This difference is a question of brain, not voice. The chimpanzee has a vocal apparatus that is structurally perfectly capable of making a wide variety of sounds. There is no weakness there that can explain its dumb behaviour. The weakness is centred inside its skull.
Unlike chimpanzees, certain birds have striking powers of vocal imitation. Parrots, budgerigars, mynah birds, crows, and various other species can reel off whole sentences without batting an eyelid, but unfortunately they are too bird-brained to make good use of this ability. They merely copy the complex sequences of sounds they are taught and repeat them automatically in a fixed order and without any reference to outside events. All the same, it is astonishing that chimpanzees, and monkeys for that matter, cannot achieve better things than they do. Even just a few simple, culturally determined, words would be so useful to them in their natural habitats, that it is difficult to understand why they have not evolved.
Returning to our own species again, the basic instinctive grunts, moans and screams that we share with other primates are not thrown out by our newly-won verbal brilliance. Our inborn sound signals remain, and they retain their important roles. They not only provide the vocal foundation on which we can build our verbal skyscraper, but they also exist in their own right, as species-typical communication devices. Unlike the verbal signals, they emerge without training and they mean the same in all cultures. The scream, the whimper, the laugh, the roar, the moan and the rhythmic crying convey the same message to everyone everywhere. Like the sounds of other animals, they relate to basic emotional moods and give us an immediate impression of the motivational state of the vocaliser. In the same way we have retained our instinctive expressions, the smile, the grin, the frown, the fixed stare, the panic face and the angry face. These, too, are common to all societies and persist despite the acquisition of many cultural gestures.
It is intriguing to see how these basic species-sounds and species-faces originate during our early development. The rhythmic crying response is (as we know all too well) present from birth. Smiling arrives later, at about five weeks. Laughing and temper tantrums do not appear until the third or fourth month. It is worth taking a closer look at these patterns. Crying is not only the earliest mood signal we give, it is also the most basic. Smiling and laughing are unique and rather specialised signals, but crying we share with thousands of other species. Virtually all mammals (not to mention birds) give vent to high pitched screams, squeaks, shrieks, or squeals when they are frightened or in pain. Amongst the higher mammals, where facial expressions have evolved as visual signalling devices, these messages of alarm are accompanied by characteristic ‘fear-faces’. Whether performed by a young animal or an adult, these responses indicate that something is seriously wrong. The juvenile alerts its parents, the adult alerts the other members of its social group.
As infants a number of things make us cry. We cry if we are in pain, if we are hungry, if we are left alone, if we are faced with a strange and unfamiliar stimulus, if we suddenly lose our source of physical support, or if we are thwarted in attaining an urgent goal. These categories boil down to two important factors: physical pain and insecurity. In either case, when the signal is given, it produces (or should produce) protective responses in the parent. If the child is separated from the parent at the time the signal is given, it immediately has the effect of reducing the distance between them until the infant is held and either rocked, patted or stroked. If the child is already in contact with the parent, or if the crying persists after contact is made, then its body is examined for possible sources of pain. The parental response continues until the signal is switched off (and in this respect it differs fundamentally from the smiling and laughing patterns).
The action of crying consists of muscular tension accompanied by a reddening of the head, watering of the eyes, opening of the mouth, pulling back of the lips, exaggerated breathing with intense expirations and, of course, the high-pitched rasping vocalisations. With older infants it also includes running to the parent and clinging. I have described this pattern in some detail, despite its familiarity, because it is from this that our specialised signals of laughing and smiling have evolved. When someone says ‘they laughed until they cried’, he is commenting on this relationship, but in evolutionary terms it is the other way round, we cried until we laughed. How did this come about? To start with, it is important to realise how similar crying and laughing are, as response patterns. Their moods are so different that we tend to overlook this. Like crying, laughing involves muscular tension, opening of the mouth, pulling back of the lips, and exaggerated breathing with intense expirations. At high intensities it also includes reddening ok the face and watering of the eyes. But the vocalisations are less rasping and not so high-pitched. Above all, they are shorter and follow one another more rapidly. It is as though the long wail of the crying infant has become segmented, chopped up into little pieces, and at the same time has grown smoother and lower.
It appears that the laughing reaction evolved out of the crying one, as a secondary signal, in the following way. I said earlier that crying is present at birth, but laughing does not appear until the third or fourth month. Its arrival coincides with the development of paternal recognition. It may be a wise child that knows its own father, but it is a laughing child that knows its own mother. Before it has learnt to identify its mother’s face and to distinguish her from other adults, a baby may gurgle and burble, but it does not laugh. What happens when it starts to single out its own mother is that it also begins to grow afraid of other, strange adults. At two months any old face will do, all friendly adults are welcome. But now its fears of the world around it are beginning to mature and anyone unfamiliar is liable to upset it and start it crying. (Later on it will soon learn that certain other adults can also be rewarding and will lose its fear of them, but this is then done selectively on the basis of personal recognition.) As a result of this process of becoming imprinted on the mother, the infant may find itself placed in a strange conflict. If the mother does something that startles it, she gives it two sets of opposing signals. One set says, ‘I am your mother-your personal protector; there is nothing to fear,’ and the other set says, ‘Look out, there’s something frightening here.’ This conflict could not arise before the mother was known as an individual, because if she had then done something startling, she would simply be the source of a frightening stimulus at that moment and nothing more. But now she can give the double signal: ‘There’s danger but there’s no danger.’ Or, to put it another way: ‘There may appear to be danger, but because it is coming from me, you do not need to take it seriously.’ The outcome of this is that the child gives a response that is half a crying reaction and half a parental-recognition gurgle. The magic combination produces a laugh. (Or, rather, it did, was back in evolution. It has since become fixed and fury developed as a separate, distinct response in its own right.)
So the laugh says, ‘I recognise that a danger is not real,’ and it conveys this message to the mother. The mother can now play with the baby quite vigorously without making it cry. The earliest causes of laughter in infants are parental games of ‘peek-a-boo’, handclapping, rhythmical knee-dropping, and lifting high. Later, tickling plays a major role, but not until after the sixth month. These are all shock stimuli, but performed by the ‘safe’ protector. Children soon learn to provoke them—by play-hiding, for example, so that they will experience the ‘shock’ of discovery, or play teeing so that they will be caught.
Laughter therefore becomes a play signal, a sign that the increasingly dramatic interactions between the child and the parent can continue and develop. If they become too frightening or painful, then, of course, the reaction can switch over into crying and immediately re-stimulate the protective response. This system enables the child to expand its exploration of its bodily capacities and the physical properties of the world around it.
Other animals also have special play signals, but compared with ours they are unimpressive. The chimpanzee, for instance, has a characteristic play-face, and soft play-grunt which is the equivalent of our laughter. In origin these signals have the same kind of ambivalence. When greeting, a young chimpanzee protrudes its lips far forward, stretching them to the limit. When frightened, it retracts them, opening its mouth and exposing the teeth. The play-face, being motivated by both feelings of friendly greeting and fear, is a mixture of the two. The jaws open wide, as in fear, but the lips are pulled forward and keep the teeth covered. The soft grunt is halfway between the ‘oooo-oo’ greeting sound and the scream of fear. If play becomes too rough, .the lips pull back and the grunt becomes a short, sharp scream. If it becomes too calm, the jaws close and the lips pull forward into the friendly chimpanzee pout. Basically the situation is the same, then, but the soft play-grunt is a puny signal when compared with our own vigorous, full-blooded laughter. As chimpanzees grow, the significance of the play signal dwindles even more, whereas ours expands and acquires still greater importance in everyday life. The naked ape, even as an adult, is a playful ape. It is all part of his exploratory nature. He is constantly pushing things to their limit, trying to startle himself, to shock himself without getting hurt, and then signalling his relief with peals of infectious laughter.
Laughing at someone can also, of course, become a potent social weapon among older children and adults. It is doubly insulting because it indicates that he is both frighteningly odd and at the same time not worth taking seriously. The professional comedian deliberately adopts this social role and is paid large sums of money by audiences who enjoy the reassurance of checking their group normality against his assumed abnormality.
The response of teenagers to their idols is relevant here. As an audience, then enjoy themselves, not by screaming with laughter, but screaming with screams. They not only scream, they also grip their own and one another’s bodies, they writhe, they moan, they cover their faces and they pull at their hair. These are all the classic signs of intense pain or fear, but they have become deliberately stylised. Their thresholds have been artificially lowered. They are no longer cries for help, but signals to one another in the audience that they are capable of feeling an emotional response to the sexual idols which is so powerful that, like all stimuli of unbearably high intensity, they pass into the realm of pure pain. If a teenage girl found herself suddenly alone in the presence of one of her idols, it would never occur to her to scream at him. The screams were not meant for him, they were meant for the other girls in the audience. In this way young girls can reassure one another of their developing emotional responsiveness.
Before leaving the subject of tears and laughter there is one further mystery to be cleared up. Some mothers suffer agony from incessantly crying babies during the first three months of life. Nothing the parents do seems to stem the flood. They usually conclude that there is something radically, physically wrong with the infants and try to treat them accordingly. They are right, of course, there is something physically wrong; but it is probably effect rather than cause. The vital clue comes with the fact that this so-called ‘colic’ crying ceases, as if by magic, around the third or fourth month of life. It vanishes at just the point where the baby is beginning to be able to identify its mother as a known individual. A comparison of the parental behaviour of mothers with crybabies and those with quieter infants gives the answer. The former are tentative, nervous and anxious in their dealings with their offspring. The latter are deliberate,
calm and serene. The point is that even at this tender age, the baby is acutely aware of differences in tactile ‘security’ and ‘safety’, on the one hand, and tactile ‘insecurity’ and ‘alarm’ on the other. An agitated mother cannot avoid signalling her agitation to her new-born infant. It signals back to her in the appropriate manner, demanding protection from the cause of the agitation. This only serves to increase the mother’s distress, which in turn increases the baby’s crying. Eventually the wretched infant cries itself sick and its physical discomforts are then added to the sum total of its misery. All that is necessary to break the vicious circle is for the mother to accept the situation and become calm herself. Even if she cannot manage this (and it is almost impossible to fool a baby on this score) the problem corrects itself, as I have said, in the third or fourth month of life, because at that stage the baby becomes imprinted on the mother and instinctively begins to respond to her as the ‘protector’. She is no longer a disembodied series of agitating stimuli, but a familiar face. If she continues to give agitating stimuli, they are no longer so alarming because they are coming from a known source with a friendly identity. The baby’s growing bond with its parent then calms the mother and automatically reduces her anxiety. The ‘colic’ disappears.
Up to this point I have omitted the question of smiling because it is an even more specialised response than laughing. Just as laughing is a secondary form of crying, so smiling is a secondary form of laughing. At first sight it may indeed appear to be no more than a low-intensity version of laughing, but it is not as simple as that. It is true that in its mildest form a laugh is indistinguishable from a smile, and this is no doubt how smiling originated, but it is quite clear that during the course of evolution smiling has become emancipated and must now be considered as a separate entity. High intensity smiling—the giving of a broad grin, a beaming smile—is completely different in function from high-intensity laughing. It has become specialised as a species greeting signal. If we greet someone by smiling at them, they know we are friendly, but if we greet them by laughing at them, they may have reason to doubt it.