Dollars and Sex

by Marina Adshade

  Is the marriage system described in our model Pareto efficient or can it be improved upon by imposing monogamy, for example?

  Imposing monogamy would certainly make the man who brings the least to a marriage happier because, with that marriage institution, the woman who was initially matched with him would have to accept his marriage proposal if she wanted to be married. So he would be made better off, but she would be made worse off because that is not the decision that she would have made had she been given the option of marring a richer man. This suggests that the current system of institutionalized polygamy is Pareto efficient. It may not be perfect, someone is still unhappy, but it is as perfect as we can get given the distribution of resources.

  I should point out that if in our simple model we started instead with institutionalized monogamy, then that arrangement would also meet the criterion of Pareto efficiency. Imposing polygamy on that society may make women who would have otherwise been forced to marry men at the bottom of the resource distribution better off, certainly, but it also would make those men who now will never marry worse off.

  WHEN PROSTITUTION BECOMES PREFERABLE TO MARRIAGE

  In our model, a woman who is matched with a poor man can choose only between being his sole wife and being one of several wives of a wealthy man. There are alternatives, though, including the possibility that she could find more than one poor man (brothers for example) and marry them both. That would both give her more resources and allow all men to marry. For these reasons, it makes sense that societies that allow polygyny should also allow polyandry.

  In reality, these institutional arrangements rarely exist.

  One possible explanation, proposed by economists Lena Edlund and Evelyn Korn, is that when given the option of being either a wife with multiple husbands or one of many wives, some women would say, “No thanks. I would rather be a prostitute.”

  As we already know, polygynous marriage leaves many men unmarried. Since unmarried men would still like to have sex, however, unless they are prepared to resort to having sexual relationships with married women (which no doubt happens), the only option available for many unmarried men is to turn to prostitutes for sex.

  As a result, polygynous marriage increases the demand for prostitutes where it is prevalent and drives up the price men are willing to pay for sex. That increase in price encourages women to choose prostitution over marriage, leading to high rates of prostitution in polygynous societies and explaining why polyandry rarely exists in conjunction in polygyny.

  The idea that women who might otherwise become wives are willing to prostitute themselves when prices are sufficiently high may sound outrageous, but Steven Levitt and Sudhir Alladi Venkatesh observed over the course of their prostitution study in Chicago that when the demand for prostitutes increases over the July Fourth weekend, women who were not prostitutes before the spike in demand begin to enter the market in response to the higher pay.

  As an aside, this same logic explains why in China, where single men greatly outnumber single women, many women become prostitutes rather than marry; the excess of men in that market makes entering the sex trades profitable enough that women are willing to forgo the benefits of marriage.

  In this case, institutionalized monogamy is also Pareto efficient in the sense that if it were replaced with institutionalized polygyny, the criterion would not be met, as some individuals would become better off (the rich men and their wives) but only at the expense of making others worse off (the poor men).

  So the first point to be made here is that if a society has institutionalized polygamy, and women are freely permitted to refuse offers of marriage they do not like, then imposing monogamy helps men, but makes women worse off. This is because institutionalized monogamy forces women to marry men they would not have married had they been able to choose an alternative.

  The second point is that the more unequal the distribution of resources among men, the more incentive there is for a woman to want to be part of a polygynous household. In a polygynous household, resources have to be shared over more people, not only more wives but their children as well. So if the richest man has 50 percent more resources than the poorest man, that difference in wealth will probably not generate polygyny since the second wife would still be better off being married to the poorer man. The only condition under which a women would choose to become the second wife of the wealthy man would be one in which he has significantly more resources than poor men—at least double but probably more.

  I said earlier that the absence of polygyny in wealthy nations is a mystery, and this model illustrates why that is the case. The one characteristic of many modern-day wealthy nations is that they have very high levels of inequality. The wealthiest men in the United States, for example, are not just two or three times wealthier than the poorest men—they are hundreds of times wealthier than even those in the middle of the income distribution.

  If all that mattered to wealthy men was the number of wives they themselves had, then wealthy nations should have developed polygyny as the dominant marriage institution at some point in history. The fact that they did not requires a more sophisticated economic explanation than the one described by our model.

  IT IS A TRUTH UNIVERSALLY ACKNOWLEDGED, THAT A SINGLE MAN IN POSSESSION OF A GOOD FORTUNE MUST BE IN WANT OF A WIFE . . . OR TWO

  One possible reason for why currently wealthy nations have not adopted polygamy is that wealthy men have historically had more sons than did poor men. This is the case not just because wealthy men had more children, they did, but because successful men tended to have more sons on average than did poor men (the ratio of sons to daughters for U.S. presidents used to make a good argument for this claim, but the last three presidents (without a single son among them) have rather made a mess of those numbers). If wealthy men in the past cared about their sons’ wellbeing, they might have supported institutionalized monogamy even if they had preferred polygamy.

  Anyone who has read a historic romance novel, such as those written by Jane Austen, knows that in the past the sons of rich men did not all become rich men themselves. Economic historians like Gregory Clark and Gillian Hamilton show that the wealthier landowning class in England prior to the Industrial Revolution had more children that survived to adulthood, but that many of those children later moved into the lower economic classes; inheritance laws favored the eldest sons, leaving younger children to essentially fend for themselves.

  While a wealthy father might have preferred to have more than one wife for himself, and he might lobby for laws that would permit that arrangement, institutionalized polygyny would have reduced the probability that some of his sons, the ones who did not inherit wealth, would marry and have a family. Even if those sons did marry (after all, they did not become the poorest men in society; they just became poorer than their elder brother), polygyny would have certainly reduced the supply of women suitable to be the wife of a nobleman’s son. Polygyny would have forced each subsequent generation of men to marry women who were essentially inferior, as all the daughters born into the superior classes would be wed to only the wealthiest men.

  Just as inheritance laws that passed the bulk of a man’s estate to his oldest son prevented the dilution of the family’s assets, laws that enforced monogamy prevented the dilution of the family’s genes.

  Along the same vein, polygyny increases the demand for wives, which effectively increases the value of wives on the market. I don’t doubt that the fathers of middle- and lower-class daughters would have been happy to see their daughters marrying above their station, so to speak, but I wonder how the fathers of upper-class daughters would feel about their daughter being only one of multiple wives. Certainly their daughters would make better matches (for example, more women would have a chance to be married to the king), but the political value of a good match for a daughter is eroded when she is forced to compete with multiple wives within the same household.

  IS MONOGAMY DRIVING US TO DRINK?

  I w
ill admit this much: if I had to live in a household where my husband had more than one wife, there would have to be alcohol involved. The reality is, though, that most individuals in polygynous relationships in the developed world are part of either Mormon fundamentalist or Muslim traditions, both of which forbid the consumption of alcohol. Is there a relationship between monogamy and alcohol consumption? Is having only one spouse driving us to drink?

  Economists Mara Squicciarini and Jo Swinnen pose this question in an American Association of Wine Economists working paper and find that preindustrial societies that had polygyny as the dominant marriage institution consumed less alcohol than those societies in which monogamy was the dominant institution. They also find that as individual societies transitioned from largely polygamous to largely monogamous, alcohol consumption increased.

  Both of these facts suggest a relationship between monogamy and drinking alcohol.

  Before jumping to conclusions here, I should point out that there is no evidence that monogamy makes us drink more or that drinking makes us more monogamous. The truth is that monogamy and alcohol consumption are merely correlated, and that some third factor, most likely industrialization, is independently driving both the transition to monogamy and the increased alcohol consumption.

  We already know why monogamy is more common in industrialized economies, but it turns out that alcohol consumption is also related to industrialization. The technological innovation that goes hand in hand with industrialization makes the production of cheap alcohol possible and gives households a high-enough income to purchase things other than just the food and shelter that are needed to survive—luxuries such as alcohol. And along with industrialization comes urbanization; people who live in cities have more opportunity to consume alcohol, so that cities provided the impetus to develop a drinking culture.

  Of course, this doesn’t explain why the two dominant religions that permit polygyny also forbid alcohol consumption, but economic inquiry has its limits, and explaining religious doctrine is not a bad place to draw the line.

  This is a reasonable argument for why wealthy Western countries did not adopt polygyny in the past, but it isn’t the only one. A second is that most European countries have a long history of decentralized power, and monogamy was a gift to the masses that ensured their continued support of the ruling powers.

  George Bernard Shaw in his 1903 Maxims for Revolutionists presented this argument best when he wrote:

  “Any marriage system which condemns a majority of the population to celibacy will be violently wrecked on the pretext that it outrages morality. Polygamy, when tried under modern democratic conditions, as by the Mormons, is wrecked by the revolt of the mass inferior men who are condemned to celibacy by it; for the maternal instinct leads a woman to prefer a tenth share in a first-rate man to the exclusive possession of a third-rate one.”

  Even without democracy, it might have been smart for an authoritarian ruler to impose monogamy—if he wanted to keep his head. Economist Nils-Petter Lagerlöf developed a model that builds on the idea that an authoritarian ruler will implement laws that forbid polygyny, even at the expense of limiting himself to just one wife, if it pacifies the masses.

  As I have already said, with high levels of inequality, wealthy men will be able to have many wives because women will choose to be the second, third, or fourth wife of a rich man over being the only wife of a poor man. Being a poor man in a country in which other men are extremely rich is one thing, but being a poor man who will never be able to marry while other men have many wives is quite another. When inequality is high, both in terms of wealth and access to sex, peasants form rebellions that wreck the rulers of the country. Rulers in this situation may prefer to have multiple wives, but probably not at the expense of being beheaded by an angry mob. And so they impose monogamy on everyone in an attempt to placate poor men.

  A ruler will want to be certain that not only his rule will survive, but also the rule of his descendants. Laws can always be changed at the whim of whoever is sitting on the throne. If rulers involved the established church in the imposition of monogamy, however, they are better able to enforce those laws in the future as well as the present. By encouraging the established church to build monogamy into the moral code of a country, the current ruler could win even greater favor with his subjects than by simply passing laws that could be revoked at whim.

  All of this is in the past, and yet monogamy persists in industrialized nations today despite the widening gap in incomes between the rich and the poor. The explanation for that phenomenon hinges on the way that we value children in industrial nations and, beyond simply explaining why we do not have polygyny in the West, suggests that even if we did change our laws to permit marriages with multiple partners, the majority of households would never be polygamous even if it were legally permitted.

  THE MYSTERY THAT IS MONOGAMY

  We have a mystery, the mystery of the persistence of monogamy in the face of a widening income gap between the rich and the poor (not to be confused with the “myth of monogamy,” which is a topic for chapter 8, when we discuss infidelity). Thanks to economists Omer Moav, Eric Gould, and Avi Simhon, we have an explanation as to why Western nations have institutionalized monogamy, despite extremely high levels of inequality.

  In wealthy nations, women have the right to work and to own assets. Many women don’t depend on men to support them the way that they do in countries where women have limited access to education, employment, and property ownership. As a result, a woman in an industrialized nation is free to marry a guy who lives in a cardboard box, if she wants, without starving since she doesn’t need to depend on him for survival.

  From a modern perspective, our Monogamy Math story probably doesn’t make much sense; a woman in modern societies doesn’t have to choose between being the only wife of a poor man and being the second wife of a rich man—she can stay single if she likes and still be able to provide for herself and for her children.

  Our marriage institutions, however, were determined historically; monogamy was established long before women could go to school, earn income, or own property. So there has to be more to the explanation as to why we don’t have polygyny in industrialized countries, with high levels of income inequality among men, other than the unwillingness of modern women to enter into these arrangements.

  In the past, when almost all employment was agricultural, how much a worker earned depended more on his/her level of brawn than it did on his/her level of brains. Once countries began to industrialize, however, skills became more important, and workers with higher levels of human capital (a.k.a. education and training) began to be paid more than workers with lower levels of human capital. This change in the way in which skill was rewarded has changed the way households invest in children; industrialization has shifted household preference away from having many children, with little or no education, toward having fewer, better-educated, children.

  You will recall that in chapter 1, I mentioned that the decline in U.S. fertility rates began around 1800, at the onset of the Industrial Revolution. That decline was the direct result of the fertility decisions of parents responding to the current labor market conditions (i.e., the increased demand for semiskilled workers) by giving their children the best opportunity to earn an income in the future.

  The solution to the puzzle as to why industrialized nations have adopted monogamy lies in this difference between the wages paid to educated workers in industrial and preindustrial nations.

  In preindustrial nations, richer men typically have higher incomes than other men purely because they have access to more resources like land, for example. In terms of children, those men prefer to have many children who can work on that land and raise the income of the whole household. If the goal is to produce as many children as possible, then potential wives are not so different from each other; in fact, they are very much like the women in our Monogamy Math example.

  In industrial nations, richer men typ
ically have a higher income because they have high levels of human capital (schooling, for example). When it comes to children, those men prefer to have skilled children because they know that in the future it will be the skill level of their children that will determine their income. One way to have highly skilled children is to have a wife who is also highly skilled. Thus, industrialization increases the demand for “high-quality” wives, those who are better educated, and increases in demand have increased the value of these women on the marriage market.

  The economic argument here is, essentially, that monogamy has emerged as the dominant marriage institution because the demand for high-quality children has increased the value of high-quality women in the marriage market, making it difficult for even wealthy men to afford more than one wife.

  (To clarify this notion of the “value” of a wife, it is helpful to think of a wife’s value as determining how much bargaining power a man has to give her in order to encourage her to become his wife. If high-quality wives have high values, that implies that husbands need to give them more say in household decisions—including the decision on how many wives he will have.)

  So, while a high level of income inequality for men may encourage a society to adopt polygamy, high educational inequality for women will encourage a society to adopt monogamy. Clearly in most industrial nations the second effect, that of educated wives, has dominated the first effect, that of wealthy husbands.

  There are some interesting implications that stem from this story that we have been discussing. The first is that this can explain why wives have more bargaining power in industrialized societies where educated workers earn much higher wages. It also explains why it is that men and women prefer to marry people with similar educational levels to themselves when skilled workers are paid much higher wages than unskilled workers. Finally, it is consistent with the evidence that even in poorer countries, wealthy men with high education levels tend to marry fewer wives and have fewer children, both of which tend to be more educated, than do wealthy men with less education.