SHEPHERD: Echo, I ween, will in the wood reply,
And quaintly answer questions: shall I try?
ECHO: Try.
What must we do our passion to express?
Press.
How shall I please her who never loved before?
Be Fore.
What most moves women when we them address?
A dress.
Say, what can keep her chaste whom I adore?
A door.
If music softens rocks, love tunes my lyre.
Liar.
Then teach me, Echo, how shall I come by her?
Buy her.
—Jonathan Swift, “A Gentle Echo on Woman”
In an astonishing study recently undertaken in Western Europe, the following facts emerged: Married females choose to have affairs with males who are dominant, older, more physically attractive, more symmetrical in appearance, and married; females are much more likely to have an affair if their mates are subordinate, younger, physically unattractive, or have asymmetrical features; cosmetic surgery to improve a male’s looks doubles his chances of having an adulterous affair; the more attractive a male, the less attentive he is as a father; roughly one in three of the babies born in Western Europe is the product of an adulterous affair.
If you find these facts disturbing or hard to believe, do not worry. The study was not done on human beings but on swallows, the innocent, twittering, fork-tailed birds that pirouette prettily around barns and fields in the summer months. Human beings are entirely different from swallows. Or are they?1
THE MARRIAGE OBSESSION
The harems of ancient despots revealed that men are capable of making the most of opportunities to turn rank into reproductive success, but they cannot have been typical of the human condition for most of its history. About the only way to be a harem-guarding potentate nowadays is to start a cult and brainwash potential concubines about your holiness. In many ways modern people probably live in social systems that are much closer to those of their hunter-gatherer ancestors than they are to the conditions of early history. No hunter-gatherer society supports more than occasional polygamy, and the institution of marriage is virtually universal. People live in larger bands than they used to, but within those bands the kernel of human life is the nuclear family: husband, wife, and children. Marriage is a child-rearing institution; wherever it occurs, the father takes at least some part in rearing the child even if only by providing food. In most societies men strive to be polygamists but few succeed. Even in the polygamous societies of pastoralists, the great majority of marriages are monogamous ones.2
It is our usual monogamy, not our occasional polygamy, that sets us apart from other mammals, including apes. Of the four other apes (gibbons, orangutans, gorillas, and chimpanzees), only the gibbon practices anything like marriage. Gibbons live in faithful pairs in the forests of Southeast Asia, each pair living a solitary life within a territory.
If men are opportunists-polygamists at heart, as I argued in the last chapter, then where does marriage come from? Although men are fickle (“You’re afraid of commitment, aren’t you?” says the stereotypical victim of a seducer), they are also interested in finding wives with whom to rear families and might well be very set on sticking by them despite their own infidelity (“You’re never going to leave your wife for me, are you?” says the stereotypical mistress).
The two goals are contradictory only because women are not prepared to divide themselves neatly into wives and whores. Woman is not the passive chattel that the tussles of despots, described in the last chapter, have implied. She is an active adversary in the sexual chess game, and she has her own goals. Women are and always have been far less interested in polygamy than men, but that does not mean they are not sexual opportunists. The eager male/coy female theory has a great deal of difficulty answering a simple question: Why are women ever unfaithful?
THE HEROD EFFECT
In the 1980s a number of women scientists, led by Sarah Hrdy, now of the University of California at Davis, began to notice that the promiscuous behavior of female chimpanzees and monkeys sat awkwardly alongside the Trivers theory that heavily female biased parental investment leads directly to female choosiness. Hrdy’s own studies of langurs and the studies of macaques by her student Meredith Small seemed to reveal a very different kind of female from the stereotype of evolutionary theory: a female who sneaked away from the troop for assignations with males; a female who actively sought a variety of sexual partners; a female who was just as likely as a male to initiate sex. Far from being choosy, female primates seemed to be initiators of much promiscuity. Hrdy began to suggest that there was something wrong with the theory rather than the females. A decade later it is suddenly clear what: A whole new light has been shed on the evolution of female behavior by a group of ideas known as “sperm competition theory.”3
The solution to Hrdy’s concern lay in her own work. In her study of the langurs of Abu in India, Hrdy discovered a grisly fact: The murder of baby monkeys by adult male monkeys was routine. Every time a male takes over a troop of females, he kills all the infants in the group. Exactly the same phenomenon had been discovered in lions a short time later: When a group of brothers wins a pride of females, the first thing they do is slaughter the innocents. In fact, as subsequent research revealed, infanticide by males is common in rodents, carnivores, and primates. Even our closest relatives, the chimpanzees, are guilty. Most naturalists, reared on a diet of sentimental natural history television programs, were inclined to believe they were witnessing a pathological aberration, but Hrdy and her colleagues suggested otherwise. The infanticide, they said, was an “adaptation”—an evolved strategy. By killing their stepchildren the males would halt the females’ milk production and so bring forward the date on which the mother could conceive once more. An alpha male langur or a pair of brother lions has only a short time at the top, and infanticide helps these animals to father the maximum number of offspring during that time.4
The importance of infanticide in primates gradually helped scientists to understand the mating systems of the five species of apes because it suddenly provided a reason for females to be loyal to one or a group of males—and vice versa: to protect their genetic investment in each other from murderous rival males. Broadly speaking, the social pattern of female monkeys and apes is determined by the distribution of their food, while the social pattern of males is determined by the distribution of females. Thus, female orangutans choose to live alone in strict territories, the better to exploit their scarce food resources. Males also live alone and try to monopolize the territories of several females. The females that live within his territory expect their “husband” to come rushing to their aid if another male appears.
Female gibbons also live alone. Male gibbons are capable of defending the home ranges of up to five females, and they could easily practice the same kind of polygamy as orangutans: one male can patrol the territories of five females and mate with them all. What is more, male gibbons are of little use as fathers. They do not feed the young, they do not protect them from eagles, they do not even teach them much. So why do they stick with one female faithfully? The one enormous danger to a young gibbon that its father can guard against is murder by another male gibbon. Robin Dunbar of Liverpool University believes that male gibbons are monogamous to prevent infanticide.5
A female gorilla is as faithful to her husband as any gibbon; she goes where he goes and does what he does. And he is faithful to her in a manner of speaking. He stays with her for many years and watches her raise his children. But there is one big difference: He has several females in his harem and is, as it were, equally faithful to each. Richard Wrangham of Harvard University believes the gorilla social system is largely designed around the prevention of infanticide but that for females there is safety in numbers. (For fruit-eating gibbons there is not enough food in a territory to feed more than one female.) So a male keeps his harem safe from the attentions of rival males and pays his children the immense favor of preventing their murder.6
The chimpanzee has further refined the anti-infanticide strategy by inventing a rather different social system. Because they eat scattered but abundant food such as fruit and spend more time on the ground and in the open, chimps live in larger groups (a big group has more pairs of eyes than a small group) that regularly fragment into smaller groups before coming back together. These “fission-fusion” groups are too large and too flexible for a single male to dominate. The way to the top of the political tree for a male chimp is by building alliances with other males, and chimp troops contain many males. So a female is now accompanied by many dangerous stepfathers. Her solution is to share her sexual favors more widely with the effect that all the stepfathers might be the father. As a result, there is only one circumstance in which a male chimp can be certain an infant he meets is not his: when he has never seen the female before. And as Jane Goodall found, male chimps attack strange females that are carrying infants and kill the infants. They do not attack childless females.7
Hrdy’s problem is solved. Female promiscuity in monkeys and apes can be explained by the need to share paternity among many males to prevent infanticide. But does it apply to mankind?
The short answer is no. It is a fact that stepchildren are sixty-five times more likely to die than children living with their true parents,8 and it is inescapable that young children often have a terror of new stepfathers that is hard to overcome. But neither of these facts is of much relevance, for both apply to older children, not to suckling infants. Their deaths do not free the mother to breed again.
Moreover, the fact that we are apes can be misleading. Our sex lives are very different from those of our cousins. If we were like orangutans, women would live alone and apart from one another. Men, too, would live alone but each would visit several women (or none) for occasional sex. If two men ever met, there would be an almighty, violent battle. If we were gibbons, our lives would be unrecognizable. Every couple would live miles apart and fight to the death any intrusion into their home range—which they would never leave. Despite the occasional antisocial neighbor, that is not how we live. Even people who retreat to their sacred suburban homes do not pretend to remain there forever, let alone keep out all strangers. We spend much of our lives on common territory, at work, shopping, or at play. We are gregarious and social.
We are not gorillas, either. If we were, we would live in seraglios, each dominated by one giant middle-aged man, twice the weight of a woman, who would monopolize sexual access to all the women in the group and intimidate the other men. Sex would be rarer than saints’ days, even for the great man, who would have sex once a year, and would be all but nonexistent for the other males.9
If we were hairless chimpanzees, our society would still look fairly familiar in some ways. We would live in families, be very social, hierarchical, group-territorial, and aggressive toward other groups than those we belong to. In other words, we would be family-based, urban, class-conscious, nationalist, and belligerent, which we are. Adult males would spend more time trying to climb the political hierarchy than with their families. But when we turn to sex, things would begin to look very different. For a start, men would take no part at all in rearing the young, not even paying child support; there would be no marriage bonds at all. Most women would mate with most men, though the top male (the president, let us call him) would make sure he had droit du seigneur over the most fertile women. Sex would be an intermittent affair, indulged in to spectacular excess during the woman’s estrus but totally forgotten by her for years at a time when pregnant or rearing a young child. This estrus would be announced to everybody in sight by her pink and swollen rear end, which would prove irresistibly fascinating to every male who saw it. They would try to monopolize such females for weeks at a time, forcing them to go away on a “consortship” with them; they would not always succeed and would quickly lose interest when the swelling went down. Jared Diamond of the University of California at Los Angeles has speculated on how disruptive this would be to society by imagining the effect on the average office of a woman turning up for work one day irresistibly pink.10
If we were pygmy chimps or bonobos, we would live in groups much like those of chimps, but there would be roving bands of dominant men who visited several groups of women. As a consequence, women would have to share the possibility of paternity still more widely, and female bonobos are positively nymphomaniac in their habits. They have sex at the slightest suggestion and in a great variety of ways (including oral and homosexual) and are sexually attractive to males for long periods. A young female bonobo who arrives at a tree where others of the species are feeding will first mate with each of the males in turn—including the adolescents—and only then get on with eating. Mating is not wholly indiscriminate, but it is very catholic.
Whereas a female gorilla will mate about ten times for every baby that is born, a female chimp will mate five hundred to a thousand times and a bonobo up to three thousand times. A female bonobo is rarely harassed by a nearby male for mating with a more junior male, and mating is so frequent that it rarely leads to conception. Indeed, the whole anatomy of male aggression is reduced in bonobos: Males are no larger than females and spend less energy trying to rise in the male hierarchy than ordinary chimps. The best strategy for a male bonobó intent on genetic eternity is to eat his greens, get a good night’s sleep, and prepare for a long day of fornication.11
THE BASTARD BIRDS
Compared to our ape cousins, we, the most common of the great apes, have pulled off a surprising trick. We have somehow reinvented monogamy and paternal care without losing the habit of living in large multimale groups. Like gibbons, men marry women singly and help them to rear their young, confident of paternity, but like chimpanzees, those women live in societies where they have continual contact with other men. There is no parallel for this among apes. It is my contention, however, that there is a close parallel among birds. Many birds live in colonies but mate monogamously within the colony. And the bird parallel brings an altogether different explanation for females to be interested in sexual variety. A female human being does not have to share her sexual favors with many males to prevent infanticide, but she may have a good reason to share them with one well-chosen male apart from her husband. This is because her husband is, almost by definition, usually not the best male there is—else how would he have ended up married to her? His value is that he is monogamous and will therefore not divide his child-rearing effort among several families. But why accept his genes? Why not have his parental care and some other male’s genes?
In describing the human mating system; it is hard to be precise. People are immensely flexible in their habits, depending on their racial origin, religion, wealth, and ecology. Nonetheless, some universal features stand out. First, women most commonly seek monogamous marriage—even in societies that allow polygamy. Rare exceptions notwithstanding, they want to choose carefully and then, as long as he remains worthy, monopolize a man for life, gain his assistance in rearing the children, and perhaps even die with him. Second, women do not seek sexual variety per se. There are exceptions, of course, but fictional and real women regularly deny that nymphomania holds any attraction for them, and there is no reason to disbelieve them. The temptress interested in a one-night stand with a man whose name she does not know is a fantasy fed by male pornography. Lesbians, free of constraints imposed by male nature, do not suddenly indulge in sexual promiscuity; on the contrary, they are remarkably monogamous. None of this is surprising: Female animals gain little from sexual opportunism, for their reproductive ability is limited not by how many males they mate with but how long it takes to bear offspring. In this respect men and women are very different.
But third, women are sometimes unfaithful. Not all adultery is caused by men. Though she may rarely or never be interested in casual sex with a male prostitute or a stranger, a woman, in life as in soap operas, is perfectly capable of accepting or provoking an offer of an affair with one man whom she knows, even if she is “happily” married at the time. This is a paradox. It can be resolved in one of three ways. We can blame adultery on men, asserting that the persuasive powers of seducers will always win some hearts, even the most reluctant. Call this the “Dangerous Liaisons” explanation. Or we can blame it on modern society and say that the frustrations and complexities of modern life, of unhappy marriages and so on, have upset the natural pattern and introduced an alien habit into human females. Call this the “Dallas” explanation. Or we can suggest that there is some valid biological reason for seeking sex outside marriage without abandoning the marriage—some instinct in women not to deny themselves the option of a sexual “plan B” when plan A does not work out so well. Call this the “Emma Bovary” strategy.
I am going to argue in this chapter that adultery may have played a big part in shaping human society because there have often been advantages to both sexes from within a monogamous marriage in seeking alternative sexual partners. This conclusion is based on studies of human society, both modern and tribal, and on comparisons with apes and birds. By describing adultery as a force that shaped our mating system, I am not “justifying” it. Nothing is more “natural” than people evolving the tendency to object to being cuckolded or cheated on, so if my analysis were to be interpreted as justifying adultery, it would be even more obviously interpreted as justifying the social and legal mechanisms for discouraging adultery. What I am claiming is that adultery and its disapproval are both “natural.”
In the 1970s, Roger Short, a British biologist who later moved to Australia, noticed something peculiar about ape anatomy. Chimpanzees have gigantic testicles; gorillas have minuscule ones. Although gorillas are four times the weight of chimps, chimps’ testicles weigh four times as much as gorillas’. Short wondered why that was and suggested that it might have something to do with the mating system. According to Short, the bigger the testicles, the more polygamous the females.12
The reason is easy to see. If a female animal mates with several males, then the sperm from each male competes to reach her eggs first; the best way for a male to bias the race in his favor is to produce more sperm and swamp the competition. (There are other ways. Some male damsel flies use their penis to scoop out sperm that was there first; male dogs and Australian hopping mice both “lock” their penis into the female after copulation and cannot free it for some time, thus preventing others from having a go; male human beings seem to produce large numbers of defective “kamikaze” sperm that form a sort of plug that closes the vaginal door to later entrants.)13 As we have seen, chimpanzees live in groups where several males may share a female, and therefore there is a premium on the ability to ejaculate often and voluminously—he who does so has the best chance of being the father. This conjecture holds up across all the monkeys and across all rodents. The more they can be sure of sexual monopoly, as the gorilla can, the smaller their testes; the more they live in multimale promiscuous groups, the larger their testes.14
It began to look as if Short had stumbled on an anatomical clue to a species’ mating system: Big testicles equals polygamous females. Could it be used to predict the mating system of species that had not been studied? For example, very little is known about the societies of dolphins and whales, but a good deal is known of their anatomy, thanks to whaling. They all have enormous testicles, even allowing for their size. The testicles of a right whale weigh more than a ton and account for 2 percent of its body weight. So, given the monkey pattern, it is reasonable to predict that female whales and dolphins are mostly not monogamous but will mate with several males. As far as is known, this is the case. The mating system of the bottle-nosed dolphin seems to consist of forcible “herding” of fertile females by shifting coalitions of males and sometimes even the simultaneous impregnation of such a female by two males at the same time—a case of sperm competition more severe than anything in the chimpanzee world.15 Sperm whales, which live in harems like gorillas, have comparatively smaller testicles; one male has a monopoly over his harem and has no sperm competitors.
Let us now apply this prediction to man. For an ape, man’s testicles are medium-sized—considerably bigger than a gorilla’s. Like a chimpanzee’s, human testicles are housed in a scrotum that hangs outside the body where it keeps the sperm that have already been produced cool, therefore increasing their shelf life, as it were.16 This is all evidence of sperm competition in man.
But human testicles are not nearly as large as those of chimps, and there is some tentative evidence that they are not operating on full power (that is, they might once have been bigger in our ancestors): Sperm production per gram of tissue is unusually low in man. All in all, it seems fair to conclude that women are not highly promiscuous, which is what we expected to find.17
It is not just monkeys, apes, and dolphins that have large testicles when faced with sperm competition. Birds do, too. And it is from birds that the clinching clue comes about the human mating system. Zoologists have long known that most mammals are polygamous and most birds are monogamous. They put this down to the fact that the laying of eggs gives male birds a much earlier opportunity to help rear his children than a male mammal ever has. A male bird can busy himself with building the nest, with sharing the duties of incubation, with bringing food for the young; the only thing he cannot do is lay the eggs. This opportunity allows junior male birds to offer females a more paternal alternative than merely inseminating them, an offer that is accepted in species that have to feed their young, such as sparrows, and rejected in those that do not feed their young, such as pheasants.
Indeed, in some birds, as we have seen, the male does all these things alone, leaving his mate with the single duty of egg laying for her many husbands. In a mammal, by contrast, there is not much he can do to help even if wants to. He can feed his wife while she is pregnant and thereby contribute to the growth of the fetus, and he can carry the baby about when it is born or bring it food when it is weaned, but he cannot carry a fetus in his belly or feed it milk when it is born. The female mammal is left literally holding the baby, and with few opportunities to help her, the male is often better off expending his energy on an attempt to be a polygamist. Only when opportunities for further mating are few and his presence increases the baby’s safety—as in gibbons—will he stay.
This kind of game-theory argument was commonplace by the mid-1970s, but in the 1980s when it became possible for the first time to do genetic blood testing of birds, an enormous surprise was in store for zoologists. They discovered that many of the baby birds in the average nest were not their ostensible father’s offspring. Male birds were cuckolding one another at a tremendous rate. In the indigo bunting, a pretty little blue bird from North America that seemed to be faithfully monogamous, about 40 percent of the babies the average male feeds in his nest are bastards.18
The zoologists had entirely underestimated an important part of the life of birds. They knew it happened, but not on such a scale. It goes under the abbreviation EPC, for extra-pair copulation, but I will call it adultery, for that is what it is. Most birds are indeed monogamous, but they are not by any means faithful.
Anders Møller is a Danish zoologist of legendary energy whom we have already met in the context of sexual selection. He and Tim Birkhead from Sheffield University have written a book that summarizes what is now known about avian adultery, and it reveals a pattern of great relevance to human beings. The first thing they proved is that the size of a bird’s testicles varies according to the bird’s mating system. They are largest in polyandrous birds, where several males fertilize one female, and it is not hard to see why. The male who ejaculates the most sperm will presumably fertilize the most eggs.
That came as no surprise. But the testicles of lekking birds, such as sage grouse, where each male may have to inseminate fifty females in a few weeks, are unusually small. This puzzle is resolved by the fact that a female sage grouse will mate only once or twice and usually with only one male. That, remember, is the whole point of female choosiness at leks. So although the master cock may need to mate with many hens, he need not waste much sperm on each because those sperm will have no competitors. It is not how often a male bird copulates that determines the size of his testicles but how many other males he competes with.
The monogamous species lie in between. Some have fairly small testicles, implying little sperm competition; others have huge testicles, as big as those of polyandrous birds. Birkhead and Møller noticed that the ones with large testicles were mostly birds that lived in colonies: seabirds, swallows, bee eaters, herons, sparrows. Such colonies give females ample opportunity for adultery with the male from the nest next door, an opportunity that is not passed up.19
Bill Hamilton believes that adultery may explain why in so many “monogamous” birds the male is gaudier than the female. The traditional explanation, suggested by Darwin, is that the gaudiest males or the best songsters get the first females to arrive, and an early nest is a successful nest. That is certainly true, but it does not explain why song continues in many species long after a male has found a wife. Hamilton’s suggestion is that the gaudy male is not trying to get more wives but more lovers. As Hamilton put it, “Why did Beau Brummel in Regency England dress up as he did? Was it to find a wife or to find an ‘affair’?”20
EMMA BOVARY AND FEMALE SWALLOWS
What’s in it for the birds? For the males it is obvious enough: Adulterers father more young. But it is not at all clear why the female is so often unfaithful. Birkhead and Møller rejected several suggestions: that she is adulterous because of a genetic side effect of the male adulterous urge, that she is ensuring some of the sperm she gets is fertile, that she is bribed by the philandering males (as seems to be the case in some human and ape societies). None of these fit the exact facts. Nor did it quite work to blame her infidelity on a desire for genetic variety. There seems to be little point in having more varied children than she would have anyway.
Birkhead and Møller were left with the belief that female birds benefit from being promiscuous because it enables them to have their genetic cake and eat it—to follow the Emma Bovary strategy. A female swallow needs a husband who will help look after her young, but by the time she arrives at the breeding site, she might find all the best husbands taken. Her best tactic is therefore to mate with a mediocre husband or a husband with a good territory and have an affair with a genetically superior neighbor. This theory is supported by the facts: Females always choose more dominant, older, or more “attractive” (that is, ornamented) lovers than their husbands; they do not have affairs with bachelors (presumably rejects) but with other females’ husbands; and they sometimes incite competition between potential lovers and choose the winners. Male swallows with artificially lengthened tails acquired a mate ten days sooner, were eight times as likely to have a second brood, and had twice as high a chance of seducing a neighbor’s wife as ordinary swallows.21 (Intriguingly, when female mice choose to mate with males other than those they “live with,” they usually choose ones whose disease-resistance genes are different from their own.)22
In short, the reason adultery is so common in colonial birds is that it enables a male bird to have more young and enables a female bird to have better young.
One of the most curious results to come out of bird studies in recent years has been the discovery that “attractive” males make inattentive fathers. Nancy Burley, whose zebra finches consider one another more or less attractive according to the color of their leg bands, first noticed this,23 and Anders Moller has since found it to be true of swallows as well. When a female mates with an attractive male, he works less hard and she works harder at bringing up the young. It is as if he feels that he has done her a favor by providing superior genes and therefore expects her to repay him with harder work around the nest. This, of course, increases her incentive to find a mediocre but hardworking husband and cuckold him by having an affair with a superstud next door.24
In any case, the principle—marry a nice guy but have an affair with your boss or marry a rich but ugly man and take a handsome lover—is not unknown among female human beings. It is called having your cake and eating it, too. Flaubert’s Emma Bovary wanted to keep both her handsome lover and her wealthy husband.
The work on birds has been conducted by people who knew little of human anthropology. In just the same way, a pair of British zoologists had been studying human beings in the late 1980s, largely in isolation from the bird work. Robin Baker and Mark Bellis of Liverpool University were curious to know if sperm competition happened inside women, and if it did, whether women had any control over it. Their results have led to a bizarre and astonishing explanation of the female orgasm.
What follows is the only part of this book in which the details of sexual intercourse itself are relevant to an evolutionary argument. Baker and Bellis discovered that the amount of sperm that is retained in a woman’s vagina after sex varies according to whether she had an orgasm and when. It also depends on how long it was since she last had sex: The longer the period, the more sperm stays in, unless she has what the scientists call “a noncopulatory orgasm” in between.
So far none of this contained great surprises; these facts were unknown before Baker and Bellis did their work (which consisted of samples collected by selected couples and of a survey of four thousand people who replied to a questionnaire in a magazine), but they did not necessarily mean very much. But Baker and Bellis also did something rather brave. They asked their subjects about their extramarital affairs. They found that in faithful women about 55 percent of the orgasms were of the high-retention (that is, the most fertile) type. In unfaithful women, only 40 percent of the copulations with the partner were of this kind, but 70 percent of the copulations with the lover were of this fertile type. Moreover, whether deliberately or not, the unfaithful women were having sex with their lovers at times of the month when they were most fertile. These two effects combined meant that an unfaithful woman in their sample could have sex twice as often with her husband as with her lover but was still slightly more likely to conceive a child by the lover than the husband.
Baker and Bellis interpret their results as evidence of an evolutionary arms race between males and females, a Red Queen game, but one in which the female sex is one evolutionary step ahead. The male is trying to increase his chances of being the father in every way. Many of his sperm do not even try to fertilize her eggs but instead either attack other sperm or block their passage.
But the female has evolved a sophisticated set of techniques for preventing conception except on her own terms. Of course, women did not know this before now and therefore did not set out to achieve it, but the astonishing thing is that if the study by Baker and Bellis proves to be right, they are doing it anyway, perhaps quite unconsciously. This, of course, is typical of evolutionary explanations. Why do women have sex at all? Because they consciously want to. But why do they consciously want to? Because sex leads to reproduction, and being the descendants of those who reproduced, they are selected from among those who want things that lead to reproduction. This is merely a form of the same argument: The typical woman’s pattern of infidelity and orgasm is exactly what you would expect to find if she were unconsciously trying to get pregnant from a lover while not leaving a husband.
Baker and Bellis do not claim to have found more than a tantalizing hint that this is so, but they have tried to measure the extent of cuckoldry in human beings. In a block of flats in Liverpool, they found by genetic tests that fewer than four in every five people were the sons of their ostensible fathers. In case this had something to do with Liverpool, they did the same tests in southern England and got the same result. We know from their earlier work that a small degree of adultery can lead to a larger degree of cuckoldry through the orgasm effect. Like birds, women may be—quite unconsciously—having it both ways by conducting affairs with genetically more valuable men while not leaving their husbands.
What about the men? Baker and Bellis did an experiment on rats and discovered that a male rat ejaculates twice as much sperm when he knows that the female he is mating with has been near another male recently. The intrepid scientists promptly set out to test whether human beings do the same. Sure enough, they do. Men whose wives have been with them all day ejaculate much smaller amounts than men whose wives have been absent all day. It is as if the males are subconsciously compensating for any opportunities for female infidelity that might be present. But in this particular battle of the sexes, the women have the upper hand because even if a man—again unconsciously—begins to associate his wife’s lack of late orgasms with a desire not to conceive his child, she can always respond by faking them.25
CUCKOLDRY PARANOIA
The cuckold, however, does not stand by and accept his evolutionary lot even unto the extinction of his genes. Birkhead and Møller think that much of the behavior of male birds can be explained by the assumption that they are in constant terror of their wives’ infidelity. Their first strategy is to guard the wife during the period when she is fertile (a day or so before each egg is laid). Many male birds do this. They follow their mates everywhere, so that a female bird who is building a nest is often accompanied on every trip by a male who never lends a hand; he just watches. The moment she is finished laying the clutch of eggs, he relaxes his vigil and begins to seek adulterous opportunities himself.
If a male swallow cannot find his mate, he often gives a loud alarm call, which causes all the swallows to fly into the air, effectively interrupting any adulterous act in progress. If the pair has just been reunited after a separation or if a strange male intrudes into the territory and is chased out, the husband will often copulate with the wife immediately afterward, as if to ensure that his sperm are there to compete with the intruder’s.
Generally it works. Species that practice effective mate guarding keep the adultery rate low. But some species cannot guard their mates. In herons and birds of prey, for example, husband and wife spend much of the day apart, one guarding the nest while the other collects food. These species are characterized by extremely frequent copulation. Goshawks may have sex several hundred times for every clutch of eggs. This does not prevent adultery, but at least it dilutes it.26
Just like herons and swallows, people live in monogamous pairs within large colonies. Fathers help to rear the young if only by bringing food or money. And crucially, because of the sexual division of labor that characterized early human hunter-gathering societies (broadly speaking, men hunt, women gather), the sexes spend much time apart. So women have ample opportunities for adultery, and men have ample incentives to guard their mates or, failing that, to copulate frequently with them.
To demonstrate that adultery is a chronic problem throughout human society, rather than an aberration of modern apartment blocks in Britain, is paradoxically difficult: first, because the answer is so stunningly obvious that nobody has studied it, and second, because it is a universally kept secret and therefore almost impossible to study. It is easier to watch birds.
Nonetheless, attempts have been made. The 570 or so Aché people of Paraguay were hunter-gatherers until 1971, living in twelve bands. They then gradually came into contact with the outside world and were lured onto government reservations run by missionaries. Today, they no longer depend on hunted meat and gathered fruit but grow most of their own food in gardens. But when they still depended on men’s hunting skills for much of their food, Kim Hill of the University of New Mexico found an intriguing pattern. Aché men would donate any spare meat they had caught to women with whom they wanted to have sex. They were not doing so to feed children they might have fathered but as direct payment for an affair. It was not easy to discover. Hill found that he was gradually forced to drop questions about adultery from his studies because the Aché, under missionary influence, became increasingly squeamish about discussing the subject. The chiefs and the head men were especially reluctant to talk about it, which is hardly surprising in view of the fact that they were the ones having the most affairs. Nonetheless, by relying on gossip Hill was able to piece together the pattern of adultery in the Aché. As expected, he found that high-ranking men were involved most, which is consistent with the idea of having your paternal-genetic cake and eating it. However, unlike in birds, it was not just the wives of low-ranking men who indulged. It is true that Aché adulterers frequently ply their mistresses with gifts of meat, but Hill thinks the most important motive is that Aché women are constantly preparing for the possibility that they will be deserted by their husbands. They are building up alternative relationships and are more likely to be unfaithful if the marriage is going badly. That is, of course, a double-edged sword: The marriage could break up because the affair is discovered.27
Whatever the motive for women, Hill and others believe that adultery has been much underemphasized as an influence in the evolution of the human mating system. In hunter-gatherer societies the male opportunist streak would have been far more easily satisfied by adultery than by polygamy. In only two known hunter-gatherer societies is polygamy either common or extreme. In the rest it is rare to find a man with more than one wife and very rare to find a man with more than two. The two exceptions prove the rule. One is among the Indians of the Pacific Northwest of America, who depended on abundant and reliable supplies of salmon and were more like farmers than hunter-gatherers in their ability to stockpile surpluses. The other is certain tribes of Australian aborigines, which practice gerontocratic polygamy: Men do not marry until they are forty, and by the age of sixty-five they have usually accumulated up to thirty wives. But this peculiar system is far from what it seems. Each old man has younger assistant men whose help, protection, and economic support he purchases by, among other things, turning a blind eye to their affairs with his wives. The old man looks the other way when the helpful nephew carries on with one of his junior wives.28
Polygamy is rare in hunter-gatherer societies, but adultery is common wherever it has been looked for. By analogy with monogamous colonial birds, therefore, one would expect to find human beings practicing either mate guarding or frequent copulation. Richard Wrangham has speculated that human beings practice mate guarding in absentia. Men keep an eye on their wives by proxy. If the husband is away hunting all day in the forest, he can ask his mother or his neighbor whether his wife was up to anything during the day. In the African pygmies Wrangham studied, gossip was rife and a husband’s best chance of deterring his wife’s affairs was to let her know that he kept abreast of the gossip. Wrangham went on to observe that this was impossible without language, so he speculated that the sexual division of labor, the institution of child-rearing marriages, and the invention of language—three of the most fundamental human characteristics shared with no other ape—all depend on another.29
WHY THE RHYTHM METHOD DOES NOT WORK
What happened before language allowed proxy mate guarding? Here, anatomy provides an intriguing clue. Perhaps the most startling difference between the physiology of a woman and that of a female chimpanzee is that it is impossible for anybody, including the woman herself, to determine precisely when in the menstrual cycle she is fertile. Whatever doctors, old wives’ tales, and the Roman Catholic Church may say, human ovulation is invisible and unpredictable. Chimpanzees become pink; cows smell irresistible to bulls; tigresses seek out tigers; female mice solicit male mice—throughout the mammal order, the day of ovulation is announced with fanfare. But not in man. A tiny change in the woman’s temperature, undetectable before thermometers, and that is all. Women’s genes seem to have gone to inordinate lengths to conceal the moment of ovulation.
With concealed ovulation came continual sexual interest. Although women are more likely to initiate sex, masturbate, have an affair with a lover, or be accompanied by their husband on the day of ovulation than on other days,30 it is nonetheless true that human beings of both sexes are interested in sex at all times of the menstrual cycle; both men and women have intercourse whenever they feel like it, without reference to hormonal events. Compared with many animals, we are astonishingly hooked on copulation. Desmond Morris called mankind “the sexiest primate alive”31 (but that was before anybody studied bonobos). Other animals that copulate frequently—lions, bonobos, acorn woodpeckers, goshawks, white ibises—do so for reasons of sperm competition. Males of the first three species live in groups that share access to females, so every male must copulate as frequently as he can or risk another male’s sperm reaching the egg first. Goshawks and white ibises do so to swamp any sperm that might have been received by the female while the male was away at work. Since it is clear that humanity is not a promiscuous species—even the most carefully organized free-love commune soon falls apart under the pressure of jealousy and possessiveness—the case of the ibis is the most pertinent for man: a monogamous colonial animal driven by the threat of adultery into the habit of frequent copulation. At least the male ibis need only keep his sex-six-times-a-day routine up for a few days each season before egg laying. Men must keep up sex twice a week for years.32
But concealed ovulation in women cannot have evolved for the convenience of the man. In the late 1970s there was a flurry of speculative theorizing about the evolutionary cause of concealed ovulation. Many of the ideas apply only to human beings. An example is Nancy Burley’s suggestion that ancestral women with unconcealed ovulation learned to be celibate when fertile because of the uniquely painful and dangerous business of human childbirth; but such women left behind no descendants, so the rare exceptions who could not detect their own ovulation mothered the human race. Yet concealed ovulation is a habit we share with some monkeys and at least one ape (the orangutan). It is also a habit we share with nearly all birds. Only our absurdly parochial anthropocentrism has allowed us to think that silent ovulation is special.
Nonetheless, it is worth going through the attempted explanations of what Robert Smith once called human “reproductive inscrutability” because they shed an interesting light on the theory of sperm competition. They come in two kinds: those suggesting concealed ovulation as a way of ensuring that fathers did not desert their young, and those suggesting the exact opposite. The first kind of argument went as follows: Because he does not know when his wife is fertile, a husband must stay around and have sex with her often to be sure of fathering her children. This keeps him from mischief and ensures he is still around to help rear the babies.33
The second kind of argument went this way: If females wish to be discriminating in their choice of partner, it makes little sense to advertise their ovulation. Conspicuous ovulation will have the effect of attracting several males, who will either fight over the right to fertilize her, or share her. If a female wishes (is designed) to be promiscuous in order to share paternity, as chimps do, or if she wishes to set up a competition so that the best male wins her, as buffalo and elephant seals do, then it pays to advertise the moment of ovulation. But if she wishes to choose one mate herself for whatever reason, then she should keep it secret.34
This idea has several variants. Sarah Hrdy proposed that silent ovulation helps prevent infanticide because neither the husband nor the lover knows if he has been cuckolded. Donald Symons thinks women use perpetual sexual availability to seduce philanderers in exchange for gifts. L. Benshoof and Randy Thornhill suggested that concealed ovulation allows a woman to mate with a superior man by stealth without deserting or alerting her husband. If, as seems possible, ovulation is less concealed from her (or her unconscious) than it is from him, then it would help her make each extramarital liaison more rewarding since she is more likely to “know” when to have sex with her lover, whereas her husband does not know when she is fertile. In other words, silent ovulation is a weapon in the adultery game.35
This intriguingly sets up the possibility of an arms race between wives and mistresses. Genes for concealed ovulation make both adultery and fidelity easier. It is a peculiar thought, and there is at present no way of knowing if it is right, but it throws into stark contrast the fact that there can be no genetic feminine solidarity. Women will often be competing with women.
SPARROW FIGHTS
It is this competition between females that provides the final clue to the reason adultery, rather than polygamy, has probably been the most common way for men to have many mates. Red-winged blackbirds, which nest in marshes in Canada, are polygamous; the males with the best territories each attract several females to nest in them. But the males with the biggest harems are also the most successful adulterers, fathering the most babies in their neighbors’ territories, too. Which raises the question of why the males’ lovers do not simply become extra wives.
There is a small owl called Tengmalm’s owl that lives in Finnish forests. In years when mice are abundant, some of the male owls have two mates, one in each of two territories, while other males go without a mate at all. The females that are married to polygamous males rear noticeably fewer young than the females married to monogamous males, so why do they put up with it? Why not leave for one of the nearby bachelors? A Finnish biologist believes that the polygamists are deceiving their victims. The females judge potential suitors by how many mice they can catch to feed them during courtship. In a good year for mice a male can catch so many mice that he can simultaneously give two females the impression that he is a fine male; he can provide each with more mice than he could catch for one in a normal year.36
Nordic forests seem to be full of deceitful adulterers, for a similar habit by a deceptively innocent-looking little bird led to a long-running dispute in the scientific literature of the 1980s. Some male pied flycatchers in the forests of Scandinavia manage to be polygamous by holding two territories, each with a female in it, like the owls or like Sherman McCoy in Tom Wolfe’s Bonfire of the Vanities who keeps an expensive wife on Park Avenue and a beautiful mistress in a rent-controlled apartment across town. Two teams of researchers have studied the birds and come to different conclusions about what is going on. The Finns and Swedes say that the mistress is deceived into believing the male is unmarried. The Norwegians say that since the wife sometimes visits the mistress’s nest and may try to drive her away, the mistress can be under no illusions. She accepts the fact that her mate may desert her for his wife but hopes that if things go wrong at the wife’s nest—they often do—he will come back to help her raise her young. He gets away with it only when the two territories are so far apart that the wife cannot visit the mistress’s territory often enough to persecute her. In other words, according to the Norwegians, men deceive their wives about their affairs, not their mistresses.37
It is not clear, therefore, whether the wife or the mistress is the victim of treachery, but one thing is certain: The bigamous male pied flycatcher has pulled off a minor triumph, fathering two broods in one season. The male has fulfilled his ambition of bigamy at the expense of a female. The wife and the mistress would both have done better had each monopolized a male rather than shared him.
To test the suggestion that it is better to cuckold a faithful husband than leave him to become the second wife of a bigamist, José Veiga studied house sparrows breeding in a colony in Madrid. Only about 10 percent of the males in the colony were polygamous. By selectively removing certain males and females he tested various theories about why more males did not have multiple wives. First, he rejected the notion that males were indispensable to the rearing of young. Females in bigamous marriages reared as many young as those in monogamous ones, though they had to work harder. Second, by removing some males and observing which males the widows chose to remarry, he rejected the idea that females preferred to mate with unmated males; they were happy to choose already mated males and to reject bachelors. Third, he rejected the idea that males could not find spare females; 28 percent of males remated with a female who had not bred in the previous year. Then he tried putting nest boxes closer together to make it easier for the male to guard two at once; he found that it entirely failed to increase the amount of polygamy. That left him with one explanation for the rarity of polygamy in sparrows: The senior wives do not stand for it. Just as male birds guard their mates, so female birds chase away and harass their husbands’ chosen second fiancées. Caged females are attacked by mated female sparrows. They do so presumably because even though they could rear the chicks on their own, it is a great deal easier with the husband’s undivided help.38
It is my contention that man is just like an ibis or a swallow or a sparrow in several key respects. He lives in large colonies. Males compete with one another for places in a pecking order. Most males are monogamous. Polygamy is prevented by wives who resent sharing their husbands lest they also share his contributions to child rearing. Even though they could bring up the children unaided, the husband’s paycheck is invaluable. But the ban on polygamous marriage does not prevent the males from seeking polygamous matings. Adultery is common. It is most common between high-ranking males and females of all ranks. To prevent it males try to guard their wives, are extremely violent toward their wives’ lovers, and copulate with their wives frequently, not just when they are fertile.
That is the life of the sparrow anthropomorphized. The life of man sparrowmorphized might read like this: The birds live and breed in colonies called tribes or towns. Cocks compete with one another to amass resources and gain status within the colony; it is known as “business” and “politics.” Cocks eagerly court hens, who resent sharing their males with other hens, but many cocks, especially senior ones, trade in their hens for younger ones or cuckold other cocks by having sex with their (willing) wives in private.
The point does not lie in the details of the sparrow’s life. There are significant differences, including the fact that human beings tend to have a much more uneven distribution of dominance, power, and resources within the colony. But they still share the principal feature of all colonial birds: monogamy, or at least pair bonds, plus rife adultery rather than polygamy. The noble savage, far from living in contented sexual equanimity, was paranoid about becoming, and intent on making his neighbor into, a cuckold. Little wonder that human sex is first and foremost in all societies a private thing to be indulged in only in secret. The same is not true of bonobos, but it is true of many monogamous birds. One reason the high bastard rates of birds came as such a shock was that few naturalists had ever witnessed an adulterous affair between two birds—they do it in private.39
THE GREEN-EYED MONSTER
Cuckoldry paranoia is deep-seated in men. The use of veils, chaperones, purdah, female circumcision, and chastity belts all bear witness to a widespread male fear of being cuckolded and a widespread suspicion that wives, as well as their potential lovers, are the ones to distrust. (Why else circumcise them?) Margo Wilson and Martin Daly of McMaster University in Canada have studied the phenomenon of human jealousy and come to the conclusion that the facts fit an evolutionary interpretation. Jealousy is a “human universal,” and no culture lacks it. Despite the best efforts of anthropologists to find a society with no jealousy and so prove that it is an emotion introduced by pernicious social pressure or pathology, sexual jealousy seems to be an unavoidable part of being a human being.
The Demon, Jealousy, with Gorgon frown
Blasts the sweet flowers of pleasure not his own,
Rolls his wild eyes, and through the shuddering grove
Pursues the steps of unsuspecting Love.40
Wilson and Daly believe that a study of human society reveals a mindset whose manifestations are diverse in detail but “monotonously alike in the abstract.” They are “socially recognized marriage, the concept of adultery as a property violation, the valuation of female chastity, the equation of ‘protection’ of women with protection from sexual contact, and the special potency of infidelity as a provocation to violence.” In short, in every age and in every place, men behave as if they owned their wives’ vaginas.41
Wilson and Daly reflect on the fact that love is an admired emotion, whereas jealousy is a despised one, but they are plainly two sides of the same coin—as anybody who has been in love can testify. They are both part of a sexual proprietary claim. As many a modern couple knows, the absence of jealousy, far from calming a relationship, is itself a cause of insecurity. If he or she is not jealous when I pay attention to another man or woman, then he or she no longer cares whether our relationship survives. Psychologists have found that couples who lack moments of jealousy are less likely to stay together than jealous ones.
As Othello learned, even the suspicion of infidelity is enough to drive a man to such rage that he may kill his wife. Othello was fictional, but many a modern Desdemona has paid with her life for her husband’s jealousy. As Wilson and Daly said: “The major source of conflict in the great majority of spouse killings is the husband’s knowledge or suspicion that his wife is either unfaithful or intending to leave him.” A man who kills his wife in a fit of jealousy can rarely plead insanity in court because of the legal tradition in Anglo-American common law that such an act is “the act of a reasonable man.”42
This interpretation of jealousy probably seems astonishingly banal. After all, it is only putting an evolutionary slant on what everybody knows about everyday life. But among sociologists and psychologists it is heretical nonsense. Psychologists have tended to see jealousy as a pathology to be discouraged and generally thought shameful—as something that has been imposed by that eternal villain “society” to corrupt the nature of man. Jealousy shows low self-esteem, they say, and emotional dependency. Indeed it does, and that is exactly what the evolutionary theory would predict. A man held in low esteem by his wife is exactly the kind of person in danger of being cuckolded, for she has the motive to seek a better father for her children. This may even explain the extraordinary and hitherto baffling fact that husbands of rape victims are more likely to be traumatized and, despite themselves, to resent their raped wives if the wife was not physically hurt during the rape. Physical hurt is evidence of her resistance. Husbands may have been programmed by evolution to be paranoidly suspicious that their wives were not raped at all, or “asked for it.”43
Cuckoldry is an asymmetrical fate. A woman loses no genetic investment if her husband is unfaithful, but a man risks unwittingly raising a bastard. As if to reassure fathers, research shows that people are strangely more apt to say of a baby, “He (or she) looks just like his father,” than to say, “He (or she) looks just like his mother”—and that it is the mother’s relatives who are most likely to say this.44 It is not that a woman need not mind about her husband’s infidelity; it might lead to his leaving her or wasting his time and money on his mistress or picking up a nasty disease. But it does imply that men are likely to mind even more about their wives’ infidelity than vice versa. History and law have long reflected just that. In most societies adultery by a wife was illegal and punished severely, while adultery by a husband was condoned or treated lightly. Until the nineteenth century in Britain, a civil action could be brought against an adulterer by an aggrieved husband for “criminal conversation.”45 Even among the Trobriand islanders, who were celebrated by Bronislaw Malinowski in 1927 as a sexually uninhibited people, females who committed adultery were condemned to die.46
This double standard is a prime example of the sexism of society and is usually dismissed as no more than that. Yet the law has not been sexist about other crimes: Women have never been punished more severely than men for theft or murder, or at least the legal code has never prescribed that they be so. Why is adultery such a special case? Because man’s honor is at stake? Then punish the adulterous man as harshly, for that is just as effective a deterrent as punishing the woman. Because men stick together in the war of the sexes? They do not do so in anything else. The law is quite explicit on this: All legal codes so far studied define adultery “in terms of the marital status of the woman. Whether the adulterous man was himself married is irrelevant.”47 And they do so because “it is not adultery per se that the law punishes but only the possible introduction of alien children into the family and even the uncertainty that adultery creates in this regard. Adultery by the husband has no such consequences.”48 When, on their wedding night, Angel Clare confessed to his new wife, Tess, in Thomas Hardy’s Tess of the D’Urbervilles, that he had sown his wild oats before marriage, she replied with relief by telling the story of her own seduction by Alec D’Urberville and the short-lived child she bore him. She thought the transgressions balanced.
“Forgive me as you are forgiven! I forgive you, Angel.”
“You—yes you do.”
“But do you not forgive me?”
“O Tess, forgiveness does not apply to the case! You were one person; now you are another. My God—how can forgiveness meet such a grotesque—prestidigitation as that!”
Clare left her that night.
COURTLY LOVE
Human mating systems are greatly complicated by the fact of inherited wealth. The ability to inherit wealth or status from a parent is not unique to man. There are birds that succeed to the ownership of their parents’ territories by staying to help them rear subsequent broods. Hyenas inherit their dominance rank from their mothers (in hyenas, females are dominant and often larger); so do many monkeys and apes. But human beings have raised this habit to an art. And they usually show a much greater interest in passing on wealth to sons than to daughters. This is superficially odd. A man who leaves his wealth to his daughters is likely to see that wealth left to his certain granddaughters. A man who leaves his wealth to his sons is likely to see the wealth left to what may or may not be his grandsons. In the few matrilineal societies there is indeed such promiscuity that men are not sure of paternity, and in such societies it is uncles that play the role of father to their nephews.49
Indeed, in more stratified societies the poor often favor their daughters over their sons. But this is not because of certainty of paternity but because poor daughters are more likely to breed than poor sons. A feudal vassal’s son had a good chance of remaining childless, while his sister was carted off to the local castle to be the fecund concubine of the resident lord. Sure enough, there is some evidence that in the fifteenth and sixteenth centuries in Bedfordshire, peasants left more to their daughters than to their sons.50 In eighteenth-century Ostfriesland in Germany, farmers in stagnant populations had oddly female-biased families, whereas those in growing populations had male-biased families. It is hard to avoid the conclusion that third and fourth sons were a drain on the family unless there were new business opportunities, and they were dealt with accordingly at birth, resulting in female-biased sex ratios in the stagnant populations.51
But at the top of society, the opposite prejudice prevailed. Medieval lords banished many of their daughters to nunneries.52 Throughout the world rich men have always favored their sons and often just one of them. A wealthy or powerful father, by leaving his status or the means to achieve it to his sons, is leaving them the wherewithal to become successful adulterers with many bastard sons. No such advantage could accrue to wealthy daughters.
This has a curious consequence. It means that the most successful thing a man or a woman can do is beget a legitimate heir to a wealthy man. Logic such as this suggests that philanderers should not be indiscriminate. They should seduce the women with the best genes and also the women with the best husbands, who therefore have the potential to produce the most prolific sons. In medieval times this was raised to an art. The cuckolding of heiresses and the wives of great lords was considered the highest form of courtly love. Jousting was little more than a way for potential philanderers to impress great ladies. As Erasmus Darwin put it:
Contending boars with tusks enamel’d strike,
And guard with shoulder shield the blow oblique;
While female bands attend in mute surprise,
And view the victor with admiring eyes.
So Knight on Knight, recorded in romance,
Urged the proud steed, and couch’d the extended lance;
He, whose dread prowess with resistless force,
Bless’d, as the golden guerdon of his toils,
Bow’d to the Beauty, and receiv’d her smiles.53
At a time when the legitimate eldest son of a great lord would inherit not only his father’s wealth but also his polygamy, the cuckolding of such lords was sport indeed. Tristan expected to inherit the kingdom of his uncle, King Mark, in Cornwall. While in Ireland he ignored the attentions of the beautiful Isolde until she was summoned by King Mark to be his wife. Panic-struck at the thought of losing his inheritance but determined to save it at least for his son, he suddenly took an enormous interest in Isolde. Or at least so Laura Betzig retells the old story.54
Betzig’s analysis of medieval history includes the idea that the begetting of wealthy heirs was the principal cause of Church-state controversies. A series of connected events occurred in the tenth century or thereabouts. The power of kings declined and the power of local feudal lords increased. As a consequence, noblemen gradually became more concerned with producing legitimate heirs to succeed to their titles, as the seigneurial system of primogeniture was established. They divorced barren wives and left all to the firstborn son. Meanwhile, resurgent Christianity conquered its rivals to become the dominant religion of northern Europe. The early Church was obsessively interested in matters of marriage, divorce, polygamy, adultery, and incest. Moreover, in the tenth century the Church began to recruit its monks and priests from among the aristocracy.55
The Church’s obsessions with sexual matters were very different from St. Paul’s. It had little to say about polygamy or the begetting of many bastards, although both were commonplace and against doctrine. Instead, it concentrated on three things: first, divorce, remarriage, and adoption; second, wet nursing, and sex during periods when the liturgy demanded abstinence; and third, “incest” between people married to within seven canonical degrees. In all three cases the Church seems to have been trying to prevent lords from siring legitimate heirs. If a man obeyed the doctrines of the Church in the year 1100, he could not divorce a barren wife, he certainly could not remarry while she lived, and he could not adopt an heir. His wife could not give her baby daughter to a wet nurse and be ready to bear another in the hope of its being a son, and he could not make love to his wife “for three weeks at Easter, four weeks at Christmas, and one to seven weeks at Pentecost; plus Sundays, Wednesdays, Fridays, and Saturdays—days for penance or sermons; plus miscellaneous feast days.” He also could not bear a legitimate heir by any woman closer than a seventh cousin—which excluded most noble women within three hundred miles. It all adds up to a sustained attack by the Church on the siring of heirs, and “it was not until the Church started to fill up with the younger brothers of men of state that the struggle over inheritance—over marriage—between them began.” Individuals in the Church (disinherited younger sons) were manipulating sexual mores to increase the Church’s own wealth or even regain property and titles for themselves. Henry VIII’s dissolution of the monasteries, following his break with Rome, which followed Rome’s disapproval of his divorcing the sonless Catherine of Aragon, is a sort of parable for the whole history of Church-state relations.56
Indeed, the Church-state controversy was just one of many historical instances of wealth-concentration disputes. The practice of primogeniture was a good way to keep wealth—and its polygamy potential—intact through the generations. But there were other ways, too. First among them was marriage itself. Marrying an heiress was always the quickest way to wealth. Of course, strategic marriage and primogeniture work against each other: If women inherit no wealth, then there is nothing to be gained from marrying a rich man’s daughter. Among the royal dynasties of Europe, though, in most of which women could inherit thrones (in default of male heirs), eligible marriages were often possible. Eleanor of Aquitaine brought Britain’s kings a large chunk of France. The War of the Spanish Succession was fought solely to prevent a French king from inheriting the throne of Spain as the result of a strategic marriage. Right down to the Edwardian practice of English aristocrats marrying the daughters of American robber barons, the alliances of great families have been a force to concentrate wealth.
Another way, practiced commonly among slave-owning dynasties in the American South, was to keep marriage within the family. Nancy Wilmsen Thornhill of the University of New Mexico has shown how in such families more often than not men married their first cousins. By tracing the genealogies of four southern families, she found that fully half of all marriages involved kin or sister exchange (two brothers marrying two sisters). By contrast, in northern families at the same time, only 6 percent of marriages involved kin. What makes this result especially intriguing is that Thornhill had predicted it before she found it. Wealth concentration works better for land, whose value depends on its scarcity, than for business fortunes, which are made and lost in many families in parallel.57
Thornhill went on to argue that just as some people have an incentive to use marriage to concentrate wealth, so other people have an incentive to prevent them from doing exactly that. And kings, in particular, have both the incentive and the power to achieve their wishes. This explains an otherwise puzzling fact: that prohibitions on “incestuous” marriages between cousins are fierce and numerous in some societies and absent in others. In every case it is the more highly stratified society that most regulates marriage. Among the Trumai of Brazil, an egalitarian people, marriage between cousins is merely frowned upon. Among the Maasai of East Africa, who have considerable disparities of wealth, such marriage is punished with “a severe flogging.” Among the Inca people, anybody having the temerity to marry a female relative (widely defined) had his eyes gouged out and was cut into quarters. The emperor was, of course, an exception: His queen was his full sister, and Pachacuti began a tradition of marrying all his half sisters as well. Thornhill concludes that these rules had nothing to do with incest but were all about rulers trying to prevent wealth concentration by families other than their own; they usually excepted themselves from such laws.58
DARWINIAN HISTORY
This kind of science goes by the name of Darwinian history, and it has been greeted with predictable ridicule by real historians. For them, wealth concentration requires no further explanation. For Darwinians, it must once have been (or must still be) the means to a reproductive end. No other currency counts in natural selection.
When we study sage grouse or elephant seals in their natural habitat, we can be fairly sure that they are striving to maximize their long-term reproductive success. But it is much more difficult to make the same claim for human beings. People strive for something, certainly, but it is usually money or power or security or happiness. The fact that they do not translate these into babies is raised as evidence against the whole evolutionary approach to human affairs.59 But the claim of evolutionists is not that these measures of success are today the tickets to reproductive success but that they once were. Indeed, to a surprising extent they still are. Successful men remarry more frequently and more widely than unsuccessful ones, and even with contraception preventing this from being turned into reproductive success, rich people still have as many or more babies as poor people.60
Yet Western people conspicuously avoid having as many children as they could. William Irons of Northwestern University in Chicago has tackled this problem. He believes that human beings have always taken into account the need to give a child a “good start in life.” They have never been prepared to sacrifice quality of children for quantity. Thus, when an expensive education became a prerequisite for success and prosperity, around the time of the demographic transition to low birthrates, people were able to read-just and lower the number of children they had in order to be able to afford to send them to school. Exactly this reason is given today by Thai people for why they are having fewer children than their parents.61
There has been no genetic change since we were hunter-gatherers, but deep in the mind of the modern man is a simple male hunter-gatherer rule: Strive to acquire power and use it to lure women who will bear heirs; strive to acquire wealth and use it to buy other men’s wives who will bear bastards. It began with a man who shared a piece of prized fish or honey with an attractive neighbor’s wife in exchange for a brief affair and continues with a pop star ushering a model into his Mercedes. From fish to Mercedes, the history is unbroken: via skins and beads, plows and cattle, swords and castles. Wealth and power are means to women; women are means to genetic eternity.
Likewise, deep in the mind of a modern woman is the same basic hunter-gatherer calculator, too recently evolved to have changed much: Strive to acquire a provider husband who will invest food and care in your children; strive to find a lover who can give those children first-class genes. Only if she is very lucky will they be the same man. It began with a woman who married the best unmarried hunter in the tribe and had an affair with the best married hunter, thus ensuring her children a rich supply of meat. It continues with a rich tycoon’s wife bearing a baby that grows up to resemble her beefy bodyguard. Men are to be exploited as providers of parental care, wealth, and genes.
Cynical? Not half as cynical as most accounts of human history.