The Myth of Monogamy: Fidelity and Infidelity in Animals and People (29 page)

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hope that by studying the lives of nontechnological people, they would gain insight into the "natural," unaccommodated inclinations of
Homo sapiens,
unpolluted by MTV, computer games, air conditioning, or microwaved popcorn. Even though such efforts can easily be caricatured, there is nonetheless something meaningful about asking what human beings, deep inside, really and truly, unconstrained by civilization--or at least, minimally constrained--naturally
are.
To be sure, no one lives in a pure state of nature, but if we look both intensively and extensively at human beings, it is possible to discern some patterns that persist.

One such pattern concerns monogamy, polygamy, and EPCs.

Twenty-five hundred years ago, Plato offered an answer--albeit tongue-in-cheek--to this chapter's title question. His dialogue
The Symposium
presented this scenario, put in the mouth of the bawdy playwright Aristophenes: It seems that originally people were not as they are today, divided into male and female. Rather, they were happy, fulfilled, self-contained Androgynes, each individual consisting of four arms, four legs, two heads and sporting duplex genitalia. Each "person" was a self-contained monogamous unit. But Zeus found their smugness intolerable and-- as was his wont under such circumstances--commenced flinging thunderbolts, which split the Androgynes asunder. Since then, we have all been doomed to wander the earth, seeking to find our "other half," to reestablish that perfect, prethunderbolt state of united bliss.

(Plato's story, incidentally, has the added charm of providing an explanation for homosexuality as well
¹
as for heterosexual monogamy: Not all the original Androgynes, it seems, were truly androgynous. Some were composed of doubled female halves and some, of doubled males. Male and female homosexuals were thus generated by the same process as heterosexuals, and--like heterosexuals--they also seek ultimate satisfaction by reestablishing their preschismatic union.)

According to the Androgyne myth, monogamy--whether heterosexual or homosexual--is our natural state, our route to anatomic as well as emotional wholeness. Seen this way, Plato's tale extols monogamy. Or, alternatively, maybe it does just the opposite: explains the frequent
departures
from monogamy. Thus, maybe monogamy is natural, but only with the correct mate! If one's designated, monogamous union happens to be with the wrong half (who presumably is someone else's correct half), then EPCs are understandable efforts to locate that long-lost partner! ("Are you my missing Other?" "No? Well, how about you?")

But this myth, engaging as it may be, is not the one with which we are presently concerned. Rather, the myth of monogamy that we are seeking to

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investigate is the opposite of Plato's. It is the more widespread myth, the one claiming that in monogamous union the partners are naturally joined together, like the Androgynes before Zeus's untimely intervention. This myth, the one that not only extols monogamy but also insists on its virtual universality, is a "real" myth; that is, one that is widely held, but false.

As we shall see, the evidence is overwhelming that monogamy is no more natural to human beings than it is to other living things. First, we turn to polygyny.

The evidence includes sexual "dimorphism" combined with sexual "bimaturism." Dimorphism ("two bodies") refers to the fact that males and females are significantly different, not only in their genitals but also in basic bodily attributes, especially size. Even though some men are smaller than some women, and some women are larger than all but the largest men, men are generally larger than women, on average about 10 to 15 percent taller and heavier. (This isn't a value judgment, just a statement of statistical and biological fact.) The most likely explanation for such a disparity is that the larger sex has evolved to be larger because of the payoffs associated with success in competing with other same-sex members. And the most direct route to such a payoff is reproductive success; namely, a harem consisting of more than one female.

Looking at other living things, we find that the greater the degree of polygyny, the greater the degree of dimorphism: Certain rain-forest deer that are essentially monogamous are also monomorphic, while elk--classic harem-keepers--are highly dimorphic, with the bulls considerably larger than the cows. Similarly with members of the seal family: Monogamy and monomorphism go together, as do polygyny and dimorphism. Primates, too: Compare the dimorphic (and polygynous) gorillas, for example, with the monomorphic (and largely monogamous) marmosets.

In some primates, monogamy--or, rather, monandry, female fidelity to one male--seems remarkably persistent, despite opportunities for EPCs. In one study of free-living hamadryas baboons, for example, four out of five males in some isolated groups were vasectomized. After four years, both females associated with the intact male had given birth, whereas of the remaining six females associated with the four vasectomized males, not one had done so. Not surprisingly, male hamadryas baboons have much smaller testes relative to their body size than do the more sexually promiscuous baboons. Human beings are definitely at the big-ball end of the primate spectrum, more like chimpanzees than like gorillas or hamadryas baboons, further suggesting that we have long been accustomed to competing via our sperm as well as our bodies.

Don't be deceived, however, into thinking that human beings can easily be pigeonholed as to their "natural" way of living. Even other species

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(presumably "simpler" than
Homo sapiens)
can be so variable as to defy ready generalization. For example, in the primitive, egg-laying Australian mammals known as short-beaked echidnas, males form "mating trains" of up to 11 individuals, all neatly--and, to the human observer, comically-- lined up nose-to-tail, patiently marching along behind an estrous female, each waiting for his chance to mate with her. But this is only true in the warmer climates of northern Australia. In colder climates (e.g., in Tasmania) echidnas are monogamous. Go figure.

Nonetheless, certain basic patterns can be identified, and, in fact, doing so is much of what science is all about. A Martian biologist, sent to earth to describe its various life-forms, would have little doubt, based on sexual dimorphism alone, that
Homo sapiens
is mildly polygynous.

Added to this is the evidence from
sexual bimaturism,
the peculiar phenomenon whereby girls become women a year or two before boys become men. Like sexual dimorphism, sexual bimaturism is a consistent, species-wide trait. And like sexual dimorphism, sexual bimaturism has "polygyny" written all over it. Just as being larger and stronger conveys an advantage when it comes to same-sex competition for getting and keeping a harem, there is a payoff in being older, too. So a predictable hallmark of polygynous species is that the males delay their maturation until they are somewhat older, stronger, tougher, and presumably a bit more savvy than their more callow counterparts.

There is more evidence yet.

Men are consistently more violent than women, which again is a predictable trait of the more competitive, harem-keeping sex. A high level of aggressiveness among women carries with it relatively little payoff along with substantial possible cost, since women are unlikely to be rewarded by acquiring a "harem" of men. Biologically, there is relatively little difference between the most and the least successful women; by contrast, there is a huge difference between the most and the least successful men, especially if the mating system is polygynous. This, in turn, results in the harem-keeping sex being not only larger and later-maturing but also, on average, more aggressive. In strictly monogamous species, there is generally very little difference between the sexes when it comes to propensities for violence ... once more, because there is little to be gained and much to be lost. The harem-keeping sex, by contrast, plays a more high-stakes game and is more likely to use risky strategies; playing it safe makes sense in a world of monogamy or if one is a
harem-member.

It is tempting to conclude that male-female differences in sexual dimorphism and bimaturism--and even male-female differences in violence and risk-taking--are "hard wired" into human biology. On the other hand, cultural traditions must be acknowledged, especially when it comes to behav-

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ioral differences: Society generates expectations that men are "supposed" to act one way and women, another. In fact, even such apparently biological differences as body size and age at sexual maturation could have cultural components--if society dictates, for example, that boys should eat more than girls and thus, perhaps, grow larger. (It is more difficult-- although not impossible--to see how age at sexual maturation could be a cultural construct.)

But the idea that such differences are culturally determined founders on this hard fact: They occur cross-culturally, in societies as diverse as urban America, the highlands of New Guinea, the arctic tundra, and the islands of the South Pacific. If male-female distinctions were arbitrary productions of culture, then they should vary randomly from one society to the next. But they don't. These differences occur wherever
Homo sapiens
is found, and all of them point to a dollop of primitive polygyny as part of our biological heritage.

There is yet more evidence for an underlying pattern of human polygyny. It comes from a series of studies and observations concerning our species-wide sexual inclinations. Conducted by different researchers at different times, they converge on a few basic principles, including the fact that men, worldwide, have a much greater interest in sexual variety than do women. Once again, this makes particular sense if
Homo sapiens
is inclined to be polygynous, because a harem-keeper will have sexual relations with many women and also because, as sperm-makers, men can increase their reproductive success by doing just this. As a general rule, the male strategy has been to increase the number of sex partners rather than to have more children per partner--that is, to opt for quantity over quality.

In one study, unmarried U.S. college students were asked how many sex partners they would ideally like to have during various time intervals, from the next month to the rest of their lives. Men consistently indicated a desire for more partners than did women: During the coming year, for example, men wanted 6; women, 1. For the next three years, men wanted 10; women, 2. And as time went on, the desired difference in number of sex partners increased, until, on average, men indicated wanting 18 different sex partners over their lifetime, as compared to women's desire for 4 to 5.

Men and women were also asked to estimate the probability that they would agree to sexual intercourse with an attractive member of the opposite sex if they had known this person for one hour, one evening, a whole day, a week, a month, all the way up to five years. Men and women were equally inclined to have sex with such a person after five years, but for

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every interval short of that, men indicated a higher probability than did women. (For women, the "break-even" point was between three and six months; for men, it was about one week. Women indicated a virtually zero probability of sex after one hour, with essentially no change over the first day; even after one week, women reported themselves as very unlikely to have sex. Men said that after just one day, their likelihood of consenting would be nearly 50-50.)

These studies can be criticized for relying on what people say rather than what they actually do. Here, then, is another innovative piece of research that comes closer yet to measuring actual behavior. An attractive man or woman approached strangers of the opposite sex on a college campus and said, "I have been noticing you around campus. I find you very attractive." Then, they posed one of these three questions, selected for each subject at random: (1) "Would you go out with me tonight?" (2) "Would you come over to my apartment tonight?" (3) "Would you go to bed with me tonight?"

Of the
women
who were asked for a date, 50 percent agreed; of those asked to go to the man's apartment, 6 percent agreed; of those asked for sex, none agreed. Of the
men
who were asked for a date, approximately 50 percent said "yes" (the same as the proportion of women who had consented), whereas 69 percent agreed to go to the woman's apartment and no fewer than 75 percent agreed to go to bed with her that night! Interestingly, among the 25 percent who refused, a large number felt it necessary to explain, pointing to a previous engagement with a girlfriend and so forth.

As with other living things, both men and women are liable to suffer some costs associated with EPCs, such as increased risk of sexually transmitted diseases and other possible physical risks (notably being physically injured by the partner or--if one or both participants are already paired-- by one's own mate or the mate of the short-term partner). This latter tariff in particular is most likely to be paid by men. On the other hand, loss of reputation is a significant possible cost that falls most heavily on women: Although men can suffer if they develop a reputation of being promiscuous or unprincipled, the aura of being a Casanova or Don Juan also has its benefits, often enhancing social status among men and even, on occasion, making such a man more attractive to women.