Chapter 3 Chapter Two Sex
Sexually, the naked ape of today finds itself in a difficult situation.As a primate he is drawn in one direction; as a carnivore he is drawn in another; as a member of a highly developed civilization he is drawn in another.
First, his basic sexual qualities can all be traced back to his ancestors, the fruit-eating, forest-dwelling apes.In order to adapt to hunting life on the wilderness, these basic characteristics have undergone drastic revisions.This process of change is difficult enough.In turn, however, these revised characteristics had to be further adjusted to accommodate the rapid development of social structures, which became increasingly complex and culturally conditioned.
The first stage of change, from the sexual behavior of fruit-living arboreal apes to that of hunting apes, took a long time to achieve, but the transition was quite successful.However, the second-stage changes were not as successful as the first-stage changes.This time the transition was extremely rapid and relied on intelligence and learned self-control rather than on biological change based on natural selection.It can be said that instead of saying that the progress of civilization has shaped human sexual behavior, it is better to say that human sexual behavior has shaped civilization.If this assertion seems oversimplified, let me state the argument first.At the end of this chapter, we will go back and examine this assertion.
First, we must find out exactly what naked apes are doing sexually today.This step in the research sounds easier than it is, because sexual behavior varies widely, and sexual behavior can vary from society to society, as well as within the same society.The only way to do this is to accept the generality of the findings, which have been drawn from a large sample of the societies most productive in the progress of civilization.Small, backward, underdeveloped societies are negligible.There may be many fascinating and eccentric customs in these societies, but biologically speaking, these sexual behaviors no longer represent the mainstream mode of evolution.In fact, these societies may have been less successful in the evolution of their biological identities precisely because their deviant sexual behavior did not help.
Most of the materials used in this book are taken from several research reports conducted in North America in recent years. These studies have taken a lot of effort and mainly focus on North American culture.Fortunately, biologically speaking, North American cultures were large and accomplished enough to represent modern naked apes without fear of distorting the picture.
Sexuality in our species goes through three typical stages: mating formation, presexual activity, and the act of coitus, usually in this order, but not always.The period of mating formation, usually called the courtship period, is astonishingly long by animal standards.The courtship period usually lasts for several weeks, or even as long as several months.As in other species, the courtship period is characterized by tentative and ambivalent behaviour, a mixture of fear, daring approach and sexual attraction.If the sexual temptation signals of both parties reach a certain intensity, the nervousness, fear and indecision will gradually decrease.So-called seductive signals include facial expressions, body gestures and courtship words.Courtship speech includes both very specific, highly symbolic verbal signals and equally important, uniquely sweet accents.It is often said that courting lovers "talk softly."This idiom sums it up; tone of voice in courtship is more important than words themselves.
The first stage of sexual inducement is manifested by visual and audible images, followed by physical contact between the courting partners.Often accompanied by twisting of the body.After the mate is formed, there is a marked increase in body twisting.First rubbing with hands, hugging each other with arms, followed by kissing on the face, mouth to mouth.The two naturally embraced tightly, or hugged each other quietly, or hugged and caressed each other.It is often seen that lovers suddenly separate and chase each other, play and dance, and the playful pattern of childhood may be manifested again.
Most of the behavior in the courtship phase is carried out in public.Once you enter the stage of pre-sexual behavior, you must pursue privacy, and the subsequent behavior should not be seen by others as much as possible.After entering this stage, the behavior pattern of lying down increases significantly.The physical contact is stronger and the hug lasts longer.Side-by-side supines, which are less emotionally intense, often give way to passionate face-to-face hugs and intimacy.This cuddling position may last for a few minutes, or it may last for hours.At this time, verbal and visual signals are not as important as in the first stage, and physical contact signals become more frequent.
The above sexual stimuli are the stimuli given to partners of the opposite sex during the eruption period of pre-sexual activity, thus causing physiological sexual impulses and leading to sexual intercourse.
The coitus phase is shorter than the sexual preparation phase, which is typical of the coitus phase.In most cases, men reach orgasm within minutes unless something is done to delay the process.Other primate females do not appear to have orgasms, but naked ape females have this uncanny pleasure unique to them.
After orgasm, both partners are generally exhausted and usually need to relax, rest, and often fall asleep peacefully.
Now that we've talked about sexual stimulation, let's talk about sexual response.How does the human body respond to the above various strong sexual stimuli?The pulse, blood pressure and respiration of both men and women increased significantly.These changes begin during the pre-sexual preparation phase and are most pronounced during orgasm.The normal pulse rate is 70-80 beats per minute, 90-100 beats at the beginning of sexual impulse, 130 beats when sexual impulse is strong, and 150 beats during orgasm.Blood pressure went from 120 to 200, even to 250.The breathing deepened with the impulse, and when it reached the climax, it was gasping, accompanied by rhythmic moaning.At orgasm, the facial muscles may spasm, the lips part, and the nose flaps, similar to the response of an athlete during strenuous exercise and comparable to that of a person with dyspnea.
There is also a dramatic change during sexual arousal. The distribution of blood flow is greatly shifted, from the internal organs to the body surface.The increased blood flow to the skin had several significant effects.It not only raises the temperature of the body surface, and this change can be felt when the two parties touch each other-this is called sexual burning, or so-called lust; but there are also obvious changes in certain areas of the body surface.When the urge is strong, there will be a typical sexual flush.Sexual flushing is most common in women, starting in the upper abdomen and spreading to the upper breasts, upper chest, sides and center of the breasts, and finally to the lower breasts.Blush may also appear on the face and neck.In women who react strongly, sexual flushing may also spread to the lower abdomen and shoulders.Elbows, to thighs, arms and back when high.In some women, the blush can cover almost the entire body surface.It has been described by some as a measles-like erythema, which itself appears to be a sign of sexual irritation.Men also experience a flush on the skin, although this is not as common as in women.Like a woman's blush, a man's blush begins in the midsection and progresses to the chest, neck, and face.Occasionally, it also affects the shoulders, forearms and thighs.After orgasm is achieved, the flush dissipates rapidly, in the reverse order of appearance.
In addition to sexual flushing and superficial vasodilation, several dilatable organs exhibit marked vasodilation.The blood is concentrated in these organs because more blood is input by the arteries and less blood is taken away by the veins.The phenomenon of organ enlargement can last for a long time, because the enlarged arterial blood vessels then compress the return flow of venous blood vessels.Dilated blood vessels occur on the lips, nose, earlobes, nipples, and genitals.Women's breasts will also enlarge.Congested lips become larger, redder, and more prominent.Nostrils enlarged, nostrils dilated.The earlobe becomes thick and swollen.The nipples of both men and women are swollen and firm, especially the changes of women's nipples are obvious (not only because of the expansion of blood vessels, but also because of the contraction of the muscles of the nipples).A woman's nipple can be raised by one centimeter and half a centimeter in diameter.The areola area is also enlarged and darker in color, a change not seen in men.Women's breasts also become significantly larger, and can expand by about 25% by the time of orgasm. They are firmer, more rounded, and taller than usual.
The genitals of both sexes undergo considerable changes as the drive grows.Once the orgasm is reached, all changes quickly subside and the body returns to its original state.During the rest period after sexual intercourse, the human body quickly returns to its usual quiet physiological state.
The above outlines the sexual stimuli and responses of our species.On this basis, we can explore what sexuality meant in the lives of our ancestors, and what it means in our own.First, however, it is worth pointing out that the frequency of the aforementioned sexual stimuli and sexual responses is not consistent.Some changes are inevitable when men and women have sex, and some only appear in some people.Even so, they occur frequently enough to be considered a "species trait".The following figures are given for the frequency of sexual responses. 75% of women have sexual blush, 25% of men have sexual blush.Firm nipples are a common phenomenon in women, but only 60% of men.Post-orgasmic sweating was a trait found in 33 percent of both men and women.In addition to the above-mentioned reactions, other bodily reactions are common features; of course, their intensity and duration will vary somewhat in different situations.
Another point that needs to be clarified is; the distribution of sexual activity over a person's life.Neither sex can have real sex until the age of 10.A large number of so-called "sexual games" can be seen in childhood.But until ovulation in women and semen in men, no functional sexual behavior patterns can emerge.Some women begin menstrual cramps at the age of 10; 80% of girls have normal menstruation by the age of 14. All 19-year-old women had menstruation.At the same time, the pubic hair grows, the buttocks become fatter, and the breasts bulge.In fact, the above changes are slightly earlier than menstrual cramps.The overall development of the body progresses slowly and is not completed until the age of 22.
Generally speaking, boys do not ejaculate for the first time until they are 11 years old, and their sexual initiation is later than that of girls. (The earliest record of ejaculation in boys is 8 years old, which is extremely rare.) By the age of 12, 25% of boys have ejaculated; among 14-year-old boys, 80% have ejaculated for the first time. (By now they've caught up with teenage girls' menstrual experiences.) The average age at which boys ejaculate for the first time is 13 years and 10 months.As in the case of girls, boys also develop typical secondary sexual characteristics.Body hair begins to grow, especially pubic hair and beard.The typical sequence of body hair growth is: pubic area, underarms, lower lip, cheeks, chin, before slowly spreading to the chest and other areas.A man's buttocks will not be fat; on the contrary, his shoulders will be widened.The voice becomes thicker and lower.Voice changes are also present in girls, but to a much lesser degree than in boys.The genitals of both sexes accelerate growth and development during this time.
Interestingly, if sexual responsiveness is measured by the frequency of orgasms, men reach their peak at a much younger age than women.Although the age of male sexual maturity is one or two years younger than that of females, males can reach the peak of sexual desire when they are in their teens; females have to wait until their twenties or even their thirties to reach the peak of sexual desire.In fact, it takes until 29 for a woman to match the sex drive of a 15-year-old man. 15-year-old girls, only 23% of people have the experience of orgasm.This percentage is only 53% for women of other ages. The percentage among 35-year-old women is 90%.
An adult man's orgasm is about three times a week.The frequency of orgasm in general men reaches its peak between the ages of 15-30, and then declines steadily until old age.
The phenomenon of gradual decline of sexual desire with age increases, and there is a similar situation in women.For all women, when ovulation ends suddenly around the age of 50, the ability of sexual response does not decline significantly.However, the effects of menopause on sexual behavior vary widely among individual women.
Most of the above-mentioned sexual intercourse activities are carried out between fixed spouses.This kind of sexual spouse relationship may be a formally recognized husband and wife, or it may be an informal ambiguous relationship.The higher frequency of sex in non-marital relationships cannot be considered casual promiscuity.For the most part, it also necessarily goes through the stages of courtship and mate formation, even if the resulting mate bond does not last particularly long.In some cases, formal spousal relationships were broken down and eventually dissolved (in the United States, for example, the divorce rate was 0.9 percent in 1956).The mating mechanism of our species, while a very powerful bond, is far from perfect.
With the above facts before us, we can turn to the following question: How does the way we behave sexually contribute to survival?Why do we behave this way and not another way.If we switch to another question, it may be more helpful for us to answer the above two questions.The question is: How does our sexual behavior compare with that of other living primates?
We can immediately see that humans are much more sexually active than any other primate, including our closest relatives.For them, there is no long courtship phase.Few species of monkeys form lasting pair bonds with apes.The pattern of the pre-sexual phase is relatively simple, usually only a few simple facial expressions and calls.Mating itself is also very brief. (Taking baboons as an example, the time from copulation to ejaculation is only seven or eight seconds, and the number of male pelvic slides is at most 15 times, and often less than 15 times.) The female does not seem to have any sexual orgasm.Even if there is, compared with human females, it is just a negligible sexual response.
The estrous period in female monkeys and apes is very restricted.Generally speaking, there is only about one week in a month, or a little more than a week.Even this short estrous period is a big step forward compared with lower mammals.The estrous period of lower mammals is more limited by the ovulation period.In our species, the sexually active period of the female is pushed to the extreme in the general tendency of primate estrus to be prolonged; in fact, it is not limited by any time.Once the female monkey is pregnant and enters the lactation period, she stops having sex.In contrast, human sexual life extends into pregnancy and lactation, and is only severely restricted during the brief period before and after childbirth.
Apparently, the naked ape is the most sexually driven primate species in existence.To get to the bottom of it, we have to go back to his origins.What happened to the evolution of the naked ape?First, he has to hunt to survive.Second, he must have a brain that is better than other animals to compensate for his body that is not suitable for hunting life.Third, he must have a longer childhood to make his brain more developed and smarter.Fourth, when the men went hunting, the women had to stay in the residence to take care of their children.Fifth, men must cooperate when hunting.Sixth, they must walk upright and use weapons with their upper limbs to ensure successful hunting.I do not intend to say that the above-mentioned changes occurred in this order.On the contrary, they undoubtedly took place gradually and simultaneously, with each change simultaneously promoting the others.I'm just listing six basic major changes in the evolution of hunting apes.I believe that the various elements that make up our complex sexuality today are inherent in the 6 variations above.
First of all, when a man leaves a woman to go hunting, he must ensure the fidelity of the woman.Therefore, a woman has to form a spouse relationship with a man.At the same time, give lesser males more sexual rights if they are to be expected to cooperate in the hunt.Women should let more men share, and the sexual organization model should be more democratic and less tyrannical.On the other hand, every man also needs to have strong mate tendencies.Moreover, men are now armed with deadly weapons, and the dangers of sexual combat are greatly increased--another reason why men are content to marry only one woman.A final reason: the slow development of infants and young children, which greatly increases the responsibility of parents.Parenting behaviors must be developed, and parental responsibilities must be shared by both parents—another reason for a strong spousal bond.
With this situation as a starting point, it is possible to see other things derived from it.To form a mate bond, naked apes must develop the capacity to fall in love, and must keep a constant sexual partner in mind.No matter how he expresses this meaning, there is only one conclusion: how did he learn to fix his spouse?What factors contributed to his formation of a conjugal relationship?As primates, naked apes have long had a tendency to form short-lived mates, ranging from a few hours to a few days.But this relationship must be strengthened and extended.One factor contributing to this development is the naked ape's own extended childhood.During the long growth period, he formed a deep attachment with his parents.The intensity and persistence of this attachment greatly exceeds the attachment of monkeys to their parents.As the naked ape matured and became self-reliant, he lost the bond of attachment to his parents, creating a "relational vacuum" that had to be filled.So, he is ready to replace his parental bond with a new one that is equally strong.
Even if this void is enough to reinforce his need to form a mate, he needs something else to help maintain the mate.The conjugal bond is long enough to accommodate the long years of parenting.After falling in love, you must maintain love.A long and passionate courtship guarantees the formation of love, but thereafter something new is needed to maintain it.The most simple, natural and straightforward way is to make the joint activities of the spouses more complex and more rewarding.In other words, it is to make sex life more sexually passionate.
How is this evolutionary feature achieved?The answer seems to be: by all means.If we look back at the behavior of naked apes today, we can see how this pattern emerged.The increase in female sexual activity cannot simply be explained by an increase in birth rates.It is true that women who remain sexually active during their childbearing years do increase birth rates.Since children depend on their parents for a long time, it must be a disaster if a woman cannot accept sex during her child-rearing period.However, this cannot be used to explain her frequent menstrual cycle
The physiological phenomenon of keeping libido open.There is only one ovulation per menstrual period, so sexual intercourse in non-ovulatory periods has no reproductive function at all.The sexual life of human beings obviously has nothing to do with the reproduction of offspring; the focus of its attention is to strengthen the conjugal relationship through the mutual reward of sexual partners.From this point of view, the repeated culmination of conjugal sexual life is obviously not a product of the highly sophisticated and corrupt modern civilization, but a deep-rooted, biologically based, healthy trend that meets the requirements of evolution.
During menopause, that is to say, during pregnancy, women can still accept sexual demands from men.This is especially important because disappointing a man for a long time after a one-on-one relationship is formed can jeopardize the relationship.It can jeopardize the spousal relationship.
The amount of time spent in sex has increased, and in addition to that, the sex life itself has become more elaborate and complex.The life of a hunting ape leaves us with shaved body hair, bare skin, and more sensitive palms, two factors that greatly expand the range of sexual stimulation in face-to-face physical contact.In the pre-sexual preparation stage, the stimulation of physical contact plays an important role, and the actions of caressing, caressing, clinging, and hugging occur repeatedly, far exceeding those of any other primate.In addition, specialized sex organs such as the lips, earlobes, nipples, breasts, and genitals are filled with sensitive nerve endings that are highly sensitive to stimulation from physical contact.The earlobe appears to be a specialized organ that evolved for this purpose.Anatomists often refer to the earlobe as a meaningless epiphysis, a "useless fatty growth".Generally, earlobes are interpreted as an evolutionary 'relic' of large ears. However, if we look at other primates, we see that their ears are not very large. It seems that instead of being a relic of evolution, the earlobes are are new to evolution. We found that the earlobes are engorged and hypersensitive during the onset of sexual arousal. Thus, they are undoubtedly another sexually sensitive area created by evolution. (Oddly enough, this function has been fairly neglected; however, it is worth noting that some people have been documented to be sexually aroused by stroking their earlobes.) Interestingly, the protruding and fat nose of humans is another unique and mysterious feature, anatomical Scientists have yet to give an explanation. One anatomist said it was "purely a well-developed variation with no functional significance." It is hard to imagine that such a definite and unique neoplasm would have no evolution in primates. Significance. When you know that when you are sexually aroused, the cavernous tissue around the nasal cavity will erect, causing the nostrils to expand and the alar of the nose to flush blood, you will doubt the above statement.
In addition to the aforementioned sexual stimuli in physical contact, there are some rather unique visual cues.Complex facial expressions play an important role here, although they evolved to improve other aspects of communication as well.Our species has the most complex and well-developed facial muscles of all primates
Meat expression.In fact, our facial expression system is the most delicate and complex of all living animals.With the help of subtle movements of the muscles around the lips, nose, eyes, eyebrows, of the forehead muscles, and various combinations of facial muscle movements, we can express all kinds of complex emotional changes.Facial expression is extremely important in sexual activity, especially in the early stages of courtship. (Forms of facial emotional change are discussed in another chapter.) Faces enlarge during sexual arousal; although the change is subtle, we are often unaware of how sensitive we are to it.The shine on the surface of the eyeball is another visual signal.
Like the fat earlobes and protruding noses, so are human lips
an evolutionary trait.This feature is not seen in other primates.Of course all primates have lips, but their lips do not roll outward like ours.Chimpanzees can turn their lips out when they deliberately pout, exposing mucous membranes that normally hide in the mouth.But the time it turned its lips was very short, and after a while its lips returned to their original thinness.Instead, our mouths are perpetually turned outward.For chimpanzees, the human mouth is always pouted.If you get a chance to give a chimpanzee a cuddle, he'll probably give you a kiss on the neck, and by then you'll have no doubts about his ability to give a signal with his lips.For chimpanzees, kissing is not a signal of sexual stimulation, but a signal of greeting.But in humans, kissing is used both for intimacy and for greeting.Kissing is especially frequent and persistent during the run-up to coitus.This evolution presumably made it easier to permanently expose the sensitive mucous membranes of the lips, so that during prolonged kissing, the surrounding muscles of the lips do not need to contract to ensure the mucous membranes of the lips are in contact.However, its capabilities are not limited to this.The exposed mucous membranes give the mouth skin a well-defined, distinctive shape.The rosy profile of the lips does not fade and dissolve into the surrounding skin, it maintains a fixed demarcation.So the lips have also become an important visual signal device.Sexual arousal causes sweating of the upper lip, reddening of the mouth and congested skin.The sharp lines of the lips obviously help make these finer changes in sex signals more noticeable.Of course, even in the absence of sexual arousal, a person's lips are redder than the surrounding skin.Such lips themselves, even when they do not reveal sexual arousal, become a sex-peddling advertisement, calling the attention of the opposite sex to the existence of this sexual construct for kissing.
Anatomists, who do not understand our unique mucous everted lips, say this evolutionary feature is "not fully understood" and suggest that it may have something to do with the increased length of time babies suckle.But a chimpanzee baby is also good at suckling, and its lips are more muscular and more absorbent, making them seem better suited for sucking.Moreover, the reason for suckling cannot be used to explain the evolutionary characteristics of sharp lips.Nor can it be used to explain differences in lip shape among people with different skin tones.Instead, these differences are easier to understand if you think of the lips as a device for sending visual signals.If the climate requires a darker skin tone, it will reduce the color difference between the lips and the surrounding skin, thereby affecting the ability of the lips to send signals.If the lips are really an important signaling device, we can expect a compensation to emerge; actual evolution seems to be the case.The negro's lips are thickened and more prominent, and thus retain their striking character.What they lose in color difference, they are compensated for in thickness and shape.Moreover, the lines on the edge of black lips are more distinct.People with lighter skin have more raised lips and are slightly lighter than the surrounding skin.From the perspective of anatomical features, the lip shape of blacks does not seem to be a very primitive feature, but a relatively positive special change trend in lip evolution.
There are many other obvious visual cues of sexual stimulation.As mentioned earlier, the symbol of the arrival of puberty's reproductive ability is the growth of striking body hair, especially pubic and armpit hair, and male beard growth.A woman's breasts develop rapidly.Body shape also changes, with broadened shoulders in men and enlarged pelvis in women.These changes not only distinguish sexually mature individuals from immature individuals, but also separate mature males from mature females.They are not only a signal that the sexual system is in operation, but also indicate the sex of each individual.
Enlarged breasts in women are generally seen as an evolution primarily due to the need for breastfeeding, rather than a change in the needs of sexual life.There seems to be no evidence for this idea.Other primates have plenty of milk to feed their offspring, but they don't develop the well-defined hemispherical breasts.Only human females have such unique high breasts.Evolution has resulted in high, domed breasts that appear to be another example of sexual signaling.Bare skin made this evolution possible, and it also drove the evolution of breasts.Enlarged breasts are not very noticeable hidden under body hair, but after the body hair falls off, they stand out clearly.In addition to being conspicuous in appearance, they also draw attention to the nipple, making it more noticeable when the nipple is erect during sexual arousal.The areola around the nipple darkens during sexual arousal, which also makes the nipple more attractive.
Exposed skin also makes possible the sign of sexual flushing.Sexual flushing occurs in limited nudity in other animals, but in humans sexual flushing extends over a much wider range.Facial flushing occurs especially early in courtship, and typical mottled flushing is common in the later stages of sexual arousal. (This form of sexual signaling darker-skinned people have to sacrifice for acclimatization. But we know they also have sexual flushing, because although the change is not visible to the naked eye, a closer look reveals the radiance of the skin showing major changes.)
Before we leave this series of visual sexual signals, we must examine an unusual aspect of their evolution.For this purpose, we'll turn to our lowest primate distant relatives, the monkeys, for some curious changes.Recent studies by German scholars have shown that some species have begun the process of self-imitation.The most dramatic examples are the West African and Ethiopian baboons.The male West African baboon has a blood-red penis and a bluish blotch on either side of the scrotum.The same color pattern appears on the face, with a blood-red nose and a dark blue denomination protrusion.It seems that its face mimics its genitals, showing the same sexuality.When a West African male baboon walks toward another baboon, the stark contrast in genital coloration is concealed by the way he walks, but he can still send an important message with the help of a face that mimics genital color.Ethiopian female baboons are also enthusiastic about self-imitation.She has a dark red area around her perineum, surrounded by white papillae.The labia in the middle of the perineum are blood red.This visual pattern was repeated on her breasts: a bare blood-red area surrounded by the same white papillae.The nipples in the middle of this red skin were dark red, and the two nipples were close together, giving a strong impression of their close resemblance to the labia.
(In fact, the nipples are so close together that the baby baboon sucks both nipples in his mouth at the same time.) The redness of her breasts, like that of her perineum, changes with her period.
We cannot avoid the conclusion that the West African and Ethiopian baboons somehow transplanted the genital signals to the front of the body.We know too little about wild West African baboons to guess why this strange change occurred in this species.However, we do know that wild Ethiopian baboons use a sitting position more often than similar monkeys.If the sitting posture is their more typical posture, it is natural to say that by moving the sexual characteristics to the chest, it will be easier for them to transmit these signals to their own kind; Information is not so easy.Many primates have brightly colored genitals, but the evolution of the body front to mimic the color of the perineum is rare.
Our species has undergone drastic changes in body posture.Like Ethiopian baboons, we spend a lot of time in a sitting position.We also maintain an upright face-to-face approach in socializing.Does it follow from this that we like the same mode of self-imitation?Does our sitting and upright posture also affect our sexuality?From this point of view, the answer seems to be yes.In all primate mating positions except humans, the male approaches the female from the buttocks.The female pulls her hips up and sends it to the male.After the male sees it, he moves closer to the female and mates with the female from behind.During copulation, the fronts of the bodies do not touch, and the male's genitals press against the female's buttocks.The situation with human sexual intercourse is very different.It is not only the face-to-face long-term intimacy in the preparation stage before sex, but also the main position in the sexual intercourse itself.
Besides the all-important visual stimuli, some olfactory stimuli also function as sexual stimuli.Our sense of smell has been greatly reduced in evolution, but it is still quite effective, and the role of smell in sexual behavior is more than we are usually aware of.We know that men and women smell differently; it has been pointed out that part of the process of forming a mate—courtship and falling in love—involves imprinting the other's smell, becoming attached to a particular scent of the lover's body.Related to this, there is another interesting discovery: the smells that adolescent boys and girls like will change.The previous preference for sweet and fruity aromas gradually weakens at sexual maturity, and then changes dramatically, and adolescents at this time fall in love with floral, oily and musky scents.This change occurs in both sexes, but men respond more strongly to scents than women.It is said that even if there is only 1/8 million musk in the air, men can smell it.Interestingly, musky scent dominates the odor signaling systems of many mammals and is produced in specialized glands.Although we have large, dedicated scent glands, we have many smaller glands called eccrine glands.The secretions of the eccrine glands contain many solid substances.The apocrine glands are found in several places throughout the body, but are concentrated in the underarms and genitals.The hair in these areas undoubtedly plays a role in absorbing qi.It is said that the odor produced by the eccrine glands increases during sexual arousal, but no detailed analysis data has been published so far.However, we have established that women have 75% more eccrine glands than men.Interestingly, if we recall the mating situation of lower mammals, we will find that the male sniffs the female more, and the female sniffs the male less.
The distribution of eccrine glands in the human body seems to be a change to adapt to face-to-face sexual intercourse.There is nothing unusual about the eccrine glands in the genitals, and in this we are like many mammals.However, the concentration of eccrine glands in the axilla is a more unexpected feature.It appears to be related to the general tendency of the human body to focus sexual stimulation on the front of the body, in relation to face-to-face sexual encounters.In terms of smell, it makes the nose of the sexual partner very close to the main olfactory area of the armpit, and it is easy to smell the other party's scent during the pre-sexual preparation stage and the sexual intercourse stage.
迄今为止，我们探讨的是，人类在改善和拓展品尝性性行为中的各种方式；这方面的各种进化特征是为了不断强化配偶性行为的报偿功能，以巩固和维持配偶关系。但是品尝性行为产生了性满足的高潮，所以性高潮的进化机制也需要改善。请你停下来想一想灵长目动物古老的性行为系统。雄性灵长目任何时候都处于性活跃的状态——除了刚交尾之后的短暂时间之外，性高潮对雄性非常重要，因为性紧张的解除降低了它们的性冲动，使它们能再生足够的精子。相反，雌性的发情期却很受局限——只集中在排卵期前后很短的时间里。发情期的雌性任何时候都愿意与雄性交偶。交配次数越多，成功受精的保证就越大。对雌性来说，不存在什么性满足，不存在性高潮，其性冲动是无法平息无法遏制的。它们的发情期太短，不能浪费一点时间，要不惜一切代价完成受精的任务。如果有性满足的高潮，它们就浪费了宝贵的交尾期。雌猴在交尾结束，当雄性从它身上爬下来时，没有一点情绪激动的征兆，它常常平平静静地走开，显出一副若无其事的样子。
对于我们这个配偶固定的物种来说，情况就迥然不同了。首先，因为只有一位配偶，当男子性交后精力耗尽时，女子仍然希望响应男子的性要求，就没有什么特别的好处了。所以，女子出现性高潮的快感就不会遭遇什么阻遇的机制。相反，有两点非常有利于女子性高潮的形成。第一点是从与配偶的性合作中所得到的极大的报偿；正如其它改善性行为的进化一样，女子的性高潮能强化配偶关系，起到维系家庭的作用。第二点是它能增加受精的机会。如果要弄懂这一点，我们又必须回头看一看我们的灵长目近亲。雌猴交配之后，她可以若无其事地立即开始游荡，而不必担心精液流失，因为精液储留在它阴道里最深的部位。当它四肢着地行走时，其阴道走向仍然与地面基本平行。但是，倘若我们人类的女子对性交无动于衷，她也立即起身走路，情况就完全不同了。因为她直立行走，行走时阴道几乎与地面垂直。在简单的地心引力作用下，精液会顺着阴道往下流，因而会丧失很大一部分。所以，性交结束后，任何促使女性保持身体平行的生理反应都是非常有利的反应。女子性高潮时的强烈反应，能使她因满足而感到疲倦。这正是女子性高潮的效果，它具有双重的价值。
在灵长目动物中，人类女子的性高潮是独一无二的进化特征，从生理上说，它与男子的性高潮模式几乎是完全同一的，二者加起来表明，女子的性高潮从进化上说是一种“假性男性”反应。从两性的解剖生理上看，双方都具有异性潜在的解剖生理特征。从比较动物学的实践来看，一我们知道，进化可以使潜在的异性特征突现出来（即所谓“性别差错”的现象）。在这一点上，我们知道女子对阴蒂的刺激非常敏感。只要记住女子的阴蒂相当于男子的阴茎，那么事实的确表明：无论如何从起源上讲，女子的性高潮乃是从男子“借用”的一个模式。
所以我们可以归纳说。在改善品尝性性行为和性高潮行为的适应机制方面，各种进化特征都是为了增强裸猿的性生活，以保证配偶关系的形成，这一基本的特征不见于其它的哺乳类动物。但是，引进这一新趋势的困难尚未完全克服。我们看看当今裸猿的配偶，发现他们协调一致、互相扶助着养育婴儿，似乎万事无虞了吧；但是，婴儿长大，报快将进入青春期。到了那时又该怎么办呢？倘若灵长目古老的行为模式不予修正，成年男性很快就要把年轻的男性赶出群体，以占有年轻的女性。她们就将与自己的母亲一样，成为群体传宗接代的家族成员。而且，如果年轻的男性被赶到社会的边缘，处于低下的境地一许多灵长目动物就是这样的，那么，全部由男子组成的狩猎队中的合作精神就会受到影响。
显然，还需要进一步修改繁衍后代的体系，即需要一种外婚制。为了维持配偶制度，必须要让子女能找到自己的配偶，这个要求对实行配偶制的物种来说并非异常之举，许多低级哺乳类中也能看到这一制度。但是大多数灵长目动物都是社会化的助物，其社会性增加了外婚制的困难。大多数有配偶关系的动物中，后代长大之后，家族就分裂开来各奔前程。由于裸猿的社会合作精神，他不能采纳这种分散的办法。所以外婚制这个问题就成了一个摆在家门口的问题，不过其解决办法基本上是普遍一致的。正如所有实行配偶制的动物一样，父母彼此有强烈的占有欲望。母亲在性生活上“占有”父亲，反之亦然。一旦子女开始出现性征，他们就成为父母的性对手，儿子是父亲的对手，女子是母亲的对手。父母有赶走子女的倾向。后代也需要建立以自己的家庭为基础的“领地”。他们之所以有这种要求，首先是因为父母建立了一个养育后代的家庭。他们只需复制父母安家的模式。父母的家庭基地，自然由父母支配，属父母所有，所以它的属性不适合于女建立的领地。父母家中以及生活于其间的成员身上，到处都充塞着父母的信号，包括基本的信号和联想的信号。青春期的子女自然要拒斥这些信号，着手去建立自己繁衍后代的基地。这是具有领土欲的食肉动物的典型特征，而不是灵长目动物的特征。这是另一种基本行为的变化，裸猿在进化过程必须完成这一变化。
外婚制常被人说成是为了防止乱伦的表现．这一说法也许是令人遗憾的。因为它的言下之意是：族外婚是比较晚近才出现的现象，是一种文化上的控制行为。其实它一定是很早之前某一个阶段中所发生的生物进化，否则人类现今典型的繁衍模式，是不可能从灵长目背景之中演化出来的。
另一个与此相关的特点，似乎是人类独有的特征：女子的处女膜保留至成年。低级哺乳类在泌尿生殖系统发展的胚胎期有处女膜，但是幼态持续机制使裸猿的处女膜保留下来了。这就意味着，女子的第一次性交会遭遇痛苦。既然进化千方百计使女子对性生活的反应非常适应，所以乍看之下，女子同时又具有一个对抗性生活的机制，这似乎又有点莫名其妙。不过，情况并不象乍看之下那样自相矛盾。处女膜使第一次性交困难，甚至使之痛苦，这就使人不至于轻易丢失童贞。显然，青春期有一段“广交异性朋友”的阶段以寻找合适的伙伴。青春期少年没有理由不实现完全的性交而半途而废。配偶关系形成之前，他们不承担任何义务，他们要广交异性朋友，直至找到合意的伴侣。但是，年轻的女子如果不形成配偶关系，就会发现自己怀孕以后而没有伴侣。
在此还必须说一说单偶制和多偶制。配偶关系在全人类的兴起，自然有利于单偶制的形成，但是它不会绝对要求采用单偶制。如果狂暴的狩猎生活使男子人数稀少，就会出现幸存的男子占有不只一位女子的趋势。这可以在增加繁殖率的同时，不造成“多余的”女子无法找到配偶的危险局面。如果配偶机制只适合单偶制，绝对排斥多偶制，那就使种属的繁衍失去效率。但是，多偶制的形成不会没有困难，因为女子对男子有强烈的占有欲，争风吃醋会带来危险。而且，维持大家庭的经济压力也不利于它的形成。程度不高的多偶制固然可以存在，但是它受到严重的局限。有趣的是，尽管一些规模较小的社会中仍然存在着多偶制，但是所有的大型社会（其人口占世界总人口的绝大多数）实行的是单偶制。即使在容许多偶制的社会中，实行多偶制的男子通常也不过只有一小部分。多偶制在所有大型文化中不复存在这一事实，是否就是其成效卓著的一个主要因素，这个问题饶有兴趣。总之可以说，无论那些默默无闻的、落后的部落社会还在实行什么婚配制度，人类主流社会的婚配特性仍然以极端的形式表现出来，这就是长期的单偶制。
由此可见，狩猎猿就是这样的大杂烩：他是性生活很多的、固定配偶的一种动物，有许多独一无二的特性；他既保存了灵长目祖先的特性，又在进化为肉食动物的过程中发生了大量的变化，所以他成为兼有二者特性的复杂的物种。在此基础上，我们还要给他加上第三种成分：现代文明单纯的树栖猿演变为合作的狩猎猿的过程中，脑容量增加了，容量增大的脑髓忙于椎动技术的进步。简陋的部落居所变成了庞大的城镇。石斧时代发展到了繁荣兴旺的太空时代。但是，这些熠熠生辉的表层变化对人类的生殖系统有何影响呢？看来这个影响是很小的。文明演进太快太迅猛，任何根本的生物进化都来不及发生。表面上看似乎是发生了变化，然而事实上这种变化不过是虚假的幻相。在现代城市生活的表象之下，人还是原来那个裸猿。只不过是各种名目发生了变化：“狩猎”现在读作“工作”，“猎场”现在读作“公务场所”，“居所”读作“住宅”，“配偶关系”读作“婚姻”，“性伙伴”读作“妻子”等等。前面提及的美国学者对当代性生活模式的研究说明，裸猿的解剖生理机制仍然在当代人的性生活中发挥充分的作用。人类史前特性的残留，再加上比较动物学对食肉兽和灵长目的研究，给我们构建了一幅图象，使我们看见裸猿在远古时期如何使用性机制如何组织性生活的情况。当代人性生活的资料似乎也呈现出大致相同的图景，如果我们抹去公共道德那一层深色的外壳的话。正如我在本章开宗明义所说的那样，人类作为动物的生物属性塑造了人类文明的社会结构；而不是相反，人类文明的社会结构决定了人类的生物属性。
然而，尽管人类基本的性行为体系仍然以相当原始的形式保留了下来（社区扩大的同时并没有出现性生活社区化的模式），但是许多细小的控制和局限推广开来了。之所以需要这些控制和局限，那是因为人在进化过程中出现了一系列繁复的解剖生理性征，结果使人的性反应更加强烈和敏感。但是，这些解剖生理特征是为小型的关系密切的部落生活设计的，而不是为大城市生活设计的。我们在大城市的生活中。常常和成千上万的陌生人摩肩接踵，陌生人给人以刺激，也容易受他人的刺激。这是个新情况，必须有对付这一新情况的机制。
事实上，文化限制的兴起一定更为悠远，早在社会生活中碰见陌生人之前就出现了。即使在简单的部落社会中，配偶双方在公开场合走动时，也必须减少身体发出的性刺激。如果说要增加性生活的报偿功能以维持配偶关系的话；那么，如果配偶分开时，也必须采取步骤抑制性行为，以避免刺激第三者。在其它有配偶关系和社群生活的动物中，对性行为的抑制主要靠攻击性的姿势来完成。在人类这样的有合作精神的物种身上，好斗性较少的办法更加受欢迎。在这个问题上，我们发达的大脑可以出来帮忙。显然，言语交际有重要作用（比如说“我的丈夫不喜欢这样的事情”），正如它在许多社会接触中发挥着重要作用一样。但是，我们还需要更多直接与此相关的措施。
最明显的措施是遮掩得并不严实的、尽人皆知的遮羞布。由于裸猿直立行走的姿势，他走向任何一位同类，都不可能不暴露生殖器。其它的灵长物四足行走，所以不会有这个问题。它们想暴露生殖器，必须要取一种特殊的姿势。而我们却面对着他人的生殖器，每一小时，每一天，无论我们做什么，都无法避免这一事实。由此可见，用衣物遮盖阴部必然是很早的文化现象。用衣服御寒，无疑是人类从适宜的气候中移居寒冷地区后才出现的文化现象。但是，这个阶段大概要相当晚才会出现。
由文化环境的变异，与性刺激抗衡的衣物也出现各种变异。有的时候，衣物发展到遮盖第二性征（比如象乳罩和唇罩）的地步，当然有些衣物也不一定进化到这一步。在一些极端的例子里，女子的生殖器不仅用衣物遮掩得严严实实，而且完全被封锁起来。最广为人知的是贞节带。这是一根金属打制的带子，把女子的阴部和肛门套在里面，带子上钻有小孔以供排便。类似的作法还有缝合处女的外生殖器，直至结婚方才拆开，也有用金属钩环封锁女子外阴的情况。晚近还有人记录了一个极端的例子，有一位男子每次与妻子同房之后，都用锁把妻子的阴唇锁起来。当然，这种预防女子失贞的作法是非常罕见的。但是，用衣物遮掩会阴这一不太极端的作法，现在几乎成了普天之下的共同现象。
另一种重要的文化现象是，性行为本身成为隐私。生殖器不光变成了需要隐藏的器官，而且性行为本身必须隐秘。今天，其隐秘性产生的结果之一是，人们把性行为和睡觉联系在一起。和过人睡觉成了和某人同房的同义语。所以人们的性生活虽然分散在一日之中，但是它主要还是集中在晚上。
我们已经看到，身体接触成了性行为的一个重要部分，因此日常生活中必须抑制身体的接触。在繁忙的社区生活中，一定要禁止和陌生人的身体接触。如果碰巧接触到陌生人的身体，我们就要立即道歉，接触到的部分越是敏感，道歉的诚意就越是强烈。快镜头放映街头小景或大楼里熙来攘往的行人能清楚说明，人们时刻遵守着异常复杂的、避免接触陌生人的策略。
与陌生人接触的限制，只有在极为拥挤的情况下才能解除，只有对特殊行业的人才会开禁（比如象理发师、裁缝和医生），因为他们的职业使他们“有权接触”顾客和病人的身体。与密友和亲属的身体接触所受的限制较少。他们的社会角色确定他们不是性伙伴，所以和他们的身体接触危险较少。尽管如此，招呼问候时的身体接触仍有固定的程式。握手礼有固定的程式，亲吻礼也有固定的程式（双方面颊相贴），使之与性伙伴嘴对嘴的接吻区别开来。
体态的某些方面失去了性刺激的特征。女子双腿叉开的姿势，需要竭力避免。女子坐下时把双腿紧贴在一起，或者把腿架起来。
如果无法避免张开嘴巴——这个姿势有点象性反应的的口型——人们常常要用手掩饰。嘻笑、媚笑和鬼脸是求爱阶段的面部表情，人们在社交场合里，常常用手加以掩饰。
在许多文化里，男子常常除去一部分第二性征，把胡须刮掉。女子常除去腋窝里的毛发。腋毛是一种防臭装置，但是在常穿裸肩的衣服时，就得刮掉腋毛。阴毛通常遮掩得严严实实，所以不用刮。有趣的最。艺术模特儿常常要刮掉阴毛，因为他们的裸体没有性的涵义。
此外，人们常常要除去身上的气味。人们沐浴之频繁，远远超过了医疗卫生的目的。社交生活中常常要减轻身体的气昧，去除气味的化学商品的销量很大。
大多数控制机制都采用一种简明扼要、无可辩驳的方式来实现。我们常常把需要限制的东西叫做“不好”、“不行”、“不礼貌”。控制性行为的本意反而难得提到，难得想到。但是，同时运用的还有其它一些控制机制，其形式是人们制定的道德准则和性行为立法。这方面的准则和法律有文化差别，但是一切准则和法律所关注的东西都是一个：防止陌生人之间的性冲动，防止婚外性行为。由于即使在最信奉禁欲主义的清教徒中，这一控制机制也有困难；为了有助于这一控制机制，各种各洋的升华技巧便都使用上了。比如说，学童的体育活动和其它剧烈的体力活动有时就受到鼓励，企图以此来减少性冲动。仔细考察这一观念及其运用就可以看出，一般说来它遭到了可悲的失败，运动员的性欲既不比别人强，也不比别人弱。他们在体力消耗中确有所失，但在身体健康上又有所得。唯一有助于控制机制的办法，看来是悠久的奖惩制度——惩治眈于声色的行为，奖励节制声色的行为。当然，这只能压制冲动，而不能减少冲动。
显而易见，膨胀到不自然程度的社区，需要采取一些控制婚外性行为的步骤，防止强化了的社会接触所导致的配偶之外的性行为，不让它增长到危险的程度。然而，裸猿演化成了一种性行为高度发达的灵长目动物，他采取的控制只能达到这一步。他的生物本性老是不断地在反叛。一种方式的人为控制实行之后，另一种方式的对抗又表现出来。这常常导致荒唐可笑、自相矛盾的局面。
女性要遮掩乳房，可是她接着又用乳罩使乳房隆起。这一性征装置或者是填以衬料，或者可充气膨胀，所以它不仅能恢复掩藏之中的乳房形状，而且能使之膨大。它就这样被用来模仿性冲动时膨大的乳房。有的时候，乳房下垂的女性甚至做整容术，用皮下注蜡的办法达到长期丰乳的效果。
性征衬料也用于身体的其它部分；只需想想过去男士短裤前的悬袋、衬肩和女士们支撑裙子的腰垫，即可窥其一斑。当今一些文化之中，消瘦的女性可以买臀罩或“假胸”。穿高跟鞋引起正常的步态扭曲，从而使臀部的摇晃加剧。
女性的臀部衬垫曾经在不同的时期里采用过，再加上紧束的腰带，臀部和乳房的曲线就显得更加夸张。正由于此，杨柳腰一直受到人们的宠爱，妇女们普遍喜爱束腰。这一潮流发展到半世纪以前“黄蜂腰”那种登峰造极的程度，有的女子甚至做手术取掉最下面的一根肋骨，以收到更好的效果。
广泛使用唇膏、胭脂和香水以增加嘴唇、面颊和身体气味的性感信号，构成了进一步的矛盾。女子精心洗掉身上天生的气味，然后又用商业性的“性感'香水取而代之。这些香水实际上与其它动物的嗅腺分泌物水溶液无异，这些哺乳类可能与人类毫无亲缘关系。
读者看过所有这些各种各样的性限制以及人为的抗衡措施之后，禁不住纳闷，回到起点去不省事得多吗，为何要先在屋子里放冷气，然后又在里面生火呢？正如我已解释过的，限制的原因是直截了当的；是为了防止随意的性刺激，因为它妨碍了配偶的关系。然而，为何又不完全限制其公开表现呢？为何又不把性表现——包括生物的和人为的性表现——局限在配偶之间的私生活中呢？问题的答案有一部分是，人类的性行为高度发达，它要求恒常不断的表现和发泄。它之所以发达，是为了维护配偶的关系：可是现在，在复杂社会充满刺激的气氛中，它常常在非配偶关系中被触发。不过，这仅仅是答案的一部分。性还被用来作为维护地位的手段——这是其它灵长目动物使用的广为人知的策略。如果一只雌猴在不交配的场合去接近一只好斗的雄猴，雌猴就可能使用性表现行为，这不是因为它想交配，而是因为它可以借此而激起雄猴的冲动，而性冲动又可以遏制雄猴的攻击性。这类行为模式被称为诱发新动机的活动。雌猴用性刺激去诱发雄猴新的动机，借此而取得一种不涉及性的好处。人类也借助类似的手段。许多人为的性信号就用在这一方面。使自己吸引异性的注意，可以减少社群里异性成员的对立情感。
当然，这一策略对固定配偶关系的物种来说存在着危险。刺激不能过头。遵守自己文化中基本的性行为限制，就可以明确发出信号：“我不准备那个”；同时又可以发出其它信号：“但是我又非常富于性感”。后者可以减少别人的敌视，前者使情况不至于失去控制。如此而可以求得两全。
这一策略本来应该取得干净利落的效果，可惜还有其它一些影响在起作用。配偶机制并非完美。它不得不嫁接在悠远的灵长目行为系统上，这一点仍要败露出来。一旦配偶关系出了故障，悠远的灵长目动物冲动又会燃烧起来。此外，裸猿巨大的进化发展的特点之一，是童年的好奇心一直维持到成年人生活之中，两者加在一起，情况显然会变得危险。
裸猿行为系统的设计，显然适合这样的情况：女子一个接一个生养一大批孩子，男子与其他男子外出打猎。虽然根本情况保持至今，但是有两点已经变化。出现了人为控制子女人数的倾向。就是说，已婚的女子不再承受生儿育女的全部重压，配偶不在家时，她也有暇过性生活。还有一种倾向：许多女子参加外出狩猎。当然，现在是“工作”代替了古代的狩猎；每日出门工作的男子可能发现自己是在男女混合的群体中生活，而不是在古代那种全由男性组成的狩猎队中生活。这意昧着，配偶双方都有许多东西需要忍受。配偶关系常常受压而崩溃。（你也许能记得，美国的统计数字说明，26％的已婚妇女和50％的男子到40岁时已经有过外遇。）不过，原配关系常常很牢固，足以在有外遇的情况下继续维持下去，或者在外遇过后又重新得以维持。配偶关系最后完全瓦解的情况，只占很小的百分比。
作为一位动物学家，我不能以通常的伦理道德方式去研讨性“怪痹”，诸如观淫癖，手淫，同性恋等。我只能用人口繁殖与否这样的生物伦理原则来讨论问题。如果有什么性模式妨碍生殖，它们就应该被视为货真价实的生物学上不健全的模式。僧侣、修女、长期独身的男子和女士、长期的同性恋者等人群，从人口生殖的意义上说，都是不正常的。社会养育了他们，可是他们并未作出回报。同样，应该认识到，从生殖的角度说，活跃的同性恋者并不比侣侣更异常。还必须说明，没有任何一种性习惯——无论它对某一种文化来说是多么的令人厌恶和淫秽，都不能从生物学的角度去进行批评，只要它不阻碍总的生殖趋势。既使是最稀奇古怪最精心设计的性行为，只要它有助于配偶的受孕，只要它有利于增强配偶的关系，从生殖上来讲，它就完成了使命；从生物学上来讲，它就应该和最“恰当”，最受赞赏的性习俗一样被人们接受。
但我必须指出，有一条重要的例外，以上勾勒的生物伦理道德在人口过分拥挤的情况下似乎并不适用。
人类自己在迅速走向人口过剩这一情景。我们已经到了不容再自负的关头。解决的办法是显而易见的，减低生殖率又不影响现存的社会结构，防止人口数量增加又不阻碍人口质量的提高。避孕技术显然是需要的，但是又不能让它破坏基本的家庭单位。实际上，这种危险微乎其微。尽管有人担心，广泛使用完善的避孕用品会导致乱交，但是这一可能性很小——人类强烈的配偶趋势保证不会发生乱交。
麻烦在于，作为一种性现象，器械的和化学的避孕手段基本上是新鲜事。许多代人体验过避孕、形成了新的传统之后，究竟避孕对社会的基本性结构有何影响，这要过一段时间才弄得清楚。也许它会给社会——性系统造成间接的、难以预测的扭曲或破坏。但是谁知道呢，只有时间才会告诉我们。然而，无论如何，倘若不限制生育，其它选择就更加有害。
记住人口过挤的问题，就可以认为：急剧减少生殖率的需求自然应解除人们对不育人群生物学意义上的批评，这些人有僧侣、修女、长期的单身男女和持久的同性恋者。纯粹从生殖上说，这一看法确有道理，不过它没有考虑其它社会问题；有的时候，除了他们独特的少数人的角色之外，他们也许还得面对其它的社会问题。尽管如此，只要他们在生殖范围之外仍然是善于适应、颇有价值的社会成员、就应该把他们当做是没有给人口爆炸推波助澜的宝贵的社会成员。
回顾人类性行为的整个场景，就可以看出，人类坚守基本生物冲动的程度，比我们原来的想象还要深刻。人类灵长目的性系统经过食肉动物性行为的修正之后，在经历令人叹为观止的技术进步之后，还是完好地保存下来了。倘若把二十家城里人迁移到一个亚热带的原始环境之中，在此环境中，男子不得不外出狩猎觅食，那么这个新部落的性结构几乎不需要任何修正，甚至根本不需要任何修正。事实上，在每一个大城市里发生的情况正是这样的：每个人自有其专门的狩猎（工作）技巧，但是他们的社会——性系统仍然多少保存着原生的形式。科幻作品里描绘的婴儿养殖场、社群性活动、选择性绝育、国家控制的生育分工等构想，并没有成为现实。在飞向月球时，太空猿仍然在自己的皮夹子里珍藏着妻子儿女的照片。只有在普遍的生育限制方面，我们才面对着现代文明的力量对我们悠远的性系统所发动的第一次攻击。由于医学、手术和卫生的改善，我们达到了令人难以置信的生育高峰。我们已经实行了死亡控制，现在还要实行生育控制来求得平衡，看起来，下一世纪里，我们很可能不得不最终改变性行为方式。然而，即使真正改变了性行为方式，那也不是因为它们遭到了失败，而是因为它们太成功了。