One might expect these facts to lead to more trouble than actually occurs, but two things help to prevent this in most cases. Firstly, we are well equipped with a set of instinctive responses to the characteristic sexual signals of the opposite sex, so that we are unlikely to experience a powerful courtship reaction to any object lacking these signals. Secondly, our earliest sexual experiments are of a very tentative nature. We start by falling in and out of love very frequently and very easily. It is as if the process of full imprinting lags behind the other sexual developments. During this ‘searching’ phase we typically develop a large number of minor ‘imprints’, each one being counteracted by the next, until eventually we arrive at a point where we are susceptible to a mayor imprinting. Usually by this time we have been sufficiently exposed to a variety of sexual stimuli to have latched on to the appropriate biological ones, and mating then proceeds as a normal heterosexual process.
It will perhaps be easier to understand this if we compare it with the situation that has evolved in certain other species. Pair forming colonial birds, for example, migrate to the breeding grounds where the nest sites will be established. Young and previously unmated birds, flying in as adults for the first time, must, like all other birds, establish territories and form breeding pairs. This is done without much delay, soon after arrival. The young birds will select mates on the basis of their sexual signals. Their response to these signals will be inborn. Having courted a mate they will then limit their sexual advances to that particular individual. This is achieved by a process of sexual imprinting. As the pair-forming courtship proceeds, the instinctive sexual clues (which all members of each sex of each species will have in common) have to become linked with certain unique individual recognition characters. Only in this way can the imprinting process narrow down the sexual responsiveness of each bird to its mate. All this has to be done quickly, because the breeding season is limited. If, at the start of this stage, all members of one sex were experimentally removed from the colony, a large number of homosexual pair-bonds might become established, as the birds desperately tried to find the nearest thing to a correct mate that was available.
In our own species the process is much slower: We do not have to work against the deadline of a brief breeding season. This gives us time to scout around and ‘play the field’. Even if we are thrown into a sexually segregated environment for considerable periods during adolescence, we do not all automatically and permanently develop homosexual pair-bonds. If we were like the colonial nesting birds, then no young male could emerge from an all-male boarding school (or other similar unisexual organization with the slightest hope of ever making a heterosexual pair bond. As it is, the process is not too damaging. The imprinting canvas is only lightly sketched in most cases and can easily be erased by later, more powerful impressions.
In a minority of cases, however, the damage is more permanent. Powerful associative features will have become firmly linked with sexual expression and will always be required in later bond-forming situations. The inferiority of the basic sexual signals given by a partner of the same sex will not be sufficient to outweigh the positive imprinting associations. It is a fair question to ask why a society should expose itself to such dangers. The answer seems to be that it is caused by a need to prolong the educational phase as much as possible to cope with the enormously elaborated and complicated technological demands of the culture. If young males and females established family units as soon as they were biologically equipped to do so, a great deal of training potential would be wasted. Strong pressures are therefore put upon them to prevent this. Unfortunately, no amount of cultural restriction is going to prevent the development of the sexual system, and if it cannot take the usual route it will find some other.
There is another separate but important factor that can influence homosexual trends. If, in the parental situation, the offspring are exposed to an unduly masculine and dominant mother, or an unduly weak and effeminate father, then this will give rise to considerable confusion. Behavioural characters will point one way, anatomical ones the other. If, when they become sexually mature, the sons seek mates with the behavioural (rather than the anatomical) qualities of the mother, they are liable to take male mates rather than females. For the daughters there is a similar risk, in reverse. The trouble with sexual problems of this sort is that the prolonged period of infantdependency creates such an enormous overlap between the generations, that disturbances are carried over, time after time. The effeminate father mentioned above was probably previously exposed to sexual abnormalities in the relationship between his own parents, and so on. Problems of this kind reverberate down the generations for a long time before they peter out, or before they become so acute that they solve themselves by preventing breeding altogether.
As a zoologist I cannot discuss sexual ‘peculiarities’ in the usual moralistic way. I can only apply anything like a biological morality in terms of population success and failure. If certain sexual patterns interfere with reproductive success, then they can genuinely be referred to as biologically unsound. Such groups as monks, nuns, longterm spinsters and bachelors and permanent homosexuals are all, in a reproductive sense, aberrant. Society has bred them, but they have failed to return the compliment. Equally, however, it should be realised that an active homosexual is no more reproductively aberrant than a monk. It must also be said that no sexual practice, no matter how disgusting and obscene it may appear to the members of a particular culture, can be criticised biologically providing it does not hinder general reproductive success. If the most bizarre elaboration of sexual performance helps to ensure either that fertilisation will occur between members of a mated pair, or that the pair-bond will be strengthened, then reproductively it has done its job and is biologically just as acceptable as the most proper and approved of sexual customs.
Having said all this, I must now point out that there is an important exception to the rule. The biological morality that I have outlined above ceases to apply under conditions of population over-crowding. When this occurs the rules become reversed. We know from studies of other species in experimentally over-crowded conditions that there comes a moment when the increasing population density reaches such a pitch that it destroys the whole social structure. The animals develop diseases, they kill their young, they fight viciously and they mutilate themselves. No behaviour sequence can run through properly. Everything is fragmented. Eventually there are so many deaths that the population is cut back to a lower density and can start to breed again, but not before there has been a catastrophic upheaval. If, in such a situation, some controlled anti-reproductive device could have been introduced into the population when the first signs of over-crowding were apparent, then the chaos could have been averted. Under such conditions (serious over-crowding with no signs of any easing up in the immediate future), anti-reproductive sexual patterns must obviously be considered in a new light.
Our own species is rapidly heading towards just such a situation. We have arrived at a point where we can no longer be complacent. The solution is obvious, namely to reduce the breeding rate without interfering with the existing social structure; to prevent an increase in quantity without preventing an increase in quality. Contraceptive techniques are obviously required, but they must not be allowed to disrupt the basic family unit. Actually there should be little danger of this. Fear has been expressed that the widespread use of perfected contraceptives will lead to random promiscuity, but this is most unlikely, the powerful pair-formation tendency of the species will see to that. There may be some trouble if many mated pairs employ contraception to the point where no offspring are produced. Such couples will put heavy demands on their pair-bonds, which may break under the strain. These individuals will then constitute a greater threat to other pairs that are attempting to rear families. But extreme breeding reductions of this kind are not necessary. If every family produced two children, the parents would simply reproduce their own number and there would be no increase. Allowing for accidents and premature deaths, the average figure could be slightly higher than this without leading to further population increase and eventual species catastrophe.
The trouble is that, as a sexual phenomenon, mechanical and chemical contraception is something basically new and it will take some time before we know exactly what sort of repercussions it will have on the fundamental sexual structure of society after a large number of generations have experienced it and new traditions have gradually developed out of old ones. It may cause indirect, unforeseen distortions or disruptions of the socio-sexual system. Only time will tell. But whatever happens the alternative, if breeding limitation is not applied, is far worse.
Bearing in mind this over-crowding problem, it could be argued that the need to reduce drastically the reproduction rate now removes any biological criticism of the nonbreeding categories such as the monks and nuns, the long-term spinsters and bachelors, and the permanent homosexuals. Purely on a reproductive basis this is true, but it leaves out of account the other social problems that, in certain cases, they may have to face, set aside in their special minority roles. Nevertheless, providing they are well adjusted and valuable members of society outside the reproductive sphere, they must now be considered as valuable non-contributors to the population explosion. Looking back now on the whole sexual scene we can see that our species has remained much more loyal to its basic biological urges than we might at first imagine. Its primate sexual system with carnivore modifications has survived all the fantastic technological advances remarkably well. If one took a group of twenty suburban families and placed them in a primitive sub-tropical environment where the males had to go off hunting for food, the sexual structure of this new tribe would require little or no modification. In fact, what has happened in every large town or city is that the individuals it contains have specialised in their hunting (working) techniques, but have retained their socio-sexual system in more or less its original form. Science-fiction conceptions of baby-farms, communalised sexual activities, selective sterilisation, and state-controlled division of labour in reproductive duties, have not materialised. The space ape still carries a picture of his wife and children with him in his wallet as he speeds towards the moon. Only in the field of general breeding limitation are we now coming face to face with the first major assault on our age-old sexual system by the forces of modern civilisation.
Thanks to medical science, surgery and hygiene, we have reached an incredible peak of breeding success. We have practised death control and now we must balance it with birth control. It looks very much as though, during the next century or so, we are going to have to change our sexual ways at last. But if we do, it will not be because they failed, but because they succeeded too well.
THE burden of parental care is heavier for the naked ape than for any other living species. Parental duties may be performed as intensively elsewhere, but never so extensively. Before we consider the significance of this trend, we must assemble the basic facts.
Once the female has been fertilised and the embryo has started to grow in her uterus, she undergoes a number of changes. Her monthly menstrual flow ceases. She experiences early-morning nausea. Her blood pressure is lower. She may become slightly anaemic. As time passes, her breasts become swollen and tender. Her appetite increases. Typically she becomes more placid.
After a gestation period of approximately 266 days her uterus begins to contract powerfully and rhythmically. The amniotic membrane surrounding the foetus is ruptured and the fluid in which the baby has been floating escapes. Further violent contractions expel the infant from the womb, forcing it through the vaginal passage and into the outside world. Renewed contractions then dislodge and eject the placenta. The cord connecting the baby to the placenta is then severed. In other primates this breaking of the cord is achieved by the mother biting through it, and this was no doubt the method employed by our own ancestors, but today it is neatly tied and snipped through with a pair of scissors. The stump still attached to the infant’s belly dries up and drops off a few days after birth.
It is a universal practice today for the female to be accompanied and aided by other adults while she is giving birth. This is probably an extremely ancient procedure. The demands of vertical locomotion have not been kind to the female of our species: the penalty for this progressive step is a sentence of several hours’ hard labour. It seems likely that co-operation from other individuals was needed right back at the stages where the hunting ape was evolving from its forest dwelling ancestors. Luckily the cooperative nature of the species was growing alongside this hunting development, so that the cause of the trouble could also provide its cure. Normally, the chimpanzee mother not only bites through the cord, she also devours all or part of the placenta, licks up the fluids, washes and cleans her newly delivered infant, and holds it protectively to her body. In our own species the exhausted mother relies on companions to perform all these activities (or modern equivalents of them).
After the birth is over it may take a day or two for the mother’s milk-flow to get started, but once this has happened she then feeds the baby regularly in this way for a period of up to two years. The average suckling period is shorter than this, however, and modern practice has tended to reduce it to six to nine months. During this time the menstrual cycle of the female is normally suppressed and the menstrual flow usually reappears only when she stops breast-feeding and starts to wean the baby. If infants are weaned unusually early, or if they are bottle-fed, this delay does not, of course, occur, and the female can start breeding again more quickly. If, on the other hand, she follows the more primitive system and feeds the infant for a full two-year period, she is liable to produce offspring only about once in three years. (Suckling is sometimes deliberately prolonged in this way as a contraceptive technique.) With a reproductive life-span of approximately thirty years, this puts her natural productivity capacity at about ten offspring. With bottle-feeding or rapidly curtailed breast-feeding, the figure could theoretically rise to thirty: The act of suckling is more of a problem for females of our species than for other primates. The infant is so helpless that the mother has to take a much more active part in the process, holding the baby to the breast and guiding its actions. Some mothers have difficulty in persuading their offspring to suck efficiently. The usual cause of this trouble is that the nipple is not protruding far enough into the baby’s mouth. It is not enough for the infant’s lips to close on the nipple, it must be inserted deeper into its mouth, so that the front part of the nipple is in contact with the palate and the upper surface of the tongue. Only this stimulus will release the jaw, tongue and cheek action of intense sucking. To achieve this juxtaposition, the region of breast immediately behind the nipple must be pliable and yielding. It is the length of ‘hold’ that the baby can manage on this yielding tissue which is critical. It is essential that suckling should be fully operative within four or five days of birth, if the breast-feeding process is to be successfully developed. If repeated failure occurs during the first week, the infant will never give the full response. It will have become fixated on the more rewarding (bottle) alternative offered.