Shadows of Forgotten Ancestors (46 page)

Odds anywhere approaching 200-million-to-1 in every conception, continued once a generation through geological ages, imply an extremely strong selection of sperm. Leaner, more streamlined sperm cells with more swiftly lashing flagellas that can swim straight and that have superior chemical sensors will probably arrive first; but that has very little to do with the characteristics, once grown up, of the individual so conceived. Getting to the egg first with genes for
boorishness, say, or stupidity, seems a dubious evolutionary benefit. A great deal of effort would appear to be squandered in natural selection among the sperm cells.
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But then it seems odd that so many sperm cells are dysfunctional. We do not understand why this should be.

Many other factors affect which sperm succeeds: Who’s conceived must depend on the progress of the egg into the fallopian tubes, the precise moment of ejaculation, the position of the parents, their rhythm of motion, subtle distractions or encouragements, cyclical hormonal and metabolic variables, and so on. At the heart of reproduction and evolution, again we find a surprisingly strong random component.

The monkeys and apes are preeminent among animals where many males mate, one after the other, with the same female. They can hardly contain themselves, jumping up and down with excitement, awaiting their turn. In chimpanzees, as we’ve noted, there may be dozens of copulations in quick succession with an ovulating female. So the act itself cannot be prolonged or rich in nuance. Several pelvic thrusts, roughly one a second, and it’s over. For an average male there’s a copulation maybe once an hour, all the livelong day. For females in estrus it’s much more than that.

In ten or twenty minutes many males may have copulated with the same female. So consider the sperm cells of these various male chimps, racing against one another. Essentially, they set out from the same starting line. The probability of insemination by a given male is proportional to the number of sperm cells delivered, other things being equal; and thus the chimps with the largest number of sperm cells per ejaculation, the chimps able to copulate the most times in succession before exhaustion sets in, have an advantage. Having more sperm cells requires larger testicles. The very large testicles of male chimps amount to about a third of a percent of their entire body weight—twenty or more times the endowment, relatively speaking, of primates who are monogamous or who live in breeding units of one male and several females. In general it is found that males have considerably larger testicles for their body size in species where many males mate with each female. Not only is there selection for testicular volume, but also for an interest in copulation. This may be one of the routes—there are many mutually reinforcing trajectories, as we’ve
described—to the highly sexual social proclivities of our primate order. Because men, compared to male chimps, have such relatively small testicles, we might guess that promiscuous societies were uncommon in the immediate human past. But a few million years ago, say, our ancestors may have been substantially more indiscriminate sexually and substantially better endowed.

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Chimpanzee females and their young have deep bonds of affection, while the adolescent and adult males seem more often mesmerized by rank and sex. The young revel in rough-and-tumble play together. Infants whimper and scream if they find themselves out of sight of their mothers. Youngsters will come to the aid of their mother if she is being attacked, and vice versa. Siblings may show each other special, affectionate consideration throughout their lives, and take care of the young during childhood if—as is common—the mother has died before the children are grown. Occasionally chimps of either sex will endanger themselves to help others, even those who are not close relatives. Male bonding on a hunt or patrol is palpable. Clearly there are opportunities—especially when the testosterone titers are low—for civil, affectionate, even altruistic behavior in chimpanzee society.

Adult males, despite the dominance hierarchy, spend considerable time alone. After the birth of their first baby or two, most females spend their entire lives with others. So females are both required to develop more refined social skills and have more opportunity to do so. As is usual among monkeys and apes—with rare exceptions—only one child is born at a time. Except when they’re in estrus, their time is spent mainly with the children. This is key for the next generation: As we’ve mentioned, apes and monkeys that are not regularly cared
for, nursed, held, fondled, and groomed by an adult tend to become socially awkward, sexually inept, and disastrous as parents when they grow up.

Females are not born knowing how to be competent mothers; they must be taught by example. The investment of time required of the mother is substantial: The young are not weaned until they’re five or six years old, and enter puberty around age ten. For much of the time until weaning they’re unable to care for themselves. They’re very good, though, in clutching their mother’s hair as they ride upside-down on her belly and chest. So long as they allow the infant to nurse whenever it wants, perhaps several times an hour, chimp mothers are usually infertile, and unattractive to males. This is called “lactational anestrus.” Without the males constantly hassling them for sex, they’re able to spend much more time with the kids.

Chimp mothers use corporal punishment only very rarely. Infants learn the conventional modes of threat and coercion by closely observing older male role models. Infant males soon attempt to intimidate females. This may take some effort; females, especially high-status females, may not take kindly to being bullied by some young whippersnapper. The upstart’s mother may help him in his efforts at intimidation. But before reaching adulthood nearly every male has obtained submission from nearly every female. Nursing male infants—including those still years away from weaning—routinely and successfully copulate with adult females. Adolescent males emulate adult males carefully (aping every nuance of their intimidation displays, for example), wish to be their apprentices and acolytes, are simultaneously nervous and submissive and hopeful in their presence. They’re looking for heroes to worship. It even happens that an adolescent who’s been cruelly attacked by an adult male will leave his mother and follow the aggressor everywhere, submission signals flashing, longing for acceptance at some future and glorious time.

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From a human perspective chimpanzee social life has many nightmarish flourishes. And yet, despite its excesses, it’s hauntingly familiar. Many spontaneous groupings of men are oriented around hierarchy, combat, blood sports, and loveless sex. The combination
of dominant males, submissive females, differential but scheming subordinates, a driving hunger for “respect” up and down the hierarchy, the exchange of current favors for future loyalty, barely submerged violence, protection rackets, and the systematic sexual exploitation of all available adult females, has some marked points of similarity with the lifestyles and ambiance of absolute monarchs, dictators, big-city bosses, bureaucrats of all nations, gangs, organized crime, and the actual lives of many of the figures in history adjudged “great.”

The horrors of everyday life among the chimpanzees recall similar events in our history. We find humans behaving like chimps at their worst in endless succession in the daily press, in modern popular fiction, in the chronicles of the most ancient civilizations, in the sacred books of many religions, and in the tragedies of Euripides and Shakespeare. A summary of human nature based on the plays of Shakespeare would define “man,” wrote Hippolyte Taine, as

We’re not descended from chimps (or vice versa); so there’s no necessary reason why any particular chimp trait need be shared by humans. But they’re so closely related to us that we might reasonably guess that we share many of their hereditary predispositions—perhaps more effectively inhibited or redirected, but smoldering in us nevertheless. We’re constrained by the rules that, through society, we impose on ourselves. But relax the rules, even hypothetically, and we can see what’s been churning and fermenting inside us all along. Beneath the elegant varnish of law and civilization, of language and sensibility—remarkable accomplishments, to be sure—just how different from chimpanzees are we?

For example, consider the crime of rape. Many men find depictions of rape arousing—especially if the woman is portrayed as enjoying it despite her initial resistance. Most American high school and college students (of both sexes) believe that a man is justified in forcing a woman to have sex—at least when the woman behaves provocatively.
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More than a third of American college men acknowledge
some propensity to commit rape if they were guaranteed they could get away with it.
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The percentage goes up if some euphemism such as “force” appears in the question instead of “rape.” The actual risk of an American woman being raped in her lifetime is at least one chance in seven; almost two-thirds of the victims have been raped when they were minors.
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Perhaps men in other nations are less fascinated with rape than Americans are; perhaps mature men, with lower testosterone titers, are less comfortable with rape than adolescents are.
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But it would be hard to argue that there’s no biological predisposition for men to rape.

While a range of causal factors have been proposed, most rapists turn out to be not slavering psychopaths, but ordinary men given the opportunity and acting on impulse,
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sometimes repeatedly and compulsively. Some students of the subject see rape as a biological strategy (entered into without his conscious understanding) to propagate the rapist’s genes;
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others see it as a means for men (again largely unconsciously) to maintain through intimidation and violence their domination over women.
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The two explanations do not seem mutually exclusive; and both seem to be operative in chimp society. Also, a significant minority of women are aroused by fantasies of rape, and, in one study, women who have been raped by an acquaintance seem disturbingly more likely to continue dating their assailants than those who were subjected only to attempted rape by an acquaintance.
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This is at least reminiscent of the compliance pattern of female chimps.

Over a set of hereditary predispositions human society lays down a kind of stencil that permits some to be fully expressed, some partially, and some hardly at all. In cultures where women have roughly comparable political power with men rape is rare or absent.
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However strong any genetic propensity toward rape might be, social parity appears to be a highly effective antidote. Depending on the structure of the society, many different brews of human proclivities can be elicited.

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Chimpanzee society has an identifiable set of rules that most of its members live by: They submit to those of higher rank. Females defer to males. They cherish their parents. They care for their young. They have a kind of patriotism, and defend the group against outsiders.
They share food. They abhor incest. But they have, so far as is known, no lawgivers. There are no stone tablets, no sacred books in which a code of conduct is laid out. Nevertheless, there is something like a code of ethics and morals operating among them—one that many human societies would find recognizable and, as far as it goes, congenial.