring energy into the house and warm the hearts of their parents. They need us, when they’re in a good mood they beam at us with large eyes, and to follow their development from day to day is one of the greatest experiences imaginable. Many parents say that it was in their children that they found happiness.

All the more surprising are the findings of social scientists on this subject. If, for example, you ask couples how satisfied they are with one another, those who are childless will regularly give themselves a higher score, as four independent studies from Europe and the United States have shown.

In fact, having children diminishes the pleasure that parents find in one another. Over the years, there’s a characteristic up and down in the life satisfaction score that, surprisingly, is similar for mothers and fathers. Happiness in the marriage drops during pregnancy and reaches its first low point when the oldest child is crawling. After that it goes up again somewhat, until the oldest child shows the first signs of puberty, after which it falls quickly to an absolute low point. Apparently teenagers take an even greater toll on their parents’ love for one another than do small children. Children up to school age may exhaust their parents, but it takes an adolescent to push them to their limits. Once the last child is out of the house, the parents’ satisfaction returns to its prechildren level. But if in the course of their marriage, mother and father have gone through the valley of unhappiness, in most cases it isn’t all that deep: on average the level of satisfaction in the children’s teen years is about ten per cent below that of the best years.27

Do children not only fail to bring happiness into marriage but actually make it miserable? Not necessarily. The studies researching the ever-increasing divorce rate looked only at happiness in marriage and not at overall satisfaction. They are closely linked—obviously, marriage has a big influence on general well-being—but not identical. The emotional warmth, the fun, and the feeling of being needed that children give their parents can more than compensate for the burden they sometimes impose on the marriage.

In the end, it’s a standoff. Children make us happy and unhappy at the same time. Happiness isn’t the opposite of unhappiness, and the two aren’t mutually exclusive. And the end result can be very positive. Although having children puts a whole new set of demands on parents, their expectations of life are, on average, higher than among childless adults. This difference is particularly noticeable in the ages 35 to 44. In this age group, less than half as many mothers and fathers die than do people without children—presumably because parents take fewer risks and pay better attention to their health.28

But the bottom line is that the joys and difficulties seem more or less at parity. A new German study comes to the conclusion that, all in all, parents are neither more nor less happy than childless couples. Its implications are especially important given the ever more elaborate techniques of reproductive medicine. Couples who try for their own child with huge effort and considerable physical unpleasantness for the woman should ask themselves whether their expectations might not be greater than is warranted.29

The only measurable impact children have on the parents’ relationship is on the level of satisfaction, and this is negative—in spite of the fantasies most would-be parents have of family life. Because the burden usually isn’t all that terrible, stable partnerships manage to cope easily and accept it as part of the bargain, for children give their lives meaning and color. But they are almost always a test for the relationship, which is why it rarely works when a couple tries to save their troubled marriage—as happens so often—with a baby.