Popular Science Monthly/Volume 37/July 1890/The Musical Sense in Animals and Men
By AUGUST WEISMANN.
THE author, having argued at length that the development of the musical sense is not a result of sexual selection; that it is not a faculty essential to the preservation of the race; and that, as it exists naturally in individuals previous to being cultivated, it is not a faculty that grows with the growth of the race—seeks an explanation of its existence in regarding it as simply a by-product of our organs of hearing. These organs, he goes on to say, are necessary in the struggle for existence, and may therefore have originated and been developed to a high degree in the process of selection. No one can be made to believe that the hand of man was formed with reference to playing the piano. It is adapted to grasping and to delicate touch; and, since these faculties are of great use in the struggle for existence, there was nothing in the way of making a finer fashioning of the hand already present in animals, agreeable with that process. In this way it has become finely fingered, delicate, and flexible as we know it, and as we find it even in the lowest savages. We can do with this hand a great many things that were not contemplated—if we may be permitted the expression—in its structure; among others, play the piano, that instrument having been invented; and a wild African, if we drill him to it from childhood, can, under the conditions of modern piano technics, learn it as well as a civilized child. The same is the case, I believe, to a considerable degree, in the artistic musical sense. That is, in a certain sense, a hand with which we play on the soul, but a hand that was not originally designed for that purpose—that is, did not originate out of the necessity of our discovering music, but out of entirely different necessities. This assertion is in need of a fuller demonstration. Our musical faculties consist of two parts: one, the organs of hearing proper—the outer, middle, and inner ear, which translate the different tones into nerve-movements; and the second, of the brain part, which converts these nerve-movements, when they have passed through the auditory nerve, into tone-perceptions, and the auditory center of the brain.
The first part of this duality—the organ of hearing proper—is not, so far as we know, much more highly developed in man than in many animals; and is not in other ways so constructed that we can conclude that it contains any different capacity from that of those animals for hearing music. The higher animals can also enjoy music, as my house-cat shows, when she comes at the playing of the piano to sit by the player, and sometimes jumps into her lap or on the key-board of the instrument. I know of a dog, too, in a family in Berlin, which comes in in like manner when there is music, often from distant rooms, opening the door with his paw. I knew of another dog, usually thoroughly domestic, which occasionally played the vagabond for love of music. Whenever the semi-annual mass was celebrated in the city he could not be kept at the house. As soon as the so-called Bergknappen, which were accustomed to play at this time in the streets, appeared, he would run away and follow them from morning till evening.
Evidently neither cats nor dogs, nor other animals that listen to human music, were constituted for the appreciation of it, for it is not of the slightest use to them in the struggle for existence. Moreover, they and their organs of hearing were much older than man and his music. Their power of appreciating music is therefore an uncontemplated side-faculty of a hearing apparatus which has become on other grounds what we find it to be. So it is, I believe, with man. He has not acquired his musical hearing as such, but has received a highly developed organ of hearing by a process of selection, because it was necessary to him in the selective process; and this organ of hearing happens also to be adapted to listening to music.
It can not be said that this has been produced in man by natural breeding, or that it may not have been formed previous to the human period. We know nothing of our direct predecessors; and, even if their remains should be found, the bony parts of the organs of hearing in their skulls would furnish no clew to the microscopic particulars of the soft parts with which they were covered during life. It is, however, most probable that the precursors of man had nearly the same organs that he has now; for the living caricatures of men, the apes, have them in nearly the same perfection. We have a right to assume this, although we have not such detailed examinations of these organs as Hasse and Retzius have given us of similar organs in other mammals. We can not determine whether the compass of the scale audible to apes is quite as large as that of men; but we are authorized to presume that it is about the same. The power of perceiving the intervals between musical tones depends on a complicated apparatus in the coil of the ear. This apparatus, called, after its discoverer, the organ of Corti, includes thousands of nervous hair-cells, each of which is excitable only by a single tone of definite pitch. The delicacy of one's auditory apparatus—the correctness of Helmholtz's interpretation of the significance of these organs being presupposed—depends on the number of these hair-cells. According to the exact measurements and enumerations of Retzius, there are 15,500 of them in the ear of man, 12,500 in that of the cat, and 7,800 in that of the rabbit. Hence man has a more perfect hearing than those animals, although we are not able yet to determine whether his superiority consists in finer delicacy or greater compass; possibly in both. There are also differences, but probably not of great extent, in the number of auditory cells between men; and we can explain by these differences why some persons can hear more sharply, or lower tones or higher tones, than others. I myself have a passably fine musical ear, but I can not hear the high tones in which certain species of grasshoppers make music, though hundreds of them may be "fiddling" at the same time, and although other persons recognize them without difficulty.
The question now arises how, if only useful qualities become established, this property of perceiving musical tones, possessed by rabbits and cats in substantially nearly the same degree with man, originated. It must be a matter of indifference to these animals, which do not make music, whether they have a musical sense or not, and the development of their hearing apparatus must have gone on with reference to other needs of theirs. What were those needs? In what respect is it useful to animals to have the power of perceiving so great a number of distinct tones as are provided for in their hearing apparatus? The question has never been discussed, and I confess that the answer is not easy, if a full and detailed explanation is sought. But in a general sense the reason seems easily comprehensible. Wild animals need a very fine ear—beasts of prey, like cats, in order that they may hear and distinguish all the tones that are emitted by their game. A considerable scale is at once in demand for this; one, for example, which shall enable the wild cat to distinguish the cooing of the dove, the call of the cuckoo through all its tones, and those of the thrush, finch, linnet, pheasant, and the other birds and little animals of the wood and field. The wild animal must also be able to distinguish the sounds of his enemies—whether it be the intended victim having to escape his pursuer, or the beast of prey avoiding a rival; to the list of which, already large, has been added man, who appeared after animals' organs of hearing were fully developed. For this purpose the hearing of these animals should be capable of perceiving low tones and high tones, and the complete series of tones between. A feeling of wonder comes over us when we see how highly developed the hearing of animals is, and we can hardly comprehend it except we consider to what an extent their existence in the wild condition depends upon an extreme delicacy of the organ. There must be no uncertainty in their minds as to the kind of source whence any sound comes. A mistake may be a matter of life and death to them. The food of a beast of prey is precarious, and he can not afford to let any opportunity of supplying himself pass. It is not for nothing that the fox watches night and day intent to take notice of the lightest movement in the air; or that the hare is a proverbially timid beast, for the existence of his species depends upon his being on the alert. We can thus understand to a certain extent why the rabbit has 7,800 auditory cells in his organ; a number that represents a wonderfully delicate refinement in his hearing, even if we do not suppose each of these 7,800 cells to correspond with a different tone, as, if we regard each cross-shaped group of four cells as representing a single tone, this would give an exceedingly large number—about two thousand—of tone-perceptions. We may realize how delicate must be the hearing that appreciates even a thousand tones when we recollect that our concert-piano scales give only eighty-seven tones. Even if we take a scale of greater compass, as of a hundred tones at intervals of a semitone, our rabbit will have capacity to distinguish nineteen intertones in each half-tone interval. We, ourselves, if we exercise our full power of hearing, could distinguish some thirty intertones between the tones A and Bb, of our scale—a few more than the difference in the number of vibrations corresponding with those notes (A=440, Bb=467·5).
To make this highly developed organization of the ear of real benefit to the animal, the parts of the brain corresponding with the auditory nerves must be constituted with like delicacy. So also must those parts which serve for the remembrance of sensations. For, without memory and the power to profit by the lessons of experience, those powers would be of little use to the animal.
It is only in a few instances that we can ascertain with any degree of sufficiency how far an animal is capable of really comprehending our music. The capacity often appears to be considerable; for it is well known that cavalry-horses frequently learn to recognize the signals given by the trumpeters as well as their riders do, and to make the motions answering to them before they are directed to do so. We have, furthermore, in many birds, which are far below the mammals we have named in mental capacity, good evidence that our music can be heard and comprehended by beings whose hearing apparatus has not been adapted to those ends. I refer especially to birds which have no or only very simple songs of their own, and are yet able to imitate both the more varied songs of other birds and human melodies. This is conspicuously the case with some of the parrots, which can learn to repeat short melodies well and distinctly. They also possess the proper organs for hearing music, although they do not themselves make it. Thus our proposition seems well founded that, as man possessed musical hearing organs before he made music, those organs did not reach their present high development through practice in music.
Among the objections that may be brought up against this theory, the most real is that founded on the existence of persons without musical sense; who can hear ordinary sounds and intonations as well as musically gifted persons, but who can not define musical intervals, can not take up a melody and repeat it, and can not analyze harmonies. If their organs of hearing are as well developed as those of musicians, that would seem to be evidence that the musical sense is something else than ordinary hearing, and supplementary to it. But it has not been demonstrated that the hearing of unmusical persons is as well developed as that of musicians, and I regard it as highly improbable. Although we have no accurate data on the subject, the facts we have do not sustain the proposition. The idea of unmusicality is a relative one. Mozart had so wonderful a recollection of tone-pitches that he could detect a difference of a quarter of a tone between a violin he was playing and one which he had played on two days before. Other men, whom we regard as men of high musical talent, have only the weakest, or no memory at all, for absolute tone-pitches. They can not tell whether a piece is played in A, C, or F, but are satisfied if the tone-intervals within the piece are properly represented. Defects of this kind are corollaries of want of practice, and result to a large extent from the considerable part which the piano fills in musical teaching. The sense of players on the violin—an instrument on which minute intervals of tone can be produced—is much clearer and more delicate than that of players on the piano. The various degrees of defect in musical sense seem to me to depend on a more or less imperfect structure of the organs of hearing. Defects and aberrations appear in all parts of the body, and must be particularly apt to overtake an organ which, like the ear of man, is now no longer of the importance for maintaining the species which it must have been several thousand years ago when man was still in a state of nature. Or there may be defects in the brain-centers that receive the nervous impressions, or in the connections between the brain and nerves. Light is cast upon these instances through the accounts of cases of aphasia and musical impotency, in which, through injury to a small spot in the brain, the faculty of appreciating or producing music is partly or wholly removed, usually in connection with disorders of speech. Besides the older observations of Kussmaul, Kast, Knoblauch, and Oppenheim have made interesting contributions on this difficult and complicated subject.
Have we a right to suppose that the musical gifts of the primitive man were the same as we have to-day? Can we imagine that men were born in the earliest ages who might have furnished a Haydn, Mozart, or Beethoven, or have acquired even the average musical skill of our day? I do not believe it; for something else is needed for the comprehension of our present higher music than the musical apparatus of our ear and brain-center, and more than the musical instruction that can be given in one person's lifetime—a refined, impressionable, cultivated soul.
The auditory center of the brain often spoken of is not simply theoretical, but is defined with fair certainty. If, in a dog or an ape, a particular spot in the temporal fold of the cerebrum is destroyed on both sides, the animal will be made deaf, although his ear-organs have not been disturbed. The animal's general health is not impaired; it continues to live, but it ceases to hear. Noises passing through its hearing apparatus still excite nervous vibrations, and these are still transmitted to the brain; but the organ is lacking there which should convert them into tone-perceptions and bring them to consciousness. The animal is "soul-deaf." If, again, we were able to remove all the other parts of the cerebellum and leave the hearing centers untouched, the mechanical process of the production of tone impressions would still go on, but the animal or the man would hear nothing, because there would be nothing left in his brain to make him conscious of the tone-impressions. With the rest of the cerebellum was taken away the intellect, with all its side-faculties of feeling, fancy, selfconsciousness, etc. The "soul" is wanting, and without it the finest musical notes, brought to place in the hearing center, make no impression.
I have brought forward this hypothetical case to show that the way in which music is comprehended depends not only on the auditory centers, but as much on that which lies behind them, which takes up the tone-images formed by them and gives them reality—the "soul." If there is no "soul," as in the supposed case, then the tone-images are not perceived; if a highly developed, tuneful, and thoughtful human soul is present, then the confluent and contrasted voices of a polyphone music are perceived as a charming musical structure, a rich art-picture, the single parts of which stand in perceptible connection; going out from one another, running back into one another, the individual tone-pictures shape themselves by ever new variations into ever new and interesting combinations. But if there is only the relatively lowly organized brain of an animal, a parrot, for instance, then the spiritual power of the complicated tone-picture will not prevail, and only a possibly pleasant confusion of sounds is perceived. The parrot will never be able to follow the course of a piece of music, because he lacks the necessary degree of intelligence, but will only be able to repeat snatches of it, with no comprehension of the connection of the parts. Hence we conclude that affections of the same organs of hearing and of the auditory centers appertaining to them must produce different effects on the "soul" according to its degree of development. The "soul" is in a manner played upon by the musical movements of the auditory centers as if it was an instrument; the more complete the instrument, the greater the effect. Hence the comprehension of our music by the highest animals—the dog, the cat, and the horse—is exceedingly imperfect, because of their limited mental development. Music strikes them as pleasant or unpleasant, or attracts them, independently of what we call the character of the piece. The same differences, except in a lesser degree, must prevail in the different stages of development of the human soul. If the primitive man did not have a mind equal to ours; if man's intellect and all that depends upon it has been growing sharper and more profound during the thousands of years of his struggle for existence, his faculty for comprehending music must also have been enlarged in the course of time. For this reason we can not suppose that any Beethovens were concealed among primitive men, or are running around among contemporary Australians or negroes. For that is needed, not only a strongly cultivated musical sense, but also a rich, great, deeply emotional soul such as accompanies an intellect schooled according to the sum of its experiences. I will go further, and say that I do not believe that a child of one of these primitive men, if he were given to us to-day, could be trained to the same degree of musical appreciation as our children are capable of. The native higher mental faculties would be wanting in him. While savages are lower in mental development than civilized man, and while we recognize that man's receptivity for music has grown with his mental development, we must doubt if any increase in the power of the human mind has taken place in historical times. The civilized natives of antiquity appear to have already reached a very high degree of mental capacity; and their lawgivers, poets, philosophers, architects, and sculptors have had no successors superior to them. We have a right to suppose also that the ancients had the same musical sense and talent for music as we; and that, if their music was inferior, it was not for lack in that direction, but for the want of the products of the continued exercise of the musical talent—of invention and discovery—acquired and transmitted from generation to generation, and added to, by the aid of which we have reached our high degree of cultivation. Although man's physical power may not increase, we have a right to expect an almost unlimited advance of mankind in mental cultivation, by each generation building upon the stage which its predecessor had reached, and thus continuing perpetually to go higher.