The Moral Animal: Why We Are, the Way We Are: The New Science of Evolutionary Psychology (6 page)

The first step toward understanding the basic imbalance of the sexes is to assume hypothetically the role natural selection plays in designing a species. Take the human species, for example. Suppose you're in charge of installing, in the minds of human (or prehuman) beings, rules of behavior that will guide them through life, the object of the game being to maximize each person's genetic legacy. To oversimplify a bit: you're supposed to make each person behave in such a way that he or she is likely to have lots of offspring — offspring, moreover, who themselves have lots of offspring.

Obviously, this isn't the way natural selection actually works. It doesn't consciously design organisms. It doesn't consciously do anything. It blindly preserves hereditary traits that happen to enhance survival and reproduction.
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Still, natural selection works as if it were consciously designing organisms, so pretending you're in charge of organism design is a legitimate way to figure out which tendencies evolution is likely to have ingrained in people and other animals. In fact, this is what evolutionary biologists spend a good deal of time doing: looking at a trait — mental or otherwise — and figuring out what, if any, engineering challenge it is a solution to.

When playing the Administrator of Evolution, and trying to maximize genetic legacy, you quickly discover that this goal implies different tendencies for men and women. Men can reproduce hundreds of times a year, assuming they can persuade enough women to cooperate, and assuming there aren't any laws against polygamy — which there assuredly weren't in the environment where much of our evolution took place. Women, on the other hand, can't reproduce more often than once a year. The asymmetry lies partly in the high price of eggs; in all species they're bigger and rarer than minuscule,
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mass-produced sperm. (That, in fact, is biology's official definition of a female: the one with the larger sex cells.) But the asymmetry is exaggerated by the details of mammalian reproduction; the egg's lengthy conversion into an organism happens inside the female, and she can't handle many projects at once.

So, while there are various reasons why it could make Darwinian sense for a woman to mate with more than one man (maybe the first man was infertile, for example), there comes a time when having more sex just isn't worth the trouble. Better to get some rest or grab a bite to eat. For a man, unless he's really on the brink of collapse or starvation, that time never comes. Each new partner offers a very real chance to get more genes into the next generation — a much more valuable prospect, in the Darwinian calculus, than a nap or a meal. As the evolutionary psychologists Martin Daly and Margo Wilson have succinctly put it: for males "there is always the possibility of doing better."
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There's a sense in which a female can do better, too, but it has to do with quality, not quantity. Giving birth to a child involves a huge commitment of time, not to mention energy, and nature has put a low ceiling on how many such enterprises she can undertake. So each child, from her (genetic) point of view, is an extremely precious gene machine. Its ability to survive and then, in turn, produce its own young gene machines is of mammoth importance. It makes Darwinian sense, then, for a woman to be selective about the man who is going to help her build each gene machine. She should size up an aspiring partner before letting him in on the investment, asking herself what he'll bring to the project. This question then entails a number of subquestions that, in the human species especially, are more numerous and subtle than you might guess.

Before we go into these questions, a couple of points must be made. One is that the woman needn't literally ask them, or even be aware of them. Much of the relevant history of our species took place before our ancestors were smart enough to ask much of anything. And even in the more recent past, after the arrival of language and self-awareness, there has been no reason for every evolved behavioral tendency to fall under conscious control. In fact, sometimes it is emphatically not in our genetic interest to be aware of exactly what
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we are doing or why. (Hence Freud, who was definitely onto something, though some evolutionary psychologists would say he didn't know exactly what.) In the case of sexual attraction, at any rate, everyday experience suggests that natural selection has wielded its influence largely via the emotional spigots that turn on and off such feelings as tentative attraction, fierce passion, and swoon-inducing infatuation. A woman doesn't typically size up a man and think: "He seems like a worthy contributor to my genetic legacy." She just sizes him up and feels attracted to him — or doesn't. All the "thinking" has been done — unconsciously, metaphorically — by natural selection. Genes leading to attractions that wound up being good for her ancestors' genetic legacies have flourished, and those leading to less productive attractions have not.

Understanding the often unconscious nature of genetic control is the first step toward understanding that — in many realms, not just sex — we're all puppets, and our best hope for even partial liberation is to try to decipher the logic of the puppeteer. The full scope of the logic will take some time to explain, but I don't think I'm spoiling the end of the movie by noting here that the puppeteer seems to have exactly zero regard for the happiness of the puppets.

The second point to grasp before pondering how natural selection has "decided" to shape the sexual preferences of women (and of men) is that it isn't foresightful. Evolution is guided by the environment in which it takes place, and environments change. Natural selection had no way of anticipating, for example, that someday people would use contraception, and that their passions would thus lead them into time-consuming and energy-sapping sex that was sure to be fruitless; or that X-rated videotapes would come along and lead indiscriminately lustful men to spend leisure time watching them rather than pursuing real, live women who might get their genes to the next generation.

This isn't to say that there's anything wrong with "unproductive" sexual recreation. Just because natural selection created us doesn't mean we have to slavishly follow its peculiar agenda. (If anything, we might be tempted to spite it for all the ridiculous baggage it's saddled us with.) The point is just that it isn't correct to say that people's minds are designed to maximize their fitness, their genetic
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legacy. What the theory of natural selection says, rather, is that people's minds were designed to maximize fitness in the environment in which those minds evolved. This environment is known as the EEA — the environment of evolutionary adaptation.
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Or, more memorably: the "ancestral environment." Throughout this book, the ancestral environment will lurk in the background. At times, in pondering whether some mental trait is an evolutionary adaptation, I will ask whether it seems to be in the "genetic interest" of its bearer. For example: Would indiscriminate lust be in the genetic interest of men? But this is just a kind of shorthand. The question, properly put, is always whether a trait would be in the "genetic interest" of someone in the EEA, not in modern America or Victorian England or anywhere else. Only traits that would have propelled the genes responsible for them through the generations in our ancestral social environment should, in theory, be part of human nature today.
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What was the ancestral environment like? The closest thing to a twentieth-century example is a hunter-gatherer society, such as the !Kung San of the Kalahari Desert in Africa, the Inuit (Eskimos) of the Arctic region, or the Ache of Paraguay. Inconveniently, hunter-gatherer societies are quite different from one another, rendering simple generalization about the crucible of human evolution difficult. This diversity is a reminder that the idea of a single EEA is actually a fiction, a composite drawing; our ancestral social environment no doubt changed much in the course of human evolution.
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Still, there are recurring themes among contemporary hunter-gatherer societies, and they suggest that some features probably stayed fairly constant during much of the evolution of the human mind. For example: people grew up near close kin in small villages where everyone knew everyone else and strangers didn't show up very often. People got married — monogamously or polygamously — and a female typically was married by the time she was old enough to be fertile.

This much, at any rate, is a safe bet: whatever the ancestral environment was like, it wasn't much like the environment we're in now. We aren't designed to stand on crowded subway platforms, or to live in suburbs next door to people we never talk to, or to get hired or fired, or to watch the evening news. This disjunction between the contexts of our design and of our lives is probably responsible
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for much psychopathology, as well as much suffering of a less dramatic sort. (And, like the importance of unconscious motivation, it is an observation for which Freud gets some credit; it is central to his Civilization and Its Discontents.)

To figure out what women are inclined to seek in a man, and vice versa, we'll need to think more carefully about our ancestral social environment(s). And, as we'll see, thinking about the ancestral environment also helps explain why females in our species are less sexually reserved than females in many other species. But for purposes of making the single, largest point of this chapter — that, whatever the typical level of reserve for females in our species, it is higher than the level for males — the particular environment doesn't much matter. For this point depends only on the premise that an individual female can, over a lifetime, have many fewer offspring than an individual male. And that has been the case, basically, forever: since before our ancestors were human, before they were primates, before they were mammals — way, way back through the evolution of our brain, down to its reptilian core. Female snakes may not be very smart, but they're smart enough to know, unconsciously, at least, that there are some males it's not a good idea to mate with.

Darwin's failure, then, was a failure to see what a deeply precious commodity females are. He saw that their coyness had made them precious, but he didn't see that they were inherently precious — precious by virtue of their biological role in reproduction, and the resulting slow rate of female reproduction. Natural selection had seen this — or, at least, had "seen" it — and female coyness is the result of this implicit comprehension.

The first large and clear step toward human comprehension of this logic was made in 1948 by the British geneticist A. J. Bateman. Bateman took fruit flies and ran them through a dating game. He would place five males and five females in a chamber, let them follow their hearts, and then, by examining the traits of the next generation, figure out which offspring belonged to which parents. He found a clear pattern. Whereas almost all females had about the same number of offspring, regardless of whether they mated with one, two, or
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three males, male legacies differed according to a simple rule: the more females you mate with, the more offspring you have. Bateman saw the import: natural selection encourages "an undiscriminating eagerness in the males and a discriminating passivity in the females."
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Bateman's insight long lay essentially unappreciated. It took nearly three decades, and several evolutionary biologists, to give it the things it lacked: full and rigorous elaboration on the one hand, and publicity on the other.

The first part — the rigor — came from two biologists who are good examples of how erroneous some stereotypes about Darwinism are. In the 1970s, opposition to sociobiology often took the form of charges that its practitioners were closet reactionaries, racists, fascists, etcetera. It is hard to imagine two people less vulnerable to such charges than George Williams and Robert Trivers, and it is hard to name anyone who did more than they to lay the foundations of the new paradigm.

Williams, a professor emeritus at the State University of New York, has worked hard to dispel vestiges of social Darwinism, with its underlying assumption that natural selection is a process somehow worthy of obedience or emulation. Many biologists share his view, and stress that we can't derive our moral values from its "values." But Williams goes further. Natural selection, he says, is an "evil" process, so great is the pain and death it thrives on, so deep is the selfishness it engenders.

Trivers, who was an untenured professor at Harvard when the new paradigm was taking shape and is now at Rutgers University, is much less inclined than Williams toward moral philosophy. But he evinces an emphatic failure to buy the right-wing values associated with social Darwinism. He speaks proudly of his friendship with the late Black Panther leader Huey Newton (with whom he once co-authored an article on human psychology). He rails against the bias of the judicial system. He sees conservative conspiracies where some people don't.

In 1966 Williams published his landmark work,
Adaptation and Natural Selection: A Critique of Some Current Evolutionary Thought
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Slowly this book has acquired a nearly holy stature in its field. It is a basic text for biologists who think about social behavior, including human social behavior, in light of the new Darwinism.
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Williams's book dispelled confusions that had long plagued the study of social behavior, and it laid down foundational insights that would support whole edifices of work on the subjects of friendship and sex. In both cases Trivers would be instrumental in building the edifices.

Williams amplified and extended the logic behind Bateman's 1948 paper. He cast the issue of male versus female genetic interests in terms of the "sacrifice" required for reproduction. For a male mammal, the necessary sacrifice is close to zero. His "essential role may end with copulation, which involves a negligible expenditure of energy and materials on his part, and only a momentary lapse of attention from matters of direct concern to his safety and well-being." With little to lose and much to gain, males can profit, in the currency of natural selection, by harboring "an aggressive and immediate willingness to mate with as many females as may be available." For the female, on the other hand, "copulation may mean a commitment to a prolonged burden, in both the mechanical and physiological sense, and its many attendant stresses and dangers." Thus, it is in her genetic interest to "assume the burdens of reproduction" only when circumstances seem propitious. And "one of the most important circumstances is the inseminating male"; since "unusually fit fathers tend to have unusually fit offspring," it is "to the female's advantage to be able to pick the most fit male available...."
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