The Marriage Market - Sex, Romance, And Love

The Moral Animal - Whe We Are The Way We Are: The New Science of Evolutionary Psychology - Robert Wright 1995

The Marriage Market
Sex, Romance, And Love

It is hardly possible to read Mr. M'Lennan's work and not admit that almost all civilised nations still retain some traces of such rude habits as the forcible capture of wives. What ancient nation, as the same author asks, can be named that was originally monogamous?

The Descent of Man (1871)1

Something about the world doesn't seem to make sense. On the one hand, it is run mostly by men. On the other hand, in most parts of it, polygamy is illegal. If men really are the sort of animals described in the two previous chapters, why did they let this happen?

Sometimes this paradox gets explained away as a compromise between the male and female natures. In an old-fashioned, Victorian-style marriage, men get routine subservience in exchange for keeping their wanderlust more or less under control. The wives cook, clean, take orders, and put up with all the unpleasant aspects of a regular male presence. In return, the husbands graciously agree to stick around.

This theoiy, however appealing, is beside the point. Granted, within any monogamous marriage there is compromise. And within any two-man prison cell there is compromise. But that doesn't mean prisons were invented by a compromise among criminals. Compromise {93} between men and women is the way monogamy endures (when it does), but it's no explanation of how monogamy got here.

The first step toward answering the "Why monogamy" question is to understand that, for some monogamous societies on the anthropological record — including many hunter-gatherer cultures — the question isn't all that perplexing. These societies have hovered right around the subsistence level. In such a society, where little is stowed away for a rainy day, a man who stretches his resources between two families may end up with few or no surviving children. And even if he were willing to gamble on a second family, he'd have trouble attracting a second wife. Why should she settle for half of a poor man if she can have all of one? Out of love? But how often will love malfunction so badly? Its very purpose, remember, is to attract her to men who will be good for her progeny. Besides, why should her family — and in preindustrial societies families often shape a bride's "choice" forcefully and pragmatically — tolerate such foolishness?

Roughly the same logic holds if a society is somewhat above the subsistence level but all men are about equally above it. A woman who chooses half a husband over a whole one is still settling for much less in the way of material well-being.

The general principle is that economic equality among men — especially, but not only, if near the subsistence level — tends to short-circuit polygyny. This tendency by itself dispels a good part of the monogamy mystery, for more than half of the known monogamous societies have been classified as "nonstratified" by anthropologists.2 What really demand explanation are the six dozen societies in the history of the world, including the modern industrial nations, that have been monogamous yet economically stratified. These are true freaks of nature.

The paradox of monogamy amid uneven affluence has been stressed especially by Richard Alexander, one of the first biologists to broadly apply the new paradigm to human behavior. When monogamy is found in subsistence-level cultures, Alexander calls it "ecologically imposed." When it appears in more affluent, more stratified cultures, he calls it "socially imposed."3 The question is why society imposed it.

The term socially imposed may offend some people's romantic {94} ideals. It seems to imply that, in the absence of bigamy laws, women would flock toward money, gleefully signing on as second or third wife so long as there was enough of it to go around. Nor is the term flock used lightly here. There is a tendency for polygyny to occur in bird species whose males control territories of sharply differing quality or quantity. Some female birds are quite happy to share a male so long as he has a lot more real estate than any male they could have monopolized.4 Most human females would like to think they are guided by a more ethereal sort of love, and that they have somewhat more pride than a long-billed marsh wren.

And of course they do. Even in polygynous cultures, women are often less than eager to share a man. But, typically, they would rather do that than live in poverty with the undivided attention of a ne'er-do-well. It is easy for well-educated, upper-class women to scoff at the idea that any self-respecting woman would willingly suffer the degradation of polygyny, or to deny that women place great emphasis on a husband's income. But upper-class women seldom even meet a man with a low income, much less face the prospect of marrying one. Their milieu is so economically homogeneous that they don't have to worry about finding a minimally adequate provider; they can refocus their search, and spend their time pondering a prospective mate's taste in music and literature. (And these tastes are themselves cues to a man's socioeconomic status. This is a reminder that the Darwinian evaluation of a mate needn't be consciously Darwinian.)

In favor of Alexander's belief that there's something artificial about highly stratified yet monogamous societies is the fact that polygyny tends to lurk stubbornly beneath their surface. Though being a mistress is even today considered at least mildly scandalous, a number of women seem to prefer that role to the alternative: a greater commitment from a man of lesser means — or, perhaps, a commitment from no man.

Since Alexander began stressing the two kinds of monogamous societies, his distinction has drawn a second, more subtle, kind of support. The anthropologists Steven J. C. Gaulin and James S. Boster have shown that dowry — a transfer of assets from the bride's to the groom's family — is found almost exclusively in societies with {95} socially imposed monogamy. Thirty-seven percent of these stratified nonpolygynous societies have had dowry, whereas 2 percent of all nonstratified nonpolygynous societies have. (For polygynous societies the figure is around 1 percent.)5 Or, to put it another way: although only 7 percent of societies on record have had socially imposed monogamy, they account for 77 percent of societies with a dowry tradition. This suggests that dowry is the product of a market disequilibrium, a blockage of marital commerce; monogamy, by limiting each man to a single wife, makes wealthy men artificially precious commodities, and dowry is the price paid for them. Presumably, if polygyny were legalized, the market would right itself more straightforwardly: males with the most money (and perhaps with the most charm and the ruggedest physiques and whatever else might partly outweigh considerations of wealth) would, rather than fetch large dowries, have multiple wives.


If we adopt this way of looking at things — if we abandon a Western ethnocentric perspective and hypothetically accept the Darwinian view that men (consciously or unconsciously) want as many sex-providing and child-making machines as they can comfortably afford, and women (consciously or unconsciously) want to maximize the resources available to their children — then we may have the key to explaining why monogamy is with us today: whereas a polygynous society is often depicted as something men would love and women would hate, there is really no natural consensus on the matter within either sex. Obviously, women who are married to a poor man and would rather have half of a rich one aren't well served by the institution of monogamy. And, obviously, the poor husband they would gladly desert wouldn't be well served by polygyny.

Nor are these superficially ironic preferences confined to people near the bottom of the income scale. Indeed, in sheerly Darwinian terms, most men are probably better off in a monogamous system and most women worse off. This is an important point, and warrants a brief illustrative detour.

Consider a crude and offensive but analytically useful model of the marital marketplace. One thousand men and one thousand women {96} are ranked in terms of their desirability as mates. Okay, okay: there isn't, in real life, full agreement on such things. But there are clear patterns. Few women would prefer an unemployed and rudderless man to an ambitious and successful one, all other things being even roughly equal; and few men would choose an obese, unattractive, and dull woman over a shapely, beautiful, sharp one. For the sake of intellectual progress, let's simplemindedly collapse these and other aspects of attraction into a single dimension.

Suppose these 2,000 people live in a monogamous society and each woman is engaged to marry the man who shares her ranking. She'd like to marry a higher-ranking man, but they're all taken by competitors who outrank her. The men too would like to marry up, but for the same reason can't. Now, before any of these engaged couples gets married, let's legalize polygyny and magically banish its stigma. And let's suppose that at least one woman who is mildly more desirable than average — a quite attractive but not overly bright woman with a ranking of, say, 400 — dumps her fiance (male #400, a shoe salesman) and agrees to become the second wife of a successful lawyer (male #40). This isn't wildly implausible — forsaking a family income of around $40,000 a year, some of which she would have to earn herself by working part-time at a Pizza Hut, for maybe $100,000 a year and no job requirement (not to mention the fact that male #40 is a better dancer than male #400).6

Even this first trickle of polygynous upward mobility makes most women better off and most men worse off. All 600 women who ranked below the deserter move up one notch to fill the vacuum; they still get a husband all to themselves, and a better husband at that. Meanwhile 599 men wind up with a wife slightly inferior to their former fiancees — and one man now gets no wife at all. Granted: in real life, the women wouldn't move up in lockstep. Very early in the process, you'd find a woman who, pondering the various intangibles of attraction, would stand by her man. But in real life, you'd probably have more than a trickle of upward mobility in the first place. The basic point stands: many, many women, even many women who will choose not to share a husband, have their options expanded when all women are free to share a husband.7 By the same token, many, many men can suffer at the hands of polygyny. {97}

All told, then, institutionalized monogamy, though often viewed as a big victory for egalitarianism and for women, is emphatically not egalitarian in its effects on women. Polygyny would much more evenly distribute the assets of males among them. It is easy — and wise — for beautiful, vivacious wives of charming, athletic corporate titans to dismiss polygyny as a violation of the basic rights of women. But married women living in poverty — or women without a husband or child, and desirous of both — could be excused for wondering just which women's rights are protected by monogamy. The only underprivileged citizens who should favor monogamy are men. It is what gives them access to a supply of women that would otherwise drift up the social scale.

So neither gender, as a whole, belongs on either side of the imaginary bargaining table that yielded the tradition of monogamy. Monogamy is neither a minus for men collectively nor a plus for women collectively; within both sexes, interests naturally collide. More plausibly, the grand, historic compromise was cut between more fortunate and less fortunate men. For them, the institution of monogamy does represent a genuine compromise: the most fortunate men still get the most desirable women, but they have to limit themselves to one apiece. This explanation of monogamy — as a divvying up of sexual property among men — has the virtue of consistency with the fact that opened this chapter: namely, that it is men who usually control sheerly political power, and men who, historically, have cut most of the big political deals.

This is not to say, of course, that men ever sat down and hammered out the one-woman-per-man compromise. The idea, rather, is that polygyny has tended to disappear in response to egalitarian values — not values of equality between the sexes, but of equality among men. And maybe "egalitarian values" is too polite a way of putting it. As political power became distributed more evenly, the hoarding of women by upper-class men simply became untenable. Few things are more anxiety-producing for an elite governing class than gobs of sex-starved and childless men with at least a modicum of political power.

This thesis remains only a thesis.8 But reality at least loosely fits it. Laura Betzig has shown that in preindustrial societies, extreme {98} polygyny often goes hand in hand with extreme political hierarchy, and reaches its zenith under the most despotic regimes. (Among the Zulu, whose king might monopolize more than a hundred women, coughing, spitting, or sneezing at his dining table was punishable by death.) And the allocation of sexual resources by political status has often been fine-grained and explicit. In Inca society, the four political offices from petty chief to chief were allotted ceilings of seven, eight, fifteen, and thirty women, respectively.9 It stands to reason that as political power became more widely disbursed, so did wives. And the ultimate widths are one-man-one-vote and one-man-one-wife. Both characterize most of today's industrialized nations.

Right or wrong, this theory of the origin of modern institutionalized monogamy is an example of what Darwinism has to offer historians. Darwinism does not, of course, explain history as evolution; natural selection doesn't work nearly fast enough to drive ongoing change at the level of culture and politics. But natural selection did shape the minds that do drive cultural and political change. And understanding how it shaped those minds may afford fresh insight into the forces of history. In 1985 the eminent social historian Lawrence Stone published an essay that stressed the epic significance of the early Christian emphasis on the fidelity of husbands and the permanence of marriage. After reviewing a couple of theories as to how this cultural innovation spread, he concluded that the answer "remains obscure."10 Perhaps a Darwinian explanation — that, given human nature, monogamy is a straightforward expression of political equality among men — deserved at least a mention. It may be no accident that Christianity, which served as a vehicle for monogamy politically as well as intellectually, has often pitched its message to poor and powerless men.11


This Darwinian analysis of marriage complicates the choice between monogamy and polygyny. For it shows that the choice isn't between equality and inequality. The choice is between equality among men and equality among women. A tough call.

There are several conceivable reasons to vote for equality among {99} men (that is, monogamy). One is to dodge the wrath of the various feminists who will not be convinced that polygyny liberates downtrodden women. Another is that monogamy is the only system that, theoretically at least, can provide a mate for just about everyone. But the most powerful reason is that leaving lots of men without wives and children is not just inegalitarian; it's dangerous.

The ultimate source of the danger is sexual selection among males. Men have long competed for access to the scarcer sexual resource, women. And the costs of losing the contest are so high (genetic oblivion) that natural selection has inclined them to compete with special ferocity. In all cultures, men wreak more violence, including murder, than women. (Indeed, across the animal kingdom, males are the more belligerent sex, except in those species, such as phalaropes, where male parental investment is so high females can reproduce more often than males.) Even when the violence isn't against a sexual rival, it often boils down to sexual competition. A trivial dustup may escalate until one man kills another to "save face" — to earn the sort of raw respect that, in the ancestral environment, could have raised status and brought sexual rewards.12

Fortunately, male violence can be dampened by circumstance. And one circumstance is a mate. We would expect womanless men to compete with special ferocity, and they do. An unmarried man between twenty-four and thirty-five years of age is about three times as likely to murder another male as is a married man the same age. Some of this difference no doubt reflects the kinds of men that do and don't get married to begin with, but Martin Daly and Margo Wilson have argued cogently that a good part of the difference may lie in "the pacifying effect of marriage."13

Murder isn't the only thing an "unpacified" man is more likely to do. He is also more likely to incur various risks — committing robbery, for example — to gain the resources that may attract women. He is more likely to rape. More diffusely, a high-risk, criminal life often entails the abuse of drugs and alcohol, which may then compound the problem by further diminishing his chances of ever earning enough money to attract women by legitimate means.14

This is perhaps the best argument for monogamous marriage, with its egalitarian effects on men: inequality among males is more {100} socially destructive — in ways that harm women and men — than inequality among women. A polygynous nation, in which large numbers of low-income men remain mateless, is not the kind of country many of us would want to live in.

Unfortunately, this is the sort of country we already live in. The United States is no longer a nation of institutionalized monogamy. It is a nation of serial monogamy. And serial monogamy in some ways amounts to polygyny.15 Johnny Carson, like many wealthy, high-status males, spent his career monopolizing long stretches of the reproductive years of a series of young women. Somewhere out there is a man who wanted a family and a beautiful wife and, if it hadn't been for Johnny Carson, would have married one of these women. And if this man has managed to find another woman, she was similarly snatched from the jaws of some other man. And so on — a domino effect: a scarcity of fertile females trickles down the social scale.

As abstractly theoretical as this sounds, it really can't help but happen. There are only about twenty-five years of fertility per woman. When some men dominate more than twenty-five years' worth of fertility, some man, somewhere, must do with less. And when, on top of all the serial husbands, you add the young men who live with a woman for five years before deciding not to marry her, and then do it again (perhaps finally, at age thirty-five, marrying a twenty-eight-year-old), the net effect could be significant. Whereas in 1960 the fraction of the population age forty or older that had never married was about the same for men and women, by 1990 the fraction was markedly larger for men than for women.16

It is not crazy to think that there are homeless alcoholics and rapists who, had they come of age in a pre-1960s social climate, amid more equally distributed female resources, would have early on found a wife and adopted a lower-risk, less destructive lifestyle. Anyway, you don't have to buy this illustration to buy the point itself: if polygyny would indeed have pernicious effects on society's less fortunate men, and indirectly on the rest of us, then it isn't enough to just oppose legalized polygyny. (Legalized polygyny wasn't a looming political threat last time I checked, anyway.) We have to worry about the de facto polygyny that already exists. We have to ask not {101} whether monogamy can be saved, but whether it can be restored. And we might be enthusiastically joined in this inquiry not only by discontented wifeless men, but by a large number of discontented former wives — especially the ones who had the bad fortune to marry someone less wealthy than Johnny Carson.


This view of marriage is a textbook example of how Darwinism can and can't legitimately enter moral discourse. What it can't do is furnish us with basic moral values. Whether, for example, we want to live in an egalitarian society is a choice for us to make; natural selection's indifference to the suffering of the weak is not something we need emulate. Nor should we care whether murder, robbery, and rape are in some sense "natural." It is for us to decide how abhorrent we find such things and how hard we want to fight them.

But once we've made such choices, once we have moral ideals, Darwinism can help us figure out which social institutions best serve them. In this case, a Darwinian outlook shows the prevailing marital institution, serial monogamy, to be in many ways equivalent to polygyny. As such, this institution is seen to have inegalitarian effects on men, working against the disadvantaged. Darwinism also highlights the costs of this inequality — violence, theft, rape.

In this light, old moral debates assume a new cast. For example, the tendency of political conservatives to monopolize the argument for "family values" starts to look odd. Liberals, concerned about the destitute, and about the "root causes" of crime and poverty, might logically develop a certain fondness for "family values." For a drop in the divorce rate, by making more young women accessible to low-income men, might keep an appreciable number of men from falling into crime, drug addiction, and, sometimes, homelessness. {102}

Of course, given the material opportunities that polygyny (even de facto polygyny) may afford poor women, one can also imagine a liberal argument against monogamy. One can even imagine a liberal feminist argument against monogamy. And, in any event, one can see that a Darwinian feminism will be a more complicated feminism.

Viewed in Darwinian terms, "women" are not a naturally coherent interest group; there is no single sisterhood.17

There is one other kind of fallout from current marital norms that comes into focus through the new paradigm: the toll taken on children. Martin Daly and Margo Wilson have written, "Perhaps the most obvious prediction from a Darwinian view of parental motives is this: Substitute parents will generally tend to care less profoundly for children than natural parents." Thus, "children reared by people other than their natural parents will be more often exploited and otherwise at risk. Parental investment is a precious resource, and selection must favor those parental psyches that do not squander it on nonrelatives."18

To some Darwinians, this expectation might seem so strong as to render its verification a waste of time. But Daly and Wilson took the trouble. What they found surprised even them. In America in 1976, a child living with one or more substitute parents was about one hundred times more likely to be fatally abused than a child living with natural parents. In a Canadian city in the 1980s, a child two years of age or younger was seventy times more likely to be killed by a parent if living with a stepparent and natural parent than if living with two natural parents. Of course, murdered children are a tiny fraction of the children living with stepparents; the divorce and remarriage of a mother is hardly a child's death warrant. But consider the more common problem of nonfatal abuse. Children under ten were, depending on their age and the particular study in question, between three and forty times more likely to suffer parental abuse if living with a stepparent and a natural parent than if living with two natural parents.19

It is fair to infer that many less dramatic, undocumented forms of parental indifference follow this rough pattern. After all, the whole reason natural selection invented paternal love was to bestow benefits on offspring. Though biologists call these benefits "investment," that doesn't mean they're strictly material, wholly sustainable through monthly checks. Fathers give their children all kinds of tutelage and guidance (more, often, than either father or child realizes) and guard them against all kinds of threats. A mother alone simply can't pick up the slack. A stepfather almost surely won't pick up much, if any {103} of it. In Darwinian terms, a young stepchild is an obstacle to fitness, a drain on resources.

There are ways to fool mother nature, to induce parents to love children that aren't theirs. (Hence cuckoldry.) After all, people can't telepathically sense that a child is carrying their genes. Instead, they rely on cues that, in the ancestral environment, would have signified as much. If a woman feeds and cuddles an infant day after day, she may grow to love the child, and so may a man who has been sleeping with her for years. This sort of bonding is what makes adopted children lovable and nannies loving. But both theory and casual observation suggest that, the older a child is when first seen by the substitute parent, the less likely deep attachment is. And a large majority of children who acquire stepfathers are past infancy.

One can imagine arguments among reasonable and humane people over whether a strongly monogamous society is better than a strongly polygynous one. But this much seems less controversial: whenever marital institutions — in either kind of society — are allowed to dissolve, so that divorce and unwed motherhood are rampant, and many children no longer live with both natural parents, there will ensue a massive waste of the most precious evolutionary resource: love. Whatever the relative merits of monogamy and polygyny, what we have now — serial monogamy, de facto polygyny — is, in an important sense, the worst of all worlds.


Obviously, Darwinism won't always simplify moral and political debate. In this case, by stressing the tension between equality among men and among women, it actually complicates the question of which marital institutions best serve our ideals. Still, the tension was always there; at least now it's in the open, and debate can proceed in stronger light. Further, once we have decided, with help from the new paradigm, which institutions best serve our moral ideals, Darwinism can make its second kind of contribution to moral discourse: it can help us figure out what sorts of forces — which moral norms, which social policies — help nourish those institutions. {104}

And here comes another irony in the "family values" debate: conservatives may be surprised to hear that one of the best ways to strengthen monogamous marriage is to more equally distribute income.20 Young single women will feel less inclined to tempt husband A away from wife A if bachelor B has just as much money. And husband A, if he's not drawing flirtatious looks from young women, may feel more content with wife A, and less inclined to notice her wrinkles. This dynamic presumably helps explain why monogamous marriage has often taken root in societies with little economic stratification.

One standard conservative argument against antipoverty policies is their cost: taxes burden the affluent and, by reducing their incentive to work, lower overall economic output. But if one goal of the policy is to bolster monogamy, then making the affluent less affluent is a welcome side effect. Monogamy is threatened not just by poverty in an absolute sense but also by the relative wealth of the wealthy. That reducing this wealth cuts overall economic output may, of course, still be regrettable; but once we add more stable marriages to the benefits of income redistribution, the regret should lose a bit of its sting.

One might imagine that this whole analysis is steadily losing its relevance. After all, as more women enter the workforce, they can better afford to premise their marital decisions on something other than the man's income. But remember: we're dealing with women's deep romantic attractions, not just their conscious calculation, and these feelings were forged in a different environment. To judge by hunter-gatherer societies, males during human evolution controlled most of the material resources. And even in the poorest of these societies, where disparities in male wealth are hard to detect, a father's social status often translates subtly into advantages for offspring, material and otherwise, in ways that a mother's social status doesn't.21 Though a modern woman can of course reflect on her wealth and her independently earned status, and try to gauge marital decisions accordingly, that doesn't mean she can easily override the deep aesthetic impulses that had such value in the ancestral environment. In fact, modern women manifestly do not override them. Evolutionary {105} psychologists have shown that the tendency of women to place greater emphasis than men on a mate's financial prospects persists regardless of the income or expected income of the women in question.22

So long as a society remains economically stratified, the challenge of reconciling lifelong monogamy with human nature will be large. Incentives and disincentives (moral and/or legal) may be necessary. One way to see what sorts of incentives can work is to look at an economically stratified society where they worked. Say, for example, Victorian England. To search for the peculiarities of Victorian morality that helped marriages succeed (at least in the minimal sense of not dissolving) isn't to say we should adopt those peculiarities ourselves. One can see the "wisdom" of some moral tenet — see how it achieves certain goals by implicitly recognizing deep truths about human nature — without finding it, on balance, worth the side effects. But seeing the wisdom is still a good way to appreciate the contours of the challenge it met. Looking at a Victorian marriage — Charles and Emma Darwin's — from a Darwinian point of view is worth the effort.

Before we return to Darwin's life, one caution is in order. So far we've been analyzing the human mind in the abstract; we've talked about "species-typical" adaptations designed to maximize fitness. When we shift our focus from the whole species to any one individual, we should not expect that person to chronically maximize fitness, to optimally convey his or her genes to future generations. And the reason goes beyond the one that has so far been stressed: that most human beings don't live in an environment much like the one for which their minds were designed. Environments — even the environments for which organisms are designed — are unpredictable. That is why behavioral flexibility evolved in the first place. And unpredictability, by its nature, cannot be mastered. As John Tooby and Leda Cosmides have put it, "Natural selection cannot directly 'see' an individual organism in a specific situation and cause behavior to be adaptively tailored."23

The best that natural selection can do is give us adaptations — "mental organs" or "mental modules" — that play the odds. It can give males a "love of offspring" module, and make that module sensitive to the likelihood that the offspring in question is indeed the {106} man's. But the adaptation cannot be foolproof. Natural selection can give women an "attracted to muscles" module, or an "attracted to status" module, and, what's more, it can make the strength of those attractions depend on all kinds of germane factors; but even a highly flexible module can't guarantee that these attractions translate into viable and prolific offspring.

As Tooby and Cosmides say, human beings aren't general purpose "fitness maximizers." They are "adaptation executers."24 The adaptations may or may not bring good results in any given case, and success is especially spotty in environments other than a small hunter-gatherer village. So as we look at Charles Darwin, the question isn't: Can we conceive of things he could have done to have more viable, prolific offspring than he had? The question is: Is his behavior intelligible as the product of a mind that consists of a bundle of adaptations? {107}