Why Humans Mate

[Adapted from Real Choices, Conciliar Press, 1997]

Glance around any room where people are gathered and a curious pattern emerges: they tend to be in pairs. At a church, a concert, a movie theater, a male head is usually near a female head of roughly the same age. Other creatures gather in herds or flocks, or peel off as solitary loners, but humans prefer the couple bond. They gravitate toward it naturally; it’s how they seem to want to go through life. Why?

We might as well ask a follow-up question: why does this pattern fail? Why has our current culture reached such a high level of divorce and dysfunction? Why is there so much pregnancy outside durable bonds, and so much abortion?

To answer these questions we’ll have to step back to get a longer view. Step *way* back. Imagine a zookeeper on Mars, who has built up a pretty thorough collection of earth mammals.

The Martian zookeeper has noted some interesting things about the residents of the human exhibit. In the first place, compared to other creatures their young are born alarmingly premature. Other mammalian newborns crawl to the mother’s breast and begin to nurse, but if the human baby were not assisted to do this it would starve. The human baby takes a full year just to walk, an age where—even allowing for proportionate life-spans—other mammals are near adulthood. A human newborn looks like it’s not ready to come out yet. But out it comes, and keeping it alive is an exhausting task for a very long time. It appears to be too much work for one parent.

The baby’s ability to communicate in the language of the species is similarly slow to develop. Human parents are markedly more frustrated by inability to interpret their baby’s cries than are bovine or canine mothers. Most mammals rapidly learn to survive without their mother’s care, but a human may take decades of training before he is able to support himself.

The Martian notes that raising a human baby is a lengthy and exhausting process. Unlike the rearing of other mammals, it requires the attention of an adult nearly full-time; without that attention, the species would not survive.

It seems that the female is more suited to this intensive labor of child-rearing, both by temperament and by her ability to nurse—an attribute so vital that it gives the mammalian family its name. Child-rearing is so demanding that she has little time to provide food and shelter for herself, and both mother and child are at risk. The mother’s arms encircle the child, but a second adult is required to add an outer ring of care around those two.

The child’s father seems suited to this role, although not without ambivalence. The early years post-puberty, in particular, propel human males into an exhausting round of compulsive sexual thinking and (attempted) activity that was described by a lustful Hollywood star as “waking up every morning chained to a maniac.” A look at these same males a few years later reveals that most have settled down in monogamous, child-rearing arrangements, although some struggle against a recurrent longing for sexual adventure. What would motivate the males to accept such a trying bargain?

The zookeeper is not surprised that males wind up monogamous. The hand that designed the varieties of life in his zoo consistently shows exacting care for efficiency and symmetry. It would not have rigged a situation as counter-productive as a female who needs monogamous loyalty to produce the next generation and a male who flees it. Males must inevitably have a need for monogamy as well, although their motivation is not obvious.

The Martian zookeeper has developed some theories about why human males make this bargain. First, at the root what feels like a sex urge is actually a reproductive urge. It will do the male no good to impregnate many women if these women are barely able to raise healthy children unaided. The children must survive and be strong enough to carry his genes forward one more generation for reproduction to have truly taken place.

Secondly, how can he know that the child his mate is raising does in fact carry his own genes, and not some other male’s? Ultimately, he can only trust her word on this. In order to persuade her to mate only with him, he must offer her inducements: shelter, provisions, protection and, perhaps most difficult, his own fidelity in pledge. As he watches the mother nurse their child, he sees his only link to the chain of human life. Without his connection to the two of them, he would free-fall into oblivion.

Is biology destiny? No; we are not prisoners of these roles, and our ingenuity can offer many ways to redesign them. But biology is orderly. It has its own internal logic, and when we tamper with one element of it we must expect another element to fall out of place. The superwoman single-mom with a hot career and a hot date is famously exhausted on her treadmill. This should not be surprising. Disrupt biology’s rules and you will find yourself doing things a less-efficient way.***

The other thing the Martian zookeeper notes is the heightened sense of loneliness humans display. They carry a burden of self-awareness that other mammals appear to evade, with associated fears of abandonment, rejection, and meaninglessness. They need more complex things from each other than goats do. Even in old age he sees them in pairs, when the impetus of child-rearing is decades past. Gliding over earth’s atmosphere in his shiny saucer he observes elderly couples on Florida sidewalks wearing identical clothing. What’s that all about?

The Martian is recognizing the profound human need for connectedness, and pregnancy is the icon of human intimacy. The connection an unborn child experiences with her mother is the first any human has of closeness to another person. Because it predates language and self-awareness it is the more profound and ineradicable, though we may be largely unaware of this pull.

Life outside the womb is lonely. We look all our lives for an experience of similar intimacy and safety even though many, as the saying goes, look in all the wrong places. When pregnancy begins, a woman is plunged into an experience of intimacy more profound than any of her adult life; she is knit, literally, to another human, one half-made of her own self. In the same blow she is linked to the child’s father, whose half-life lives on as well within her body. Yet this being formed of two halves is more than their sum, a radical third never before seen on earth. She shoots from her parents’ bodies like an arrow from a bow, carrying their immortality into the future, beyond the reach of their crumbling arms.

Pregnancy is about connectedness. It spins the wheel tighter, and centrifugal force draws the players together, more aware than ever of their mutual dependence. When a pair-bond is healthy, pregnancy makes it stronger still.

But today, unfortunately, many couples begin a sexual relationship without having that strong foundation of interdependence. When pregnancy occurs in such relationships, multiple problems arise: broken trust, fear, loneliness, abandonment.

We are told that the solution is contraception. The Martian zookeeper is perplexed to observe that this seemingly-logical idea doesn’t work in practice. Even though these humans “don’t want” to have unplanned pregnancies, even though contraception is cheap, available, and more effective than nothing, humans often choose not to use it. It looks to him as if sex is another one of those things that is more complicated for humans than it is for other creatures.

Unreckoned with in the contraceptive strategy—indeed, nearly unrecognized in forty years of sexual revolution—is the distinctive character of women’s sexuality. Here are a couple of quotes. The feminist poet Adrienne Rich wrote, “The so-called sexual revolution of the sixties [was] briefly believed to be congruent with the liberation of women…It did not mean that we were free to discover our own sexuality, but rather that we were expected to behave according to male notions of sexuality.”

And Germaine Greer wrote, “Women’s desire for affection and closeness usually has to be translated, more or less unconsciously, into desire for sex.” As the old cliche has it, girls give sex in order to get love; boys give love in order to get sex. When the sexual revolution flooded the market with “free sex,” its trading equivalency in square units of love was radically depreciated.

Women are getting less and less durable love in return for sex, and sooner or later they’ll figure out that it’s a bad bargain. Already we see an unexpected sign among young people, that despite being confronted with every possible variety of sex at the earliest possible ages, the rate of teen virginity is rising. It may be that what our sex-saturated culture has succeeded in conveying is that sex is intense and intimidating, and some kids would rather wait.

There is some evidence for this. In 2002 the Centers for Disease Control found that the vast majority of adolescents are still virgins at the age of 15, and reported that this majority has been increasing since 1995. And a Dec 2003 survey by the National Campaign to Prevent Teen Pregnancy showed that, among teens who have had sex, 67% said they wish they had waited. And 85% said that sex should occur only in the context of a long-term committed relationship.

What’s a long-term committed relationship? Traditionally, it’s one in which you make a commitment, in public, that you intend to stay together long term. It’s called marriage.

The institution of marriage is not in good repair in our current culture. The divorce rate lingers around 50% (although things are not quite as bad as they seem , because that figure includes many people who have had more than one divorce. Thus over 50% of marriages do last a lifetime.)

So marriage can be celebrated for its multiple benefits: it takes into account both the woman’s need for emotional security, and the indications that healthy child-rearing goes best with two parents. Perhaps those needs are the reason that humans are among the very small percentage of mammals – approximately 3% — who mate for life.

But not everyone cheers this concept of marriage—the mated pair with offspring, the “nuclear family.” The way I always used to hear this phrased is “Ozzie and Harriet is a myth.” (Which sounds oddly naïve. “Mr. Ed” was a myth, too.) This viewpoint would insist that marriage can’t be the answer; it disappoints, is imperfect, demands annoying sacrifices, and limits one’s range of sexual adventure.

But the nuclear family is not a wacky new untested idea, likely to damage participants virtually every time. There are centuries of evidence showing how the concept works in practice: pretty good, usually resulting in the survival and success of a new generation, which is humankind’s first responsibility. Bonuses of companionship, romantic love, pleasure and joy often appear as well.

In comparison, an ethic of sexual freedom, where one in four pregnancies ends in abortion and the numbers of children in single-parent homes keeps rising, is going to fail that goal like clockwork. Indicators for sexually transmitted disease, divorce, abandonment, impoverishment of women and children, unwed motherhood, and abortion are at record levels. The heartbreak index is at an all-time high. Despite all this pursuing of happiness, Americans appear to be markedly more unhappy. The flip side of freedom is loneliness.

It is the right-hand side of the cultural spectrum that has historically been more enthusiastic about marriage, while the left has doubted its feasibility. This is somewhat ironic, because, as we saw above, life-long marriage is what best suits women’s desire for security in a sexual relationship. (A friend once told me, “Why did feminism arise on the left? Because it’s men on the left who are hardest on women.”) The pattern over 40 years has been for the left to expect women “to behave according to male notions of sexuality,” while the right upholds woman-friendly notions of chastity, fidelity, life-long marriage, and so forth.

Every few years a study comes out showing that it is women who are both devoutly religious and married who report the highest levels of sexual satisfaction. Everyone is always amazed by this. Maybe it shouldn’t be so hard to figure out.


I once attended a forum on the state of the family, sponsored by a progressive think tank. It presented the daring idea that whenever possible children are better off with two parents. Some impressive speakers, such as T. Berry Brazelton and Barbara Whitehead, argued eloquently that children need intact families.

I sat near a woman who carried a journalist’s notepad and who was not having fun. She passed the morning scowling at the floor, tapping her pencil, tapping her foot, and emitting derisive snorts. When others applauded, she hugged her legal pad to her chest. I guessed that her own life had not followed the pattern being promoted, and so she was feeling uncomfortable.

When the question period began, she raised her hand. She confessed herself “nervous” at the promotion of two-parent families, and informed the crowd that “Ozzie and Harriet is a myth.”

The story doesn’t end there, though. I expect that when she left the conference she wrote a news story about it. How do you think it read? What assumptions did readers absorb?

People often plead for stable marriages on the basis that they benefit children, but children are not the ones we need to convince. Kids are instinctively in favor of the nuclear family. The harder task is convincing grownups who feel compelled to defend their different choices. The leaders in media, education, and government are not likely to promote values they do not meet in their own lives.

In these circumstances, it is hard to gain broad public support of any moral conviction. For example, the idea that teens should be taught to abstain from sex before marriage is attacked, not by teens, but by adults. They protest that expecting abstinence is unrealistic, and it may be they feel it is unrealistic for themselves. They could also be feeling something like the sting of personal insult. A public-school teacher told me that, when she taught her middle-schoolers the reasons to abstain from sex outside marriage, she received angry calls from parents, saying, “Don’t teach my kids to judge how I live!”

We don’t want to be starry-eyed about marriage; we don’t want to suggest that it is always “happier ever after.” There’s a saying that “the good is the enemy of the best,” and expectations that are *too* high can be as damaging to marriage as those that are too low. Children of divorce, particularly, may have an exaggerated idea of how perfect marriage is meant to be, and delay marrying decade after decade for fear that they haven’t found perfection yet. If they were told, with the best intentions, “Mommy and Daddy still love each other, but sometimes this just happens and people have to get divorced,” the child may view divorce as being an uncontrollable force, like a hurricane, that can descend on even the happiest families. They haven’t had a chance to see how a real healthy marriage can look. They might not know that it won’t look perfect.

The author Tolstoy wrote that “happy families are all alike,” and maybe they are alike in not expecting to be happy all the time. Perhaps they expect that problems and disappointments are going to come, and expect to take them in stride. In real marriage—not the TV-show myth—the dishes get dirty, the wife gets plump, the husband gets bald, and everyone gets grumpy at least occasionally. In the course of a lifetime together, everyone will need forgiveness, and happy families learn that giving it is the best way to be sure to receive it in return.

Why put up with these annoyances? For one thing, it is far worse to be alone. The world is too big and we are too small to make it through without being trampled. The bravado of individualism is false; we can never be free enough to be all-powerful, but we can be free enough to be lost. We warm our hands together at the night fire. Behind the other’s back we see, behind our own back we know, the dark wilderness broods.

“It is not good for man to be alone,” but it is also positively good to be together. The light you loved in your lover’s eyes at the beginning grows more compellingly beautiful through the years. You meet those eyes in worship, in passion, in anger, in tears, over the baby’s bassinet, over your father’s casket. There is no substitute for the years, the life-time work, of looking into those eyes. Gradually, you see yourself there; gradually, you become one.

Contrary to popular belief, the Church is not anti-sex. In speaking of the union of the Church with Christ, St. John Chrysostom draws a frank parallel to marital union; the sexual bonding of husband and wife, he says, is like the uniting of fragrance and ointment in the making of perfume. He rebukes those who were shocked at his words: “You call my words immodest, because I speak of the nature of marriage, which is honorable…By calling my words immodest you condemn God, who is the author of marriage.” Chrysostom affirms St. Paul’s image of the Church as the Bride of Christ: “Shall I also tell you how marriage is a mystery of the Church?,” he writes. “The Church was made from the side of Christ, and He united Himself to her in a spiritual intercourse.”

The secular world likes to think that religion is just a way of sublimating feelings about sex. But I think that the truth is something like the opposite: sex is given to teach us something about religion, about faith and union with God. How could human beings understand what it’s like to become one with God. If two became one, wouldn’t their individuality annihilated? God designed it so humans could have an experience that would be universal, common, and enjoyable. He said, in essence, “Here. This is what it’s like. This is where you’re going.” That’s not the only earthly experience that helps us understand theological principles, of course. Eating ordinary food helps us to understand how we become one with Christ in the Eucharist. Parenting teaches us what God the Father’s love for us is like. Sex, eating, parenting, are all good things in themselves, given and blessed by God. But they are also handy as object lessons, able to give us ready, simple, intimate analogies for what heavenly reality will be like. In light of this, I think heaven is going to be not so bad.

But this is not the way the secular world views sex. Advertisements and entertainment are always telling us that what we want most is to wake up next to someone sexy tomorrow morning. But in the quiet of our hearts we know: we want to wake up next to someone kind, fifty years from tomorrow morning.


We’ve made a good case for keeping sexual activity within the bounds of life-long commitment, so far as women and children are concerned. Where the ties of marriage bind a couple securely together, babies are more likely to survive and women more likely to feel safe and loved. But we haven’t talked yet about the man, the father of the child. What’s in it for him? Don’t men’s desires run to sexual adventuring, spurning hearth and home? Why would he agree to such an obligation?

This question came up during a business meeting over dinner at a restaurant, years ago. I was there with three men, all leaders in pro-life and pro-family organizations, and we were talking about a magazine article I was going to write. I asked them about the male side of the relationship puzzle, and all three tried to convince me that men are untrustworthy and incorrigible. Men are shallow, self-centered, and interested only in the next exploit, they said. They would inevitably use women and dump them without a backward glance. “Men just want to do it and run,” one of the guys stated bluntly.

I looked at the tired faces of these three men, winding up another long workday. In three suburban homes, these men’s wives are tucking in the cumulative nine children and ending busy workdays of their own. Those tenderly-loved women had been able to spend that day at home because their husbands were still at work, wearing ties at a meeting at 9:00 PM.

It made me think about sheep in wolves’ clothing. I asked them, If men are all such barely-restrained fiends, why are you going home tonight? Why aren’t you fulfilling the stereotype and running off to an affair?

They registered surprise. Well, because the risks are too high and the benefits too low, they said. Because they sincerely delight in their homes and children. Because being protectors and providers is a role that makes them feel worthy. But most of all, because they love their wives.


The Martian ponders the white-haired man on the sidewalk. He is baking in the Florida sun, waiting outside the craft shop while his wife gathers materials to make another ceramic doll. His lime-green polo shirt and white slacks match her own.

His children are grown, his youth is gone, twenty thousand days and night of marriage have flown past. His days of power, of protecting and providing, have slipped away. He waits quietly in the sun, a little drowsy. There is no reason on earth for him to be there but one.

Frederica Matthewes-Green

About Frederica Matthewes-Green

Frederica Mathewes-Green is a wide-ranging author who has published 10 books and 800 essays, in such diverse publications as the Washington Post, Christianity Today, Smithsonian, and the Wall Street Journal. She has been a regular commentator for National Public Radio (NPR), a columnist for the Religion News Service, Beliefnet.com, and Christianity Today, and a podcaster for Ancient Faith Radio. (She was also a consultant for Veggie Tales.) She has published 10 books, and has appeared as a speaker over 600 times, at places like Yale, Harvard, Princeton, Wellesley, Cornell, Calvin, Baylor, and Westmont, and received a Doctor of Letters (honorary) from King University. She has been interviewed over 700 times, on venues like PrimeTime Live, the 700 Club, NPR, PBS, Time, Newsweek, and the New York Times. She lives with her husband, the Rev. Gregory Mathewes-Green, in Johnson City, TN. Their three children are grown and married, and they have fourteen grandchildren.

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