The Myth of Monogamy: Fidelity and Infidelity in Animals and People (27 page)

Sexual conflict generally occurs when the reproductive success of one sex is enhanced by something that reduces the reproductive success of the other. Males accordingly seek to minimize sperm competition, as by mate-guarding, whereas females try to promote it. Among dunnocks, an alpha male mate-guards to protect his paternity, whereas a female attempts to

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escape the guarding alpha male and actively encourages copulation attempts by beta males, probably so as to induce the beta male to assist with rearing her chicks (by increasing the probability that they might also be his).

Among mammals, we have considered the possibility that reproductive synchrony may be a female counteradaptation to polygyny, making it more difficult for a single harem-keeper to inseminate--or even to guard--all the fertilizable females. Insofar as synchrony enhances opportunities for females to engage in EPCs, it is likely to be in the interests of females but counter to the interests of males.

Then there is the matter of copulatory plugs: Males and females have a shared interest in preventing a male's sperm from leaking out. (This assumes, of course, that the inseminating male was chosen by the female in question and did not coerce the copulation.) But perspectives probably differ on whether it is desirable to keep other males from getting in! Hence, it may be worth noting that female fox squirrels as well as eastern gray squirrels have been observed removing copulatory plugs from their vaginas-- either discarding or eating them--within 30 seconds of copulating. Male squirrels would presumably prefer their sexual partners to leave these plugs in place, but there is probably little they can do about it.

In many animals, males prefer to mate with virgins. This way, they gain a higher confidence of paternity. In addition, among species such as the scor-pionflies in which males provide a metabolically valuable nuptial gift, a male whose partner is engaging in sex for the first time is guaranteed that his investment will go toward nourishing eggs fertilized by him rather than by some preceding male. But females are likely to see things differently, since they can gain extra nutrients by mating with more than one male. Among bush crickets--another insect species--males cannot distinguish virgins from nonvirgins, because females have evidently evolved means of disguising chemical and physical cues as to their erotic history. Not to be entirely outdone, however, male bush crickets have adopted another tactic to assess the sexual desirability of would-be mates: They evaluate females by age, preferring those that are younger, since all other things being equal, younger individuals are less likely to have already mated. (Of course, a preference for virgins--as marriage partners, as opposed to one-night stands--is not limited to nonhuman animals. Among many human societies, it is still considered a major transgression for a woman to have lost her virginity before marriage; indeed, there is a cross-cultural tradition that voids a marriage if the bride is not a virgin. Physicians in Japan and--more covertly--in the Middle East have long had a booming business re-creating virgins via plastic surgery.)

When it comes to male-female reproductive conflict, there is a pattern that goes even beyond the infamous double standard; namely, sexual coercion. Coercive sexual practices are generally one-way affairs, imposed by

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males on females, with rape only the most extreme form. And rape has few if any implications for monogamy. By contrast, there is room for members of one sex--usually, but not always, males--to induce females to cease their wandering ways and accept monogamy in return for certain promises, generally promises involving parental care.

Biologist Patricia Gowaty introduces the novel and milder concept of "helpfully coercive" males, individuals who manipulate females into mating with them by helping the females rear offspring. In some cases, the benefits of such help may not be sufficiently great to make up for the lost genetic benefits potentially obtained via EPCs, and females will resist sexual monogamy or else follow this time-honored strategy: Enter into social monogamy but engage in EPCs on the sly.

Those females with a lot to lose if the male withdraws his assistance are most likely to be coerced (or, to put it more kindly, seduced) by male offers of parental helpfulness. Similarly for those females with relatively little to gain via EPCs; that is, if there are only minor differences in genetic quality among available males. It is also possible that high-quality females are especially able to succeed in child-rearing without male help. If so, then these high-quality females--being less fearful of losing male assistance--should be especially liberated to seek extra-pair sex. This, in turn, might provide a novel explanation for why broods with EPC-produced young often have a higher success rate: not so much because extra-pair males provide especially good food, genes, protection, or anything else, but simply because these broods are produced by "superfemales," who, buttressed by their superiority, are capable of disregarding the helpfully coercive efforts of their husbands to keep them at home.

Not that males don't typically try to keep their mates in thrall, often indirectly. Males who compete successfully for choice real estate, for example, may be doing so in an effort to prevent their eventual mates from looking elsewhere for mating opportunities. As a result, it is possible that such females are thereby seduced into mating with males of relatively low genetic quality. But this is unlikely, since, in all probability, high-quality males-- because of their high quality--are successful in male-male competition for resources, too. Pair-bonds can, nonetheless, become pair bondage, even without direct physical coercion.

If there are no winners in a world of male-female sexual conflicts, it may be reassuring to note that there probably are no clear losers, either. Adaptations beget counteradaptations, measures generate countermeasures, and in any sexually reproducing species, every reproduction represents a precise, mathematically equal triumph for one male and one female. So, although individuals win or lose, males and females overall do equally well. (Technically, males in general are exactly as "fit" as are females in general.) Biologist Leigh van Valen introduced the "Red Queen hypothesis" as a new

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evolutionary law: Recall the scene when the Red Queen of Wonderland instructs Alice that with the world moving so rapidly, everyone must run just to stay in place ... and to get anywhere, it is necessary to run twice as fast! The Red Queen hypothesis states that for systems--such as males and females--that are inextricably tied together, "winning" by one side necessarily generates a compensating response by the other. No matter how fast or how far we run, we are all in the same boat.

"Text: human beings. As we shall see in the next chapter, monogamy

is not natural to our own species. And indeed, it is much less com-

JL ^1
mon than a naive, sentimental view of "marriage and the family" would suggest. But it does occur, and we must ask why.

The short answer is that no one knows. There has, however, been a lot of interesting speculation, not all of it from biologists. In
The Origin of the Family, Private Property and the State,
Friedrich Engels (best known for his collaboration with Karl Marx in writing
The Communist Manifesto)
developed one theory, traceable at least to Rousseau and perhaps to earlier origins. In the beginning, according to this speculation, there were no exclusive social or sexual relationships. Children belonged to everyone. Then came the initial worm in that Edenic apple: private property. WTioever had it wanted to pass it on to his descendants, but with "omnigamy"--everyone copulating with everyone--whose children were whose? The solution was monogamy, whereby men could control the sexuality of women, thereby insuring heirs and validating their property interests.

Engels missed some important points. First,
why
would men be concerned with establishing property rights for their heirs at all? (Because of the deep-seated biological inclination to favor one's genetic relatives, or, to put it in "selfish-gene" language, because genes tend to favor copies of themselves in those bodies that we call "children"?) And second, both Engels and Rousseau before him almost certainly got it backwards: Men don't dominate women so as to protect their property. More likely, they accumulate property--as well as prestige and power of other sorts--so as to attract women.

There have been several other theories to account for the origin of human monogamy. Another nonbiological one was developed by pioneer sociologist Thorstein Veblen, in
The Theory of the Leisure Class.
Veblen attributed much social behavior to a need for self-display, including the accumulation of women. For a man to "have" a woman--and better yet, many women-- is a clear sign that he is powerful and successful. And in turn, according to Veblen, "the practice of seizing women from the enemy as trophies gave rise to a form of ownership-marriage." Women were primordial property.

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Other ideas reflect more evolutionary sophistication. Thus, we have already considered how the rapid growth, of young birds--typically combined with the utter helplessness of many nestlings--seems correlated with avian monogamy... such as it is. Human infants grow more slowly than infant birds, but they are, if anything, even more helpless at birth, and they remain profoundly needy for a very long time. Under these conditions, it is reasonable that mothers, and even fathers, would be predisposed to shared parenting, quite literally for the sake of the kids.

The likely connection to monogamy would doubtless go beyond a shared male-female interest in cooperative parenting: To some extent, males can be expected to insist that in return for fathering--and not mere inseminating--they are offered a high confidence of paternity. And, in fact, although human beings are perfectly good mammals, we are also unusual in our fathering.

Aside from pregnancy and lactation, there is nothing that mothers do that fathers can't. Nonetheless, even though paternal care is better developed and more frequent in human beings than in most other mammals, it is not all that prominent even in our own species. A survey of paternal behavior in 80 different societies reported a close father-infant relationship in only 4 percent of them. And even in these cases, fathers spent less than 15 percent of their time actively engaged with infants. Moreover, when they do interact, much of what transpires is play rather than caretaking as such. On the other hand, even though fathers consistently do less fathering than mothers do mothering, there is evidence that what they do may be quite important. Among the Ache Indians of South America, for example, a child is relatively safe and secure if he or she has a father: Up to age 15, such a child suffers only a 0.6% chance of dying. On the other hand, a child under age 15 and lacking a father suffers a 9.1% risk of death.

Given that there can be a real payoff to having a dedicated male caretaker, it is not a great stretch to consider that there may also be a benefit-- to the offspring, and thus to both parents--in monogamy. After all, monogamy means that a male, no less than a female, is available for child care. On the other hand, if the issue is protection and access to resources, then it stands to reason that a powerful, wealthy polygynist could in theory provide as much to each of his many wives and their offspring as could a less impressive, impoverished man, even if the latter is devotedly monogamous.

Monogamy is widely seen as benefiting women, while it is often assumed that polygyny is a patriarchal, male-dominated system that oppresses women. But it is easy to forget that for every successful polygynist man, there are several unsuccessful bachelors; since there are roughly equal numbers of men and women, if one man has ten wives, for example, then there are nine without wives at all. Focusing on the high achievers is reminiscent

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of those people who claim to remember their previous lives: For some reason, their recollections always involve a prior existence as Napoleon, Joan of Arc, one of the pharaohs or queens of Egypt, or a medieval lord or lady . .. never as a serf, slave, or peasant!

It may be that, in fact, polygyny is a disaster for most men and, comparatively speaking, a good deal for most women. With polygyny, more women have the option of associating themselves with a powerful, successful man. For subordinate, less successful men, it is a serious problem, but very few women are likely to be shut out. Thus, although we often think of monogamy as benefiting women, it may be far more congenial for
men,
especially those in the middle or lower ranks. Monogamy is the great male equalizer, a triumph of domestic democracy.