Popular Science Monthly/Volume 4/November 1873/The Phenomena of Heredity
|THE PHENOMENA OF HEREDITY.|
TRANSLATED BY J. FITZGERALD, A. M.
IN human science there is many a ground of self-satisfaction and of pride for the mind, but there are at the same time reasons for humility and bitter disappointment. Notwithstanding the strenuous efforts and the protracted meditations of the legions of investigators who have gone before us, Nature still has abysses dark and deep before which the keenest sight becomes blindness, courage changes into fear, and assurance into despondency. When we strive to throw some light into these mysterious gulfs, the light does but reveal to us the spectres of our own ignorance, and all that we carry away from the vain attempt is a renewed consciousness of our weakness and indigence. It were wise for us to carry away something more, viz., a useful lesson. Indeed, there is nothing that is better fitted to teach us modesty and patience, to cool down presumptuous ardor, and to put to shame overweening temerity, than the study of those phenomena which Providence would seem to have devised for the express purpose of baffling man's curiosity. And yet many there are who pretend to ignore the wonderful and complex phenomena which occur in regions inaccessible to sight or sense, and who stubbornly question the existence of invisible activities and insensible forces. Such is the fatal skepticism against which we must cite the testimony of the sphinxes that occupy our attention now. The lesson is all the more impressive, inasmuch as, by strange contrast, these questions, so refractory to all manner of theoretic explanation, are precisely the ones with which our empirical acquaintance is fullest. Here a knowledge of effects seems in no wise to pave the way to a knowledge of causes.
These remarks have a special application to the subject of heredity. It is an ascertained fact that the ovum contains in its seemingly homogeneous substance not only the anatomical structure of the individual that is to spring from it, but also his temperament, character, aptitudes, sentiments, and thoughts. The parents place in this molecule the future of an existence which is nearly always the counterpart of themselves physiologically, oftentimes pathologically, and in many instances psychologically. Such are the results of the latest studies into this amazing vital economy; and these we purpose laying before our readers.
Heredity is that biological law in virtue of which living beings tend to transmit to their descendants a certain number of their own characteristic traits. It is a very nice question to decide whether we must class under heredity the transmission of the anatomical forms and physiological functions which constitute the species. At all events, it is plain that in this case the parents are completely and absolutely repeated in the children. Were this not so, there would be no species, but only successions of beings without any relations between them save that of generation. Within the historic limits of experience, the continuous reproduction of specific characters, always identical, or, in other words, the permanent integrity of species, is a fact almost beyond question. The distinctive characters of races and of varieties are transmitted with less regularity and fixity, and it is precisely on the various transformations that these may undergo from one generation to another that a famous school of naturalists rest when they would prove, in a more or less extended sense, the transformation of organisms in time. But more irregular still and more variable is the repetition of those characters which, as being less general than those of a species or a race, may be regarded as belonging to the individual. Thus, in proportion as the characters become more particular and more special, the more are they released from the law of heredity, and the greater is the probability that the children will differ from the parents. Still, observation––an observation as ancient as the human race itself––shows that these characters, though personal, may be transmitted by generation. But within what limits, and under what conditions? This we have to inquire into with all circumspection, for there is no other subject in which one is so much in danger of making missteps, and of slipping on dangerous inclines.
Heredity is especially noticeable in the continuity of physiological and pathological conditions. It is very clearly evident in the expression and features of the physiognomy. This was observed by the ancients; hence the Romans had their Nasones, Labeones, Buccones, Capitones, etc. (Big-nosed, Thick-lipped, Swollen-cheeked, Big-headed). Of all the features, probably the nose is best preserved by heredity: the Bourbon nose is famous. Heredity also manifests itself by fecundity and longevity. In the old French noblesse there were several families which possessed high procreative vigor. Anne de Montmorency, who, at the age of over sixty-five years, could still, at the battle of St. Denis, smash with his sword the teeth of a Scotch soldier who was giving him the death-blow, was the father of twelve children. Three of his ancestors, Matthew I., Matthew II., and Matthew III., taken all together, had eighteen, and of these fifteen were boys. The son and grandson of the great Condé had nineteen between them, and their great-grandfather, who lost his life at Jarnac, had ten. The first four Guises reckoned in all forty-three children, of whom thirty were boys. Achille de Harley had nine children, his father ten, and his great-grandfather eighteen. In some families this fecundity endured through five or six generations. The average length of life depends on locality, diet, stage of civilization, but individual longevity appears to be completely freed from these conditions. It is observed among those who lead the most laborious lives, as well as among those who take the greatest care of their health, and it seems to be connected with some inner power of vitality transmitted to individuals from their forefathers. So well known is this fact that, in England, life-assurance companies receive from their agents statements as to the longevity of the applicants' ancestors. In Turgot's family, the age of fifty-nine was very rarely exceeded, and the man who made that family illustrious had a presentiment, so soon as he had reached fifty, that the close of his life was not distant. Albeit he had all the appearances of good health and of great vigor of temperament, still from that time forward he held himself ready for death, and, in fact, did die at the age of fifty-three.
Heredity often transmits muscular strength and sundry other motor activities. In ancient times there were families of athletes, and the English have families of boxers. The recent researches of Mr. Galton, as to wrestlers and oarsmen, show that the winners in the contests in which these men engage generally belong to a few families in which agility and dexterity are hereditary. Suppleness and grace in dancing are also transmitted, as is shown in the case of the celebrated Vestris family. The same is to be said with regard to various peculiarities of voice, such as stammering, nasality, and lisping. There are several families who are naturally singers. Children born of babbling parents are themselves babblers by birthright. Dr. Lucas cites the case of a servant-maid whose loquacity knew no bounds. She would talk to people till they were ready to faint; but she would also talk to animals and to inanimate things. Even when she was quite alone she talked to herself aloud. She had to be discharged; "but," said she to her master, "I am not to blame; it all comes from my father. He had the same fault, and it drove my mother to distraction; and his father was just as I am."
The heredity of anomalies of organization has been demonstrated in several instances. One of the most singular of these is the case of Edward Lambert, whose whole body, except the face, the palms of the hands, and the soles of the feet, was covered with a sort of shell, consisting of horny excrescences. He was the father of six children, all of whom presented the same anomaly at the age of six weeks. The only one of them who lived transmitted the peculiarity to all his sons, and this transmission, passing from male to male, persisted through five generations. Mention is also made of the Colburn family, where the parents for four generations transmitted to the children what is called sexdigitism, i.e., hands and feet with six digits each. Albinism, halting, hare-lip, and other anomalies, are in like manner reproduced in the progeny. It has been observed that purely individual habits have a like tendency to repeat themselves. Girou de Buzareingues informs us that he knew a man who, when abed, was wont to lie on his back with the right leg crossed on the left. One of his daughters had the same habit from birth; she constantly assumed that position in the cradle, notwithstanding the resistance offered by the swaddling-bands. The same author assures us that he has oftentimes noticed in children other habits no less extraordinary, which they must have received from their parents, and which cannot be attributed either to imitation or to education. Darwin gives another instance: A child had the odd habit of setting its fingers in rapid motion whenever it was particularly pleased with any thing. When greatly excited, the same child would raise the hands on both sides as high as the eyes, with the fingers in rapid motion, as before. Even in old age he experienced a difficulty in refraining from these gestures. He had eight children, one of whom, a little girl, when four years of age, used to set her fingers going and to lift up her hands after the manner of her father. Finally, heredity has been observed in handwriting. There are families in which the special use of the left hand is hereditary. Various peculiarities of sensorial conditions are transmitted in a similar way. Nearly all the members of the Montmorency family were affected with an incomplete strabismus, which used to be called the Montmorency look. The incapacity to distinguish between different colors is notoriously hereditary. The distinguished English chemist, Dalton, and two of his brothers, were thus affected, and hence the affection itself received the name of Daltonism. Deafness and blindness are sometimes hereditary, though not often, and deaf-muteness still more rarely. Some curious instances are given of the transmission of certain perverse tastes. Lucas, according to Zimmermann, relates the following: A man in Scotland was possessed of an irresistible desire of eating human flesh. He had a daughter. Although removed away from her father and mother, who were sent to the stake before she was one year old, and although brought up among respectable people, this girl, like her father, succumbed before her strange craving for human flesh. This is clearly a case allied to insanity.
Insanity is, beyond all doubt, transmitted by heredity. Among 1,375 lunatics Esquirol found 337 cases of hereditary transmission. Guislain and other physicians, on a rough estimate, represent the patients affected with hereditary insanity as one-fourth of the total number of the insane. Moreau, of Tours, and others, hold that the proportion of the former is still greater. The heredity of insanity does not imply merely direct transmission of insanity (alienation), properly so called; hysteria, epilepsy, chorea, idiocy, hypochondria, may result from insanity, and, vice versa, they may produce insanity. In passing from one generation to another, these various neuroses (nervous affections) are in some way transformed into one another.Herpin,of Geneva, has found, in the ancestry of 243 epileptics, seven epileptics, 21 insane, and 21 individuals who had suffered from cerebro-spinal affections. Georget, from numerous observations made at the Salpêtrière, came to the conclusion that hysterical women have always near relations who are hysterical, epileptical, hypochondriac, or insane. Moreau calls attention to the "prodigious quantity" of morbid nervous conditions to be found in the ancestry of idiots and imbeciles. A single fact will give the means of judging of the varied and odd complications occurring in the hereditary transmission of neuroses. Dr. Morel attended four brothers belonging to one family. The grandfather of these children had died insane, their father had never been able to continue long at any thing, their uncle, a man of great intellect, and a distinguished physician, was noted for his eccentricities. Now, these four children, sprung from one stock, presented very different forms of physical disorder. One of them was a maniac, whose wild paroxysms recurred periodically; the disorder of the second was melancholy madness; he was reduced by his stupor to a merely automatic condition. The third was characterized by an extreme irascibility and suicidal disposition. The fourth manifested a strong liking for art, but he was of a timorous and suspecting nature.
Scrofula, cancer, tubercular consumption, syphilis, gout, arthritis, tetter, and, in general, all those chronic constitutional affections which are called diatheses or cachexias, are very often transmitted from parent to child. The heredity of these morbid states is almost as frequent and as well defined as that of the neuroses. "We may also affirm the heredity of skin-diseases, and especially of psoriasis, although in this case heredity is of rarer occurrence.
The evolution of these hereditary maladies is extremely interesting and dramatic. Planted in the children's system as germs, or as mere predispositions, they are sometimes destroyed, beyond the possibility of returning, by a multitude of favorable conditions and precautions: in other instances, they begin at once their fatal work of destruction; or, again, they lie hidden for years, reappearing at length, remorseless and terrible, under the influence of sundry exciting causes. Thus age, sex, temperament, practices, habits, hygiene, surrounding conditions, act a part in the development of hereditary morbid activities. Insanity is rare in childhood, and epilepsy most commonly makes its appearance in youth. Hysteria, scrofula, rachitism, and tubercle, appear in childhood and in youth, while gout, gravel, calculus, alopecia, and cancer, are hereditary states of the adult. Women are more liable to insanity, epilepsy, and hysteria, than men; but men, on the other hand, are far oftener than women attacked by gout, gravel, and calculus. The nevous temperament favors neuroses; the lymphatico-sanguine, arthritis and tetter; and the lymphatic, scrofula. The changes occurring in the physiological equilibrium of an individual have a very definite action on the movements and aspects of constitutional affections. Thus, insanity oftentimes appears following menstruation, pregnancy, or childbirth; and, in like manner, epilepsy and hysteria manifest themselves at the first appearance of the signs of puberty. Education and habits exercise a similar influence. Harsh usage and excessive severity, as also complete lack of discipline and watchfulness, have often deplorable effects on the brain of children. Alcoholic excesses and high living are extremely injurious to those whose parents had the gout or the gravel, just as squalor and bad air decimate those who have in themselves the germs of consumption.
This much at least is certain, that the fatal character of hereditary disease is a great and mournful fact, of which they alone are fully and sadly conscious who have daily to witness its consequences. One must see the premature infirmity, the long-continued suffering, the irreparable catastrophes, the slow, cruel agonies, to which parents oftentimes condemn their children, to form a judgment of the power possessed by the demon of disease which lurks in the depths of their being. We must read the authors who have treated these questions, and especially the great alienists of France, if we would learn what a mysterious and baleful energy is oftentimes brought into the world by the babe as it opens its eyes to the light of day—the poor, innocent, puny creature, which, for this brief moment of illusion, is the object of unbounded joys and blessings, and bright hopes!
In short, we may say that the hereditary transmission, whether of individual peculiarities of anatomical structure and of temperament, or of liability to such and such a morbid condition and the same holds good for certain bodily aptitudes—is a very frequent, though not constant, phenomenon in animals and in man.
Hereditary transmission of individual peculiarities of the mental or affectional kind, and of aptitudes for such and such speculative or moral activities, is also a phenomenon which may be observed, though more rarely than that just mentioned. When we go through the series of instances and authorities got together and cited by certain writers, we are struck, it is true, by the apparent force of their arguments, and one is ready to assign to heredity a large share in the development of intellect and character, in the genesis of the thinking individual. We do not see, we forget, the immense number of facts which stand on the other side. The illusions of these mirages have not been useless, seeing that they have led to researches of great interest; but they would be dangerous if they were to be taken by the public as demonstrating the conclusions drawn by some writers. We will state, in brief, the substantial benefits accruing from the researches, and we will then try to refute the conclusions.
According to Galton, the memory was so notable a faculty in the family of the celebrated English Hellenist, Porson, as to have passed into a by-word, the Porson memory. Lady Hester Stanhope, she whose life was so full of adventure, gives, as one among many points of resemblance between herself and her grandfather, her retentive memory. "I have my grandfather's gray eyes," said she, "and his memory of places. If he saw a stone on the road, he remembered it: it is the same with myself. His eye, which was ordinarily dull and lustreless, was lighted up, like my own, with a wild gleam whenever he was seized with passion." The imaginative and creative faculties, those which play the chief part in art and in poetry, are sometimes transmitted from father to son. Galton, in the work he published four years ago ("Hereditary Genius"), and Ribot, in his recent book, give long lists of painters, poets, and musicians, in order to show the part played by heredity in the genesis of these artists' talents. There are in these lists many instances in which this influence of heredity is indubitable, but there are far more in which it is very questionable indeed. Thus, these authors see the influence of heredity in the poetic genius of Byron, Goethe, and Schiller, because they find in the ancestors of these poets certain passions, vices, or qualities—just as though these peculiarities of character could determine poetic genius. The fact is, these lists do not show us any great poet who received his faculties from his ancestors. We do there find that a great poet is sometimes the father of mediocre poets—which is a different thing. The heredity of aptitudes for painting is better established: in a list of 42 celebrated painters, Italians, Spaniards, and Flemings, Galton shows that 21 had illustrious ancestors. The names of Bellini, Caracci, Teniers, Van Ostade, Mieris, Vandervelde, and Vernet, will suffice to prove that there are families of painters. In the family of Titian we find nine painters of merit. The history of music presents instances still more striking. The Bach family took its rise in 1550, and became extinct in 1800. Its head was Veit Bach, a baker at Presburg, who used to seek for relaxation from labor in music and song. He had two sons, who commenced that unbroken series of musicians of the same name, who, for nearly two centuries, overran Thuringia, Saxony, and Franconia. They were all organists, church singers, or what is called in Germany city musicians. When they became too numerous to live all together, and the members of this family were scattered abroad, they resolved to meet once a year, on a stated day, with a view to keep up a sort of patriarchal bond of union. This custom was kept up until nearly the middle of the eighteenth century, and oftentimes more than 100 persons bearing the name of Bach, men, women, and children, were to be seen assembled. In this family are reckoned 29 eminent musicians, and 28 of a lower grade. Mozart's father was second capellmeister to the prince-bishop of Salzburg. Beethoven's father was tenor in the chapel of the Elector of Cologne: his grandfather had been chanter, and then master in the same chapel. Rossini's parents played music at fairs.
We find almost as effectual and continuous an intervention of heredity in the transmission of passions and sentiments of a very different order—those which incline to vice. The liking for strong drink, habits of debauch, a passion for gambling, acquire in some persons a degree of force which can be accounted for only by some fatal organic predisposition derived from their ancestors. "A lady with whom I was acquainted," says Gama Machado, "and who possessed a large fortune, was possessed of a passion for gambling, and passed whole nights at play: she died young, of a pulmonary complaint. Her eldest son, who was in appearance the image of his mother, had the same passion for play. He died of consumption, like his mother, and about the same age. His daughter, who resembled him, inherited the same tastes, and died young." The heredity of a disposition for theft, rape, murder, and suicide, has been proved in several instances.
In proportion as you rise above the purely physiological and pathological regions to those where the mind's activity takes a larger part, heredity is found to lose force and constancy of action. There have been families of scientists—the Cassinis, Jussieus, Bernouillis, Darwins, Saussures, Geoffroys, Pictets. In literature and erudition, the names of Estienne and Grotius, and others, occur. The Mortemarts were famous for their wit. A genius for statesmanship or for generalship has sometimes been perpetuated for several generations in certain families. On the whole, these cases of the transmission of psychical qualities are not frequent. Their being so carefully noted and so set in relief is apparently due to the fact that they are not of common occurrence; and besides, in many of these cases, education had probably more to do than heredity.
Some years ago there appeared a book entitled "Phrenyogenie," in which is to be found, side by side with many chimerical and paradoxical statements, one reflection worthy of attention, and this all the more because it takes account of a peculiarity which appears to have escaped the physiologists hitherto. The author of that book, M. Bernard Moulin, strives to prove that children are living photographs of their parents, as they were at the moment of conception. According to him, the parents transmit to the children the tastes and aptitudes, the spontaneous or the elicited exercise of which was then at the maximum. The broad conclusions which Moulin draws from his researches, as to the art of procreating superior children, may perhaps call forth a smile, but the facts cited by him in support of his views are curious. Here are a few of them: Nine months before the birth of Napoleon I., Corsica was all in confusion. The celebrated Paoli, at the head of an army of citizens which he himself had raised, was endeavoring to put an end to the civil war, and to prevent an invasion by foreigners. Charles Bonaparte, his aid-de-camp and secretary, displayed great courage at the side of his commander. The young officer had with him his wife, Letitia Ramolino, a woman of Roman beauty, and of a strong and masculine character. Napoleon was conceived in his tent, on the eve of a battle, at the distance of two paces from the batteries which faced the enemy. Robespierre was born in 1758, the year which saw Damiens tortured and dragged about the Place de Grève, a year of war, of famine, and of discontent. His father was an attorney, and an insatiable reader of the "Contrat Social." Peter the Cruel, King of Castile, was the son of Alfonso XI., who was ever at variance with his wife. Scandalous scenes of anger, jealousy, and rage, continually disturbed the royal household, and the fruit of the commerce of this wedded pair was Peter the Cruel, a monster of ugliness, physical and moral. History shows to us the parents of Raffaelle both devoted to the art of painting. The wife, a true Madonna, delighted in subjects where grace and piety prevailed; the husband, a great dauber, preferred strength for his part.
M. Ribot, in the remarkable work which he has just written on the subject of heredity, investigates the laws of this mysterious influence, which he regards as a sort of habit, an eternal memory. These laws are little more than a statement of the habitual directions of hereditary impulsion. Sometimes heredity passes from the father to the daughter, from the mother to the son; again the child inherits from both parents. Finally, it often happens that the child, instead of resembling his immediate parents, resembles one of his grandparents, or some remote member of a collateral branch of the family. This is called atavism. This fact was well known to the ancients. Montaigne regarded it with wonder. "Is it not astonishing," says he, "that this drop of seed from which we are produced should bear the impression not only of the bodily form, but also of the thoughts and the inclinations of our fathers? Where does this drop of water keep this infinite number of forms? and how does it bear these likenesses through a progress so haphazard and so irregular that the great-grandson shall resemble the great-grandfather, the nephew the uncle?" Montaigne's wonder has good ground; nor do we to-day know any better than those of the sixteenth century the causes of these strange transmissions.
Such are the facts. In vain would we multiply them, or comment upon them, to change their character. Cases of heredity will never be, in the domain of physiology, any thing more than exceptions, as compared with the cases which make against heredity. But now, if these are only exceptions, by what right shall any man set up heredity as the general law of the development of intellectual activity, or affirm that heredity is here the law, non-heredity the exception? Ribot accumulates the subtlest of arguments to strengthen this singular proposition, but he is wasting his time, wasting his talent. Explain as you will how the heredity of intellectual aptitudes is almost ever overcome by antagonistic or disturbing causes, the fact remains that heredity has not the upper hand. With what ingenious reasons soever you console yourself on seeing the ideal sovereignty of heredity brought down, in matter of fact, to a very low grade of authority, still heredity is not helped. In a word, if non-heredity has in fact a far wider empire than heredity, the question arises, Why does M. Ribot adopt a formula which implies the contrary?
Besides, does not the history of the development of civilization itself show existing in man the preponderant force of an eternal tendency to metamorphosis, to innovation, and to change? Fixedness of thoughts and immobility of habits were, it is true, the law of primitive peoples, as they still are of savage tribes; but then there is nothing to show that this is owing to heredity. This more or less protracted repetition of identical societies should rather, we think, be attributed to the strong and irresistible instinct of imitation and to the profound respect entertained for rites and customs established by religion. Among such peoples the future is like the present, and the present like the past, because the same inflexible rule, the same authority, and the same tyrannical superstition are imposed on them all. Nothing possesses strength or obtains respect except through tradition, and tradition among such people is only the revered memory of the will of the mysterious powers, manifested in days of yore. When the English would have the Hindoos take a part in road-building and the hygienic improvement of their country, they have still to show that the usefulness of such enterprises was understood by the most ancient Brahmans—so hard is it for this old race to conceive of a law which should be obligatory without being traditional.
However that may be, and whatever part heredity may act here, certain it is that this part is not important, since this singular homogeneity of primitive races, instead of being maintained and growing stronger, does, sooner or later, give place to diversity. Every people is in turn invaded by a force at once capable of acting counter to its hereditary influences, and of releasing it from the iron yoke of antique customs. It was in Greece that about 3,000 years ago the first movement of this force brought about what Goethe calls "the liberation of humanity." Since that day the crossings of distinct races, the many new wants, and the various inventions to which they have given rise, and the ideas which men, owing to their more and more intimate contact with Nature, have conceived, have set in the place of primitive simplicity a multiple and irresistible variability, as the present state of the world clearly shows.
- Simple alcoholic intoxication may pass into profound neuroses. Children conceived during an acute attack of intoxication are often epileptic, insane, idiots, etc. These facts were observed long ago. A law of Carthage forbade all beverages except water on the
day of marital cohabitation, and Amyot says that "drunkenness genders naught that is sound." Recent accurate observations have shown that the child that is conceived in a fit of alcoholic delirium, though the latter be only transitory, carries forever the ineffaceable marks of a more or less profound degeneracy.