Shadows of Forgotten Ancestors (45 page)

In chimpanzee etiquette, the correct response to the male courtship display is to crouch down on the ground and lift your behind invitingly. If the social niceties should elude you at first, the male will shortly set you straight. Recalcitrant females are attacked. All males in the group expect sexual access to all females, subject to necessary exclusions enforced by jealous, higher-ranking males. (Adolescent females are available for copulation even to infant males, who are sometimes ardent lovers.) Again, a significant exception is mothers and sons; although the son may give it a try, the mother tends to resist vigorously.

It’s natural for us to think of the instant submission and compliance of these female apes as exacted under threat of bodily harm, as rape pure and simple, even if the female is not bitten or bruised. But this cannot be the whole story, because female primates raised alone will, on going into first estrus, present themselves readily to many passing males, to humans, and, occasionally, even to furniture. Not just some degree of compliance is hardwired and built in, but so is real sexual enthusiasm. As in the hamsters-in-motorcycle-jackets experiment, the females, if given a chance, often show a marked preference for the higher-ranking males: The Big Guy, he’s all right. Perhaps also the males present themselves to those of higher rank not so much as a humiliating means of social advancement but because they genuinely enjoy submission.

As with most animals, the chimp male enters the female’s vagina from behind. Often the male is in a crouching or seated position, with his hands on her waist or buttocks as she positions herself on him. To a human observer their faces are strangely expressionless. Much has been made about the difference between chimp and human sexual practices—almost certainly in an attempt to deny the closeness of the kinship. But the favorite ancient Roman sexual practice was chimp-like, the male seated on a small stool and the female, often her back to his front, settling herself down on him. The style of our hunter-gatherer
ancestors (if we may judge from contemporary examples) is also more like the chimps: They are often recumbent on their sides, the male embracing the female from behind. As a fashionable human sexual practice, perhaps the “missionary position” is not much older than missionaries—although, as we’ll see later, there’s one other animal that adopted it long before they did.

By human standards chimp sexual life is a perpetual open-air orgy—compulsive, unending, and always with the male grasping the female from behind. The average copulation rate is one or two an hour. Every hour. For each mature chimp. In estrus, of course, it’s more. When the females are ovulating and able to be impregnated, their vulvas and allied nether parts swell extravagantly and turn bright pink.
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In estrus, they’re walking sexual advertisements, and are then far more alluring. Because estrous periods are to some degree synchronized, there are times when a chimpanzee group is a sea of bobbing, compliant, soliciting swollen red rumps. Olfactory cues also signal their sexual availability. In marginal cases a passing male, unable to determine just by looking if she’s ovulating, may simply insert his finger into her vulva and take a sniff.

Chimpanzee sex isn’t a long and drawn-out business. Maybe eight or nine thrusts, each taking less than a second, and they’re done. The males have, by human standards, impressive recovery rates, including documented sequences of many ejaculations at five-minute intervals. Females in estrus are especially attractive in the early morning, probably because of the long and stressful celibacy imposed on the males by the necessity of having to sleep at night. As a kind of community property for the males, she may be taken every ten minutes by one male after another through mid-morning, by which time they may tire a little.

Occasionally a heroic or foolish female will refuse the male despite his transfixing stare, threatening gestures, and other signs of arousal. When he makes his approach she may scream and run away from him. Generally she doesn’t get far. When some hesitation is discerned, young males will ostentatiously search for a rock, or actually find one and make as if to throw it at her. This serves almost always as a
convincing argument. One of the earliest studies of chimp sexual behavior suggested that female compliance occurs “by reason of the dominance or impulsiveness of the male and the desire of the female to avoid risk of physical injury by obeying his command.”
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Despite their apparently unrestrained sexual behavior, chimps get jealous. A male who rejected the solicitation of a female in estrus, but instead copulated with her daughter, was slapped in the face by the outraged mother. Cruising migrant females from the next territory are threatened or attacked by the local females—especially if the visitors go so far as to groom with one of the resident males. The male may also blaze with sexual jealousy over a particular female’s behavior—but, almost without exception, only when she is vividly pink and swollen and able to conceive. High-ranking males will then chase away aroused lower-ranking males. Although it’s unlikely he’s thought this out, his motive, it seems very clear, is to monopolize her around the time of ovulation so that no one but he can father her children.
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As far as he’s concerned, the rest of the time she can do as she pleases.

Possessiveness is hard to maintain, though, at the core of the territory where the chimp population density is high. Even the most vigilant and high-ranking males will be distracted—by hunting, say, or challenges from lower ranks, or insufficient deference, or by grooming, or by the necessity of adjudicating disputes. And during such an intervention—it may last only a few minutes—other males, patiently awaiting their chance, pounce on the off-limits female, especially if she’s in estrus. Kleptogamy is on their minds. In zoos a female will, as soon as the alpha male is removed from her cage, present herself to lower-ranking males, even if this requires adroit positioning so the act can be performed through the bars of two adjacent cages. Both in the wild and in captivity, when the cuckolded male discovers what has happened, he attacks the female. Perhaps he knows that she was all too willing. Besides, it’s much safer than attacking a rival male.

Even when the alpha is present, a subordinate male may catch the eye of a female who strikes his fancy and then gaze pointedly toward
some nearby bushes. Nonchalantly, he then ambles off, often followed after a discreet interval by the female. Sometimes their infidelity is observed. Motivated by jealousy or by the wish to ingratiate himself to the leader, the informer rushes up to the alpha in great excitement, takes his arm, points, and leads him to the treacherous couple. At other times the female may inadvertently reveal what is going on by uttering a high-pitched scream at the moment of her orgasm. After being discovered in this way more than once, females do not usually abandon the risky practice of clandestine rendezvous; instead, they learn to suppress the scream, converting it into a kind of husky pant.

Frans de Waal reports that, following a long grooming session between a high-ranking and a low-ranking male,

To achieve reliable sexual monopoly during her estrus, the ardent male must usher the female away from the multitude. Scientists who study chimps call this “consortship,” and distinguish it from “courtship.” The proposition is put to the female as follows: He takes a few steps away and looks at her over his shoulder. If she does not instantly follow, he shakes a nearby branch. If this provides insufficient inducement, he will chase her and, if need be, attack her. More often she goes quietly, especially if he’s high-ranking. Then, off somewhere alone in the forest, he has her to himself. It is a distant intimation of monogamy.

Consortship typically lasts for weeks, and is not without its perils. The happy couple may be attacked by predators or patrols from the neighboring territory; and the male’s status in the dominance hierarchy may be undergoing active review during his absence. Jane Coodall reports a few cases in which the young female’s mother invites herself along on the consortship; “as far as the male is concerned,” she is a “most unwelcome chaperone.” Here, where conception is most likely, the incest taboo is particularly vivid—no
case is known of a male chimp ever inviting his own mother or sister to be his consort.

Why do the females put up with all this? Certainly males are larger and stronger than females and can and will hurt them, if that’s what’s needed to get their way. But this is only in one-on-one interactions. Why don’t females band together to defend themselves against a sexually predatory male? If two or three aren’t enough, six or eight would be. This is known, but rare, in the wild. (It is the custom among the chimps in the Tai National Forest in the Ivory Coast.) But it’s more common when they’re in closer quarters, as in the Arnhem colony in the Netherlands. Here the social conventions are different. If a male solicits a female and she’s uninterested, she so indicates, and that, usually, is that. If he makes himself obnoxious, he may be attacked by one or more other females. It is astonishing that so striking a characteristic of chimpanzee life in the wild as male sexual oppression of females can to such an extent be reversed merely because they’re all crowded together in a minimum security prison. We’ve already seen how, under these conditions, restraint, coalition building, and peacemaking by females come to the fore. Societies in which females have something approaching equality are also societies that benefit from their political skills.

In a state of freedom—where it’s possible to avoid your rivals by taking your sweetheart on a little trip into the country, and where you can escape a bully by running away—the circumspection required in crowded conditions is relaxed. Here testosterone is at full throttle and gentlemanly behavior is uncommon. The primate expert Sarah Blaffer Hrdy
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speculates that, among wild chimpanzees, female compliance to male sexual demands is the single mother’s desperate strategy for safeguarding her children. The males, Hrdy proposes, nursing their resentment at any rejection, might attack the children of an unresponsive mother (perhaps at a later time), or at least not protect them against attack by others.
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In the brutal world of the chimpanzee, she suggests, the female does what the males ask in order to bribe
them, so they will not kill (and, who knows, if they’re in a good mood might even help save) her children.
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If Hrdy is right, perhaps the males are not oblivious of the bargain struck. Do they threaten the children
in order
to make the mothers come around? Do they attack children at random as a cautionary lesson for any mothers toying with noncompliance? Have chimp males organized a protection racket, with the females and the young as their victims?

Let’s leave aside the possibility of conscious extortion, and think for just another moment about Hrdy’s speculation. The females don’t provide food for the males. They don’t seem to be any better at grooming than the males. Perhaps the only commodity—certainly the most valuable commodity—they can offer to protect their children is their bodies. So they make the best of a desperate situation. Now a male is less likely to attack and more likely to protect her baby. But when circumstances change, when aggression is inhibited because of crowding, the females can finally say “No”—without having their heads handed to them for it.

Again, we must not imagine that chimps think all this through. They must have some other, more immediate reinforcement of their behavior. Hrdy raises the question of the selective advantage of orgasms, especially multiple orgasms, among female apes and humans. In a monogamous couple, what evolutionary benefit does it confer? she asks, and argues that none is apparent. But if instead we imagine the female copulating with many males in order that none of them harm her offspring, then, Hrdy conjectures, the orgasm—reinforcing successive matings with many partners—plays a vital role.

To what extent female sexual compliance is coerced by the males and to what extent it is entered into voluntarily and exuberantly is still not clear.

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Nucleic acids compete, individual organisms compete, social groups compete, perhaps species compete. But there is also competition on a very different level: Sperm cells compete. In a single human ejaculation there are some 200 million sperm cells, the fittest among them with tails lashing, racing against each other, speeding along at an average clip of five inches per hour, each striving—or so it seems—to be first to reach the egg. A surprising number, though, from normal, fertile males have deformed heads, multiple heads or tails, kinked tails, or are just motionless, dead in the water. Some swim straight, others in convoluted paths that may turn back on themselves. The egg may actually choose among sperm cells. Chemically, it cries out to them, egging them on. Sperm cells are equipped with a sophisticated array of odor receptors, some oddly similar to those in the human nose. When the sperms obediently arrive in the vicinity of the calling egg, they don’t seem to have sense enough to stop swimming and thrashing, and molecules on the eggs surface may cast out a kind of fishing line, hook the sperm, and reel it in. The fertilized egg then promptly establishes a barrier that turns away all future sperm cells who may come blundering in. These modern findings are rather different from the conventional view of the passive egg waiting to be claimed by the champion sperm.
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But there is, in an ordinary impregnation, something like one success and 200 million failures. So conception, while controlled to a significant degree by the egg, is still in part the result of a competition among sperm cells for speed, range, trajectory, and target recognition, at least.
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