Commentary Magazine

Sex and the Marriage Market

Everyone knows that this country has suffered a remarkable rise in the number of single-parent, female-headed families, and that things were not always this way. Everyone also knows, and research confirms, that most such families are particularly bad for the children in them, who grow up without fathers, without safety, without a decent life or reasonable prospects for the future. Although the most recent census data suggest a halt or even a slight decline in the steady increase of such families, the fact remains that a large proportion of American children are now growing up and will continue to grow up in fatherless homes.

There are many explanations for this powerful change in our society, which first became noticeable in the late 1950′s and early 1960′s and by the 1990′s seemed unstoppable. But one explanation that is often overlooked takes us into a complex and fascinating area of human behavior, raising questions of both biology and culture that are not easy to sort out. It has to do with the number of men who are available to be married in the first place. We sometimes forget what can happen in a society where either there are many more marriageable men than women or—as has been the case in the United States for quite a number of decades now—there are many more marriageable women than men.

Let me begin with the former scenario: imagine a society in which the number of men in their early twenties is vastly greater than the number of women of the same age. Because there are too few women to marry all men, the competition among men for women will become stronger. To find a wife or a sexual partner, men will have to work harder and promise more. This competition will raise the bargaining power of women, who, within the limits set down by custom and biology, will be able to demand more from their prospective mates.

Consider one such woman, Joan. If a man wishes only to have sex with her, she can, if she wishes, easily reject him for another man who is willing to marry her. If one suitor is less handsome, less intelligent, or less likely to be financially successful than another, Joan can choose the rival. And if one does not seem prepared to support a child or children, Joan can pass him over in favor of another who is committed to matrimony and fatherhood.

Of course, any given Joan might be different: she might shun the market altogether, she might marry her high-school sweetheart or a man she just met at the office, or she might not marry at all. But for women in the aggregate, the relative supply of available men and women will powerfully affect their prospects in the marriage market. Other things being equal, marriage will be more likely when men of the relevant age outnumber women of that age.

Now for the second scenario: imagine a society in which there are fewer marriageable men than women. What are Joan’s prospects then? If there are not enough sexual or marital partners available, she may have to accept what a man offers. It may be a one-night stand, or a few dates, or living together. It may even be marriage. But if the marriage does not work out, Joan will not find a lot of unmarried men to choose from on the next round. And when it comes to children, a man may have so many other sexual opportunities that he cannot be counted on either to marry or to become an effective father. With men thus able to drive a hard bargain for their sexual favors, Joan may be more likely to stay unmarried, or even turn away from marriage altogether in favor of a career. If she does marry, she may have to settle for a man who is not her equal or her superior in financial or educational resources, and as a result of marrying down she may impair her ability to care well for her children.

In brief, when there are many more women than men in the marriageable age range, women will suffer in their efforts to find husbands. Many more of them will have lives like those depicted in the HBO series Sex and the City.



The number of men per hundred women in a society is called the sex ratio. When there are more men than women, we have a high sex ratio; when there are fewer men than women, a low sex ratio. Societies differ in their sex ratios, but in most societies unaffected by disturbances, the ratio will be a bit over 100, since as a rule more male than female children are born.

But disturbances do occur in history, and thus the ratio within a society can change radically over time, becoming vastly higher or lower than 100. A war, for instance, will result in the death of many men: in Great Britain and many other European nations between 1911 and 1926, the sex ratio dropped dramatically as a result of the carnage of World War I. Emigration usually involves the movement of more men than women: when men moved out of small English towns in the 17th and early 18th centuries to find jobs elsewhere in the country or abroad, many local women were destined to become spinsters. Prisons are disproportionately filled with male convicts, and a high crime rate can take a lot of men off the streets. Infant mortality affects more boys than girls. Men, especially unmarried men, are more likely than women to die from murders, auto accidents, alcoholism, drug abuse, and many common illnesses.

All of these factors produce a lower sex ratio—that is, an oversupply of women.

Some societies have developed a way to deal with this oversupply: allow each man to have more than one wife. This practice, called polygyny, has been widespread in the past, especially in cultures where men were regularly engaged in war, raiding, and dangerous occupations, and today still occurs; among Muslims, it is authorized (up to a limit of four wives) by the Qur’an. And it is not hard to imagine why polygyny might be popular: having many wives gives a man a taste of sexual variety, a chance to ensure for himself a large number of progeny, and a reputation for status and power. But none of this is relevant to our society, which like every other Western one is monogamous and does not allow polygyny; and so the problem created for the marriage market by a low sex ratio can remain acute.

As for the opposite situation, an undersupply of women, that can occur when many die in childbirth. It can also occur when young girls are disproportionately made the objects of infanticide or child neglect, as has been true in several ancient societies, including Athens, and continues to be true in modern China. And it can occur in a country or region newly inhabited by immigrants: the American colonies were at first settled by more men than women, there were more men than women imported to this country as slaves, the frontier territories were heavily masculine, and the California gold-mining camps were overwhelmingly made up of men.

If in some places men have been able to adjust to an oversupply of women by taking more than one wife, why cannot women handle an excess number of men by taking several husbands? But no: with a few trivial exceptions, this practice—polyandry—is never found among humans. The striking difference between the number of polygynous and the number of polyandrous societies in history suggests that something important, something involving both culture and biology, dictates marriage patterns.

I shall discuss this below. But first let us revert to the connection between sex ratios and two things: how likely it is that a child will be born out of wedlock, and how likely it is that a child will be raised in a female-headed family.



The most ambitious and influential study of these matters is a 1983 book entitled Too Many Women? by Marcia Guttentag and Paul F. Secord. Their argument is this: when there is a high sex ratio—that is, many more men available than women—marriage will be commonplace and cohabitation will be rare, women will play more traditional roles, and children will be raised in two-parent families. When there is a low sex ratio—that is, many more women available than men—marriages will be less common and more fragile, cohabitation will become more general, divorce will be more frequent, and children will be more likely to be raised in one-parent families, with that one parent being the mother.

The social curve traced by the United States moved historically from the former condition to the latter. From 1790 to about 1910, the United States had a relatively high sex ratio—around 104 or 105. After World War I it fell, and by 1940 it was about 100. It continued to drop in the 1950′s and 1960′s until in 1970 there were 95 men to every 100 women. But, as Guttentag and Secord point out, it was actually much lower than that.

To understand why, it is important to focus not on the total pool of men and women but on a particular slice: namely, unmarried people who are at a marriageable age and of the same race. (Even though the number of interracial unions has grown in recent years, the vast majority of marriages continue to be between persons of the same race.) Men and women tend to marry when they are in their twenties, with a woman usually marrying a man who is two or three years older than she.

If we compare the number of unmarried white men between the ages of twenty-three and twenty-seven with the number of unmarried white women between the ages of twenty and twenty-four, we find that the sex ratio in America in 1970 was not 95 but only 67. Moreover, that gap, or something like it, persisted as the women got older because there was no increase—and almost surely there was a decrease—in the number of unmarried men at the right age for them. So the “availability ratio” shrank still further.

In addition to age and race, education also matters. If women want to marry up, as most seem to do, they must find a man who has attained at least their level of education. For white women who have gone to college, the marriage market deteriorates rapidly after age twenty-five. By the time they reach thirty, there are only half as many unmarried men of the right age and education available for marriage.

Today young women are urged not to marry early but to get an education and start a career. This may or may not be good career guidance, but if the goal is marriage, it is bad advice. As one study shows, in 1980 unmarried female college graduates between the ages of twenty-five and twenty-nine faced five female competitors for every comparable man. Not very good odds—and they get worse depending on where you live. Though San Diego has a lot of men, New York City has a shortage.



Matters are much worse for African-Americans. They have had a lower sex ratio than whites for over a century; by 1970, there were almost two young black women for every young black man, and the ratio was especially low in big cities. Young black men are scarce because they are in prison or overseas in the armed forces, and because black men die at a higher rate than black women from disease, alcoholism, drug abuse, auto accidents, homicide, and suicide.

Of course, we know that the census does not count blacks accurately, and the undercount is greater for black men than for black women, a fact that could make the ratio look lower than it really is. But the black men who tend to be uncounted are probably not likely to appear especially attractive to black women as spouses—they have no real address, or may be in trouble with the law—and so for all practical purposes the sex ratio may be as low as the census count suggests. One study that made adjustments for an undercount found little change in the proportion of available mates.

The problem of sex ratios among blacks has become the focus of research by many scholars. Daniel Lichter, for example, has found that if African-American women had access to more potential marriage partners, more would get married. This would certainly help the marriage problem for African-American women—and it suggests an additional reason for trying to save young black males from premature death, especially by murder—but it would not solve it. Because the legacy of slavery and its immediate aftermath discouraged marriage, black women are still less likely to marry than white ones, even allowing for the low sex ratio.

Similarly, illegitimacy and single-parent families are much more common among blacks than whites, although in the 1990′s whites were catching up fast. Using 1970 numbers, Guttentag and Secord found that the correlation between the sex ratios of black Americans and the proportion of black births that were illegitimate was -0.87. Making the same calculation for the white sex ratio and the white illegitimacy rate, they got a result of -0.27. For both racial groups, in short, the sex ratio made a difference, but for blacks the impact was more than three times as great.

A child born out of wedlock might nevertheless be raised in a household with a husband and father if its parents married, or at least lived regularly together, after its birth. But Guttentag and Secord found that where black women outnumber black men, children tend to lack fathers. They reached their conclusion using 1970 figures and by comparing overall black sex ratios with the percentage of female-headed black families. I made a similar calculation based on 1990 census data and limiting the analysis to the total sex ratio among people who are unmarried and of marriageable age.1

I used two different measures: the number of illegitimate births per thousand women aged fifteen through twenty-four (call this the “illegitimacy rate”) and the proportion of all births to women aged fifteen through twenty-four that were illegitimate (call this the “illegitimacy ratio”).2 The lower the proportion of men to women in a state, the more likely it was for there to be more out-of-wedlock births by either measure, rate or ratio. This link was strongest for African-Americans. Much the same results have been obtained by other scholars who have looked at the sex ratio in metropolitan areas.

All of these results bring to mind the well-known argument of William Julius Wilson that the central family problem of African-Americans is the shortage of employed black men of marriageable age. It is indeed true that the availability of such men fell sharply after 1950 in comparison with the number of women of the same race and age. But joblessness cannot be the whole story. High levels of illegitimate births and single-parent families are associated with a shortage of unmarried black men whether employed or not—and, as Christopher Jencks has pointed out, there has been as sharp a decline in marriage among employed black males as among unemployed ones. There is also the counterexample of Latino male immigrants, who also live in central cities, have higher unemployment rates than black men, often do not speak English very well, and may be here illegally—but who are much less likely to sire children out of wedlock or to abandon children whom they have fathered. Once again, something else is going on. To find out what requires a more general discussion of men and women.



When there are a lot of men and many fewer women, the women have an advantage, but to what end? When there are a lot of women and many fewer men, the women are at a disadvantage, but what is the nature of that disadvantage?

In the first situation—more men than women—women are in principle free to do whatever they want in order to advance their sexual interests.

Having a great deal of bargaining power, they could decide to ignore the bonds of marriage and just have sex with as many men as they like. They might even create male brothels run by female pimps and start pornography shops that catered exclusively to women. They could require men to raise their babies while the women played cards, watched (women’s) soccer games on television, and went out to bars to drink with other women.

In the second situation, where there are not many men and women have to work hard to find sexual partners, a woman could in theory decide to become a prostitute or, conversely, enter a nunnery or become an unmarried member of a profession. If she wanted to have a child, she might live unmarried with several men who would in effect be trying her out, or settle for having a baby without being married. In short, she could either go along with whatever men wanted or renounce men and motherhood and view marriage as a useless, outmoded invention.

These are the alternatives in theory; reality is quite different. No matter how few women may exist in a society, we do not hear of many of them patronizing pornography shops or requiring men to abandon their careers, be virgins before they are married, or stay home and raise the babies while their wives go out drinking. Similarly, no matter how few men exist in a society, relatively few women renounce marriage altogether, or become more promiscuous than men, or usually prefer cohabitation to marriage.

Guttentag and Secord offer two explanations for these facts, culture and biology, but they develop only the first. Their cultural explanation, which leans heavily on anthropology, is that in every society, men dominate. They have “structural power” that is based on their control over the economy and their overrepresentation in government and the legal system.

What this means for the marriage market is that when there are many men competing for relatively few women, women can indeed become selective—but only up to a point. Most will still choose to be wives and live within the definition of wifeliness that conforms to contemporary male expectations. Even as men take over more child-care duties and household chores, women will spend more time at home with their children than their husbands, and will still do most of the chores. If they enter the labor force, they will usually earn somewhat less than males of the same age and education because, thanks largely to motherhood, they will have less seniority.

I think Guttentag and Secord are right to argue that culture shapes women’s (and men’s) choices, and that every culture in the world encourages or requires men to be in the front rank. But cultures can change, and cultures differ. Thus, according to one study, the influence of the sex ratio on women’s marriage and fertility rates is much less pronounced in nations where a high number of women are in the paid work force than in less developed countries where women have fewer paid jobs. Economic advancement gives women more choices.

There are other obvious examples of how different cultures have different effects on behavior. Very high sex ratios—lots of men, few women—characterized old California gold-mining towns, Southern colonies in the 17th and 18th centuries, and the communities of Chinese laborers brought to this country to build the railroads. But there were important differences between the first two and the third.

Southern and gold-rush Americans placed decent women on pedestals, defending their honor and attacking any who would detract from it. (Side by side with this, of course, was a rowdy male preoccupation with prostitutes and an attachment to alcohol, violence, and an often sordid way of life.) In Yellowstone City, the law once imposed a death sentence on anyone insulting a respectable woman. Some cowboys were even afraid to talk to decent women for fear of getting into trouble. As late as the 1910′s, the historian David Courtwright reports, Wyoming ranch hands would call out “church time!” when a married woman approached, and then lapse into an awkwardly respectful silence. Frontier women often held good jobs at relatively high pay and attended school more regularly than did their Eastern counterparts.

These circumstances may help us understand an otherwise puzzling fact: though the political movement for women’s suffrage was based in the East, the eleven states that had, by the end of 1914, granted women the vote were all in the West, with wild, boisterous Wyoming leading the pack. Sophisticated Easterners argued for female suffrage, but primitive Westerners enacted it. The reason, in most cases, was the belief that if women could vote they would help civilize the territory. As the historian Alan Grimes put it, “men conquered the wilderness, women made it habitable.”

The Chinese laborers who came to the West in the 19th century also had a high sex ratio—in 1890, there were 27 Chinese men for every Chinese woman—but they managed to put most of the few women who arrived into servitude as prostitutes, while others became the brides of rich men who kept them in a state of nearly complete isolation. Almost none went to school and, other than as prostitutes, few worked.

Just as culture explains why Caucasian women were the objects of deference, culture explains why, at the very same time, Chinese women were treated as property. Caucasian frontier life was open, loose, and only lightly regulated from above, thus enhancing female bargaining power. By contrast, early Chinese social life in this country was dominated by the Triad, the secret societies that celebrated fraternity, encouraged criminality, and helped keep women under centralized control.

Culture, enforced from the outside by lash and gun, also helps explain why African-American marriages were less common during slavery. Usually more men than women were kidnapped and imported, producing a very high sex ratio. But male slaves had no opportunity to define, as frontiersmen did, the difference between respectable and not-so-respectable women. Given the limits imposed by their condition, African-American males took advantage of what opportunities they could and had many sexual liaisons with relatively few marriages.



But these cultural considerations are not the whole story. Biology sets important limits on how far culture can change things. Nowhere do we find any society, whatever its sex ratio, in which women dominate the government, are the principal consumers of pornography and prostitution, or make men do most of the childrearing. Even in the most egalitarian societies, like Sweden, single-parent homes are headed, in the great majority of cases, by women.

Culture and biology—nature and nurture—interact in powerful ways, especially with respect to those social arrangements that are important and durable. Everywhere men commit more violent crimes than women, are more likely to get into auto accidents and street fights, and are more likely to make violent threats. This is not because they are driven by a “violence gene,” but probably because their evolutionary past has led them to compete vigorously for social rewards, including access to the most desirable women. And if they obtain those rewards, they will struggle hard to maintain them. Men are physically stronger than women, but what is just as important is that they are more willing to use that strength to get what they value.

Based on studies done in many different cultures, David Buss has shown that while both men and women chiefly value intelligence and kindness in prospective mates, men also greatly value physical attractiveness while women greatly value status and earning power. This was evident in American studies done in 1939 and persists in studies done in the 1980′s, long after the sexual revolution had occurred. On average, both men and women want a pleasant mate, but to this preference men add beauty while women add financial capacity.

Much of what we observe about human behavior today follows from these simple requirements. Men want to sire progeny, and so they prefer young and attractive wives. Women want to manage child care, and so they choose husbands who seem to have good economic prospects. Men want to guarantee that the children they support will be theirs, and so they become enraged at the sexual infidelity of their wives. Women want to keep their husbands’ necessary child support, and so they worry about a lack of emotional commitment. Men, if they can afford it, are tempted to acquire more wives, and, in societies where polygyny is out of the question, may do so illegally or serially—first a wife who is the children’s mother and, then, when the wife ages, either a mistress or a new, younger wife to provide sexual excitement and social status. Women are keenly aware of this possibility, which is probably another reason why they worry more about emotional commitment than about sexual regularity. And though an economically successful woman could abandon her first husband for a new boy toy, that happens much less frequently than a man’s abandoning his first wife for a trophy version.



In many primitive societies, male aggressiveness is physical and even brutal, but though modernity has found important alternatives to war and pillage it has only sublimated the motives that produce aggression into a contest for status, wealth, and political power. A great achievement of modern times has been not to weaken male aggressiveness but to convert it from the physical and military realms to the economic and political ones. Samuel Johnson once remarked that every meeting and every conversation is a contest in which the man of superior parts is the victor. That aggressiveness helps explain why men are more likely than women to be focused on occupational achievement and to value it as much as or more than they value family attachments, to work longer hours and to take greater risks.

Culture plays a part here, and culture, as I have already observed, can change. American women now make up a large proportion—sometimes the majority—of people studying to become lawyers, physicians, architects, and veterinarians, and they have entered all kinds of civilian and military occupations. This transformation has helped women, moderated male aggressiveness, and had mixed effects on marriage—reducing the wife’s financial dependence on a man while at the same time making it easier for child-rearing to be given to outside parties of uncertain talents.

But biology, though it is not destiny, will—once again—place limits on how far this cultural change can proceed. Most women want children. To give birth to and nurse infants, they will drop out of the seniority rat-race, thereby yielding space to their male rivals. Some will discover that being a mother is more rewarding than being an investment banker. And even if they do not give ground in order to acquire children, male aggressiveness, now channeled into bureaucratic in-fighting and political struggles, will give men an edge—not a decisive advantage, but an edge—in the struggle for success.

But there is a simpler illustration of the role played by biology in the sex ratio’s differential impact on men and women. Forget tastes in beauty or differences in physical strength, important as those are. The central fact of family life is that when a father and a mother do not live together, for whatever reason, it is the woman who in the vast majority of cases winds up with the children. The sacrifices women make for their children are much greater than the ones men make, and these commitments explain why, whenever a choice must be made between sex or careerism on the one hand and parenthood on the other, women will choose the latter much more often than will men.

When the sex ratio changes, the way men and women pursue their sexual interests must also change. The magnitude of that change will vary because of culture and under the influence of economic development, but neither culture nor the economy will prevent change from occurring at all. When there is a shortage of young females, most men will devote themselves to finding and marrying a woman because, unless they can offer a serious commitment, any desirable woman will turn to a rival who will. Conversely, when there is a shortage of men, many women will settle for less than what they had hoped for by becoming spinsters, accepting casual offers of sex from men who offer no marital prospects, or producing babies without being married to their fathers.



This brings us back to where we began: the high number of single-parent, female-headed families in our country. I have argued that this phenomenon is related to, among other things, the low sex ratio that has been our lot in the last decades. There are no signs of a significant change in that condition. But, as is evident from the different effects the ratio has had on black and white Americans, there is more to life than the sex ratio, important as it is. After all, there have been low sex ratios in the past—as recently as the 1940′s—that have not produced anything like the high rate of mother-only families that we observe today.

The 60′s is the time when many of us suppose that (depending on our point of view) things in general got a whole lot worse or a whole lot better in this country. But there were two major shifts that preceded the 60′s by many decades. The first of them, slavery, affected American blacks in particular. Yanked from their homelands, traded on blocks, and subjected to a master’s sense of justice that was unconstrained by law, black men and women were told that they could not have a wedding, own property on which to live, or (on small plantations where men were often sent away for jobs in other places) even live together for very long.

The second shift was, in shorthand, the advent of modern individualism. This told free people that marriage, once a sacrament and then an obligation enforced by law and village opinion, was now an arrangement to be agreed to only as it suited the individual preferences of a man and a woman. The effects of this were palpable enough on people who had had a long and universal experience with marriage as the ordinary basis of male-female relations. Under the wide extension of human freedom in which they now lived, many began to think of social convention and public opinion as unnecessary and burdensome restrictions. But the effects were even more immediate and more pronounced in the case of former slaves who became sharecroppers or moved to big cities and found themselves unable to resist the powerful social currents to which these relocations exposed them.

By the second decade of the 20th century, many states had begun to pay money to mothers who were widows or divorcees; by the fourth decade, some began to do so even if the women were not widows or divorcees but the heads of single-parent families. By the seventh decade—the 60′s—these payments began to rise dramatically in number. The rest of the story is well known.

The dramatic increase in single-parent families is an immense social change. I have tried to illuminate one aspect of it that has received less public attention than it deserves, but the phenomenon as a whole is far from reducible to any single or simple cause. Nor is it likely to be affected, let alone undone, by any single or simple policy.



1 Russell Burgos gave me invaluable assistance in this exercise.

2 The rate—the number of illegitimate births per thousand women—can go up just because women are having more babies or go down just because they are having fewer. The ratio tells you what fraction of all births are out of wedlock For a good discussion of these indicators, see Charles Murray, “Does Welfare Bring More Babies?” Public Interest, Spring 1994.


About the Author

James Q. Wilson, a veteran contributor to COMMENTARY, is the Ronald Reagan professor of public policy at Pepperdine University in California.