Part 6

A medical man writes of twins with whom he is well acquainted: "Whilst I knew them, for a period of two years, there was not the slightest tendency towards a difference in body or mind; external influences seemed powerless to produce any dissimilarity." The mother of two other twins, after describing how they were ill simultaneously up to the age of fifteen, adds, that they shed their first milk teeth within a few hours of each other.

Trousseau has a very remarkable case (in the chapter on Asthma) in his important work, "Clinique Médicale." It was quoted at length in the original French in Mr. Darwin's "Variation Under Domestication," vol. ii. p. 252. The following is a translation:

"I attended twin brothers so extraordinarily alike, that it was impossible for me to tell which was which without seeing them side by side. But their physical likeness extended still deeper for they had, so to speak, a yet more remarkable pathological resemblance. Thus, one of them, whom I saw at the Néothermes at Paris, suffering from rheumatic ophthalmia, said to me, 'At this instant, my brother must be having an ophthalmia like mine;' and, as I had exclaimed against such an assertion, he showed me a few days afterwards a letter just received by him from his brother, who was at that time at Vienna, and who expressed himself in these words: 'I have my ophthalmia; you must be having yours.' However singular this story may appear, the fact is none the less exact: it has not been told to me by others, but I have seen it myself; and I have seen other analogous cases in my practice. These twins were also asthmatic, and asthmatic to a frightful degree. Though born in Marseilles, they never were able to stay in that town, where their business affairs required them to go, without having an attack. Still more strange, it was sufficient for them to get away only as far as Toulon in order to be cured of the attack caught at Marseilles. They travelled continually, and in all countries, on business affairs, and they remarked that certain localities were extremely hurtful to them, and that in others they were free from all asthmatic symptoms."

I do not like to pass over here a most dramatic tale in the Psychologie Morbide of Dr. J. Moreau (de Tours), Médecin de l'Hospice de Bicetre. Paris, 1859, p. 172. He speaks "of two twin brothers who had been confined, on account of monomania, at Bicetre.... Physically the two young men are so nearly alike that the one is easily mistaken for the other. Morally, their resemblance is no less complete, and is most remarkable in its details. Thus, their dominant ideas are absolutely the same. They both consider themselves subject to imaginary persecutions; the same enemies have sworn their destruction, and employ the same means to effect it. Both have hallucinations of hearing. They are both of them melancholy and morose; they never address a word to anybody, and will hardly answer the questions that others address to them. They always keep apart and never communicate with one another. An extremely curious fact which has been frequently noted by the superintendents of their section of the hospital, and by myself, is this: From time to time, at very irregular intervals of two, three, and many months, without appreciable cause, and by the purely spontaneous effect of their illness, a very marked change takes place in the condition of the two brothers. Both of them, at the same time, and often on the same day, rouse themselves from their habitual stupor and prostration; they make the same complaints, and they come of their own accord to the physician, with an urgent request to be liberated. I have seen this strange thing occur, even when they were some miles apart, the one being at Bicetre and the other living at Sainte-Anne."

Dr. Moreau ranked as a very considerable medical authority, but I cannot wholly accept this strange story without fuller information. Dr. Moreau writes it in too off-hand a way to carry the conviction that he had investigated the circumstances with the sceptic spirit and scrupulous exactness which so strange a phenomenon would have required. If full and precise notes of the case exist, they certainly ought to be published at length. I sent a copy of this passage to the principal authorities among the physicians to the insane in England, asking if they had ever witnessed any similar case. In reply, I have received three noteworthy instances, but none to be compared in their exact parallelism with that just given. The details of these three cases are painful, and it is not necessary to my general purpose that I should further allude to them.

There is another curious French case of insanity in twins, which was pointed out to me by Professor Paget, described by Dr. Baume in the Annales Medico-Psychologiques, 4 série, vol. i., 1863, p. 312, of which the following is an abstract. The original contains a few more details, but it is too long to quote: Francois and Martin, fifty years of age, worked as railroad contractors between Quimper and Châteaulin. Martin had twice had slight attacks of insanity. On January 15, a box in which the twins deposited their savings was robbed. On the night of January 23-4 both Francois (who lodged at Quimper) and Martin (who lived with his wife and children at St. Lorette, two leagues from Quimper) had the same dream at the same hour, three A. M., and both awoke with a violent start, calling out, "I have caught the thief! I have caught the thief! they are doing injury to my brother!" They were both of them extremely agitated, and gave way to similar extravagances, dancing and leaping. Martin sprang on his grandchild, declaring that he was the thief, and would have strangled him if he had not been prevented: he then became steadily worse, complained of violent pains in his head, went out of doors on some excuse, and tried to drown himself in the River Steir, but was forcibly stopped by his son, who had watched and followed him. He was then taken to an asylum by gendarmes, where he died in three days. Francois, on his part calmed down on the morning of the 24th, and employed the day in enquiring about the robbery. By a strange chance he crossed his brother's path at the moment when the latter was struggling with the gendarmes; then he himself became maddened, giving way to extravagant gestures and making incoherent proposals (similar to those of his brother). He then asked to be bled, which was done, and afterwards, declaring himself to be better, went out on the pretext of executing some commission, but really to drown himself in the River Steir, which he actually did, at the very spot where Martin had attempted to do the same thing a few hours previously.

The next point which I shall mention, in illustration of the extremely close resemblance between certain twins, is the similarity in the association of their ideas. No less than eleven out of the thirty-five cases testify to this. They make the same remarks on the same occasion, begin singing the same song at the same moment, and so on; or one would commence a sentence, and the other would finish it. An observant friend graphically described to me the effect produced on her by two such twins whom she had met casually. She said: "Their teeth grew alike, they spoke alike and together, and said the same things, and seemed just like one person." One of the most curious anecdotes that I have received concerning this similarity of ideas was that one twin A, who happened to be at a town in Scotland, bought a set of champagne glasses which caught his attention, as a surprise for his brother B; while at the same time, B, being in England, bought a similar set of precisely the same pattern as a surprise for A. Other anecdotes of a like kind have reached me about these twins.

The last point to which I shall allude regards the tastes and dispositions of the thirty-five pairs of twins. In sixteen cases--that is, in nearly one half of them--these were described as closely similar; in the remaining nineteen they were much alike, but subject to certain named differences. These differences belonged almost wholly to such groups of qualities as these: The one was the more vigorous, fearless, energetic; the other was gentle, clinging, and timid: or, again, the one was more ardent, the other more calm and gentle; or again, the one was the more independent, original, and self-contained; the other the more generous, hasty, and vivacious. In short the difference was always that of intensity or energy in one or other of its protean forms: it did not extend more deeply into the structure of the characters. The more vivacious might be subdued by ill health, until he assumed the character of the other; or the latter might be raised by excellent health to that of the former. The difference is in the key-note, not in the melody.

It follows from what has been said concerning the similar dispositions of the twins, the similarity in the associations of their ideas, of their special ailments, and of their illnesses generally, that the resemblances are not superficial, but extremely intimate. I have only two cases altogether of a strong bodily resemblance being accompanied by mental diversity, and one case only of the converse kind. It must be remembered that the conditions which govern extreme likeness between twins are not the same as those between ordinary brothers and sisters (I may have hereafter to write further about this); and that it would be wholly incorrect to generalize from what has just been said about the twins, that mental and bodily likeness are invariably co-ordinate; such being by no means the case.

We are now in a position to understand that the phrase "close similarity" is no exaggeration, and to realize the value of the evidence about to be adduced. Here are thirty-five cases of twins who were "closely alike" in body and mind when they were young, and who have been reared exactly alike up to their early manhood and womanhood. Since then the conditions of their lives have changed; what change of conditions has produced the most variation?

It was with no little interest that I searched the records of the thirty-five cases for an answer; and they gave an answer that was not altogether direct, but it was very distinct, and not at all what I had expected. They showed me that in some cases the resemblance of body and mind had continued unaltered up to old age, notwithstanding very different conditions of life; and they showed in the other cases that the parents ascribed such dissimilarity as there was wholly, or almost wholly, to some form of illness. In four cases it was scarlet fever; in one case, typhus; in one, a slight effect was ascribed to a nervous fever: then I find effects from an Indian climate; from an illness (unnamed) of nine months' duration; from varicose veins; from a bad fracture of the leg, which prevented all active exercise afterwards; and there were three other cases of ill health. It will be sufficient to quote one of the returns; in this the father writes:

"At birth they were exactly alike, except that one was born with a bad varicose affection, the effect of which had been to prevent any violent exercise, such as dancing, or running, and, as she has grown older, to make her more serious and thoughtful. Had it not been for this infirmity, I think the two would have been as exactly alike as it is possible for two women to be, both mentally and physically; even now they are constantly mistaken for one another."

In only a very few cases is there some allusion to the dissimilarity being partly due to the combined action of many small influences, and in no case is it largely, much less wholly, ascribed to that cause. In not a single instance have I met with a word about the growing dissimilarity being due to the action of the firm, free will of one or both of the twins, which had triumphed over natural tendencies; and yet a large proportion of my correspondents happen to be clergymen whose bent of mind is opposed, as I feel assured from the tone of their letters, to a necessitarian view of life.

It has been remarked that a growing diversity between twins may be ascribed to the tardy development of naturally diverse qualities; but we have a right, upon the evidence I have received, to go further than this. We have seen that a few twins retain their close resemblance through life; in other words, instances do exist of thorough similarity of nature, and in these external circumstances do not create dissimilarity. Therefore, in those cases, where there is a growing diversity, and where no external cause can be assigned either by the twins themselves or by their family for it, we may feel sure that it must be chiefly or altogether due to a want of thorough similarity in their nature. Nay further, in some cases it is distinctly affirmed that the growing dissimilarity can be accounted for in no other way. We may therefore broadly conclude that the only circumstance, within the range of those by which persons of similar conditions of life are affected, capable of producing a marked effect on the character of adults, is illness or some accident which causes physical infirmity. The twins who closely resembled each other in childhood and early youth, and were reared under not very dissimilar conditions, either grow unlike through the development of natural characteristics which had lain dormant at first, or else they continue their lives, keeping time like two watches, hardly to be thrown out of accord except by some physical jar. Nature is far stronger than nurture within the limited range that I have been careful to assign to the latter.

The effect of illness, as shown by these replies, is great, and well deserves further consideration. It appears that the constitution of youth is not so elastic as we are apt to think, but that an attack, say of scarlet fever, leaves a permanent mark, easily to be measured by the present method of comparison. This recalls an impression made strongly on my mind several years ago by the sight of a few curves drawn by a mathematical friend. He took monthly measurements of the circumference of his children's heads during the first few years of their lives, and he laid down the successive measurements on the successive lines of a piece of ruled paper, by taking the edge of the paper as a base. He then joined the free ends of the lines, and so obtained a curve of growth. These curves had, on the whole, that regularity of sweep that might have been expected, but each of them showed occasional halts, like the landing places on a long flight of stairs. The development had been arrested by something, and was not made up for by after growth. Now, on the same piece of paper my friend had also registered the various infantile illnesses of the children, and corresponding to each illness was one of these halts. There remained no doubt in my mind that, if these illnesses had been warped off, the development of the children would have been increased by almost the precise amount lost in these halts. In other words, the disease had drawn largely upon the capital, and not only on the income, of their constitutions. I hope these remarks may induce some men of science to repeat similar experiments on their children of the future. They may compress two years of a child's history on one side of a ruled half-sheet of foolscap paper if they cause each successive line to stand for a successive month, beginning from the birth of the child; and if they mark off the measurements by laying, not the 0-inch division of the tape against the edge of the pages, but, say, the 10-inch division--in order to economize space.

The steady and pitiless march of the hidden weaknesses in our constitutions, through illness to death, is painfully revealed by these histories of twins. We are too apt to look upon illness and death as capricious events, and there are some who ascribe them to the direct effect of supernatural interference, whereas the fact of the maladies of two twins being continually alike, shows that illness and death are necessary incidents in a regular sequence of constitutional changes, beginning at birth, upon which external circumstances have, on the whole, very small effect. In cases where the maladies of the twins are continually alike, the clock of life moves regularly on, governed by internal mechanism. When the hand approaches the hour mark, there is a sudden click, followed by a whirling of wheels; at the culminating moment, the stroke falls. Necessitarians may derive new arguments from the life histories of twins.

We will now consider the converse side of our subject. Hitherto we have investigated cases where the similarity at first was close, but afterwards became less: now we will examine those in which there was great dissimilarity at first, and will see how far an identity of nurture in childhood and youth tended to assimilate them. As has been already mentioned, there is a large proportion of cases of sharply contrasted characteristics, both of body and mind, among twins. I have twenty such cases, given with much detail. It is a fact, that extreme dissimilarity, such as existed between Esau and Jacob, is a no less marked peculiarity in twins of the same sex, than extreme similarity. On this curious point, and on much else in the history of twins, I have many remarks to make, but this is not the place to make them.

The evidence given by the twenty cases above mentioned is absolutely accordant, so that the character of the whole may be exactly conveyed by two or three quotations. One parent says: "They have had exactly the same nurture from their birth up to the present time; they are both perfectly healthy and strong, yet they are otherwise as dissimilar as two boys could be, physically, mentally, and in their emotional nature." Here is another case: "I can answer most decidedly that the twins have been perfectly dissimilar in character, habits, and likeness from the moment of their birth to the present time, though they were nursed by the same woman, went to school together, and were never separated till the age of fifteen." Here again is one more, in which the father remarks: "They were curiously different in body and mind from their birth." The surviving twin (a senior wrangler of Cambridge) adds: "A fact struck all our school contemporaries, that my brother and I were complementary, so to speak, in point of ability and disposition. He was contemplative, poetical, and literary to a remarkable degree, showing great power in that line. I was practical, mathematical, and linguistic. Between us we should have made a very decent sort of a man." I could quote others just as strong as these, while I have not a single case in which my correspondents speak of originally dissimilar characters having become assimilated through identity of nurture. The impression that all this evidence leaves on the mind is one of some wonder whether nurture can do anything at all beyond giving instruction and professional training. It emphatically corroborates and goes far beyond the conclusions to which we had already been driven by the cases of similarity. In these, the causes of divergence began to act about the period of adult life, when the characters had become somewhat fixed; but here the causes conducive to assimilation began to act from the earliest moment of the existence of the twins, when the disposition was most pliant, and they were continuous until the period of adult life. There is no escape from the conclusion that nature prevails enormously over nurture when the differences of nurture do not exceed what is commonly to be found among persons of the same rank of society and in the same country. My only fear is that my evidence seems to prove too much and may be discredited on that account, as it seems contrary to all experience that nurture should go for little. But experience is often fallacious in ascribing great effects to trifling circumstances. Many a person has amused himself with throwing bits of stick into a tiny brook and watching their progress; how they are arrested, first by one chance obstacle, then by another; and again, how their onward course is facilitated by a combination of circumstances. He might ascribe much importance to each of these events, and think how largely the destiny of the stick has been governed by a series of trifling accidents. Nevertheless all the sticks succeed in passing down the current, and they travel, in the long run, at nearly the same rate. So it is with life in respect to the several accidents which seem to have had a great effect upon our careers. The one element, which varies in different individuals, but is constant in each of them, is the natural tendency; it corresponds to the current in the stream, and invariably asserts itself. More might be added on this matter, and much might be said in qualification of the broad conclusions to which we have arrived, as to the points in which education appears to create the most permanent effect; how far by training the intellect and how far by subjecting the boy to a higher or lower tone of public opinion; but this is foreign to my immediate object. The latter has been to show broadly, and, I trust, convincingly, that statistical estimation of natural gifts by a comparison of successes in life, is not open to the objection stated at the beginning of this memoir. We have only to take reasonable care in selecting our statistics, and then we may safely ignore the many small differences in nurture which are sure to have characterized each individual case.

SIGHT IN SAVAGES

From "Idle Days in Patagonia"

WILLIAM HENRY HUDSON

A person much given to card-playing once informed me that always after the first few rounds of a game he knew some of the cards in the pack, and could recognize them as they were being dealt out, by means of certain slight shades of difference in the colouring of the backs. He had turned his attention to this business when very young, and as he was close upon fifty when he imparted this interesting piece of information, and had always existed comfortably on his winnings, I saw no reason to disbelieve what he told me. Yet this very man, whose vision was keen enough to detect differences in cards so slight that another could not see them, even when pointed out--this preternaturally sharp-eyed individual was greatly surprised when I explained to him that half a dozen birds of the sparrow kind, that fed in his courtyard, and sang and built their nests in his garden and vineyard and fields, were not one but six distinct species. He had never seen any difference in them: they all had the same customs, the same motions; in size, colour, and shape they were all one; to his hearing they all chirped and twittered alike, and warbled the same song.

And as it was with this man, so, to some extent, it is with all of us. That special thing which interests us, and in which we find our profit or pleasure, we see very distinctly, and our memories are singularly tenacious of its image; while other things, in which we take only a general interest, or which are nothing to us, are not seen so sharply, and soon become blurred in memory; and if there happens to be a pretty close resemblance in several of them, as in the case of my gambling friend's half a dozen sparrows, which, like snowflakes, were "seen rather than distinguished," this indistinctness of their images on the eye and the mind causes them all to appear alike. We have, as it were, two visions--one to which all objects appear vividly and close to us, and are permanently photographed on the mind; the other which sees things at a distance, and with that indistinctness of outline and uniformity of colour which distance gives.

In this place I had proposed to draw on my La Plata notebooks for some amusing illustrations of this fact of our two sights; but it is not necessary to go so far afield for illustrations, or to insist on a thing so familiar. "The shepherd knows his sheep," is a saying just as true of this country--of Scotland, at all events--as of the far East. Detectives, also military men who take an interest in their profession, see faces more sharply than most people, and remember them as distinctly as others remember the faces of a very limited number of individuals--of those they love or fear or constantly associate with. Sailors see atmospheric changes which are not apparent to others; and, in like manner, the physician detects the signs of malady in faces which to the uninstructed vision seem healthy enough. And so on through the whole range of professions and pursuits which men have: each person inhabits a little world of his own, as it were, which to others is only part of the distant general blueness obscuring all things, but in which, to him, every object stands out with wonderful clearness, and plainly tells its story.

All this may sound very trite, very trivial and matter of common knowledge--so common as to be known to every schoolboy and to the boy that goeth not to school; yet it is because this simple familiar fact has been ignored, or has not always been borne in mind by our masters, that they have taught us an error, namely, that savages are our superiors in visual power, and that the difference is so great that ours is a dim decaying sense compared with their brilliant faculty, and that only when we survey the prospect through powerful field-glasses do we rise to their level and see the world as they see it. The truth is that the savage sight is no better than ours, although it might seem natural enough to think the contrary, on account of their simple natural life in the desert, which is always green and restful to the eye, or supposed to be so; and because they have no gas nor even candlelight to irritate the visual nerve, and do themselves no injury by poring over miserable books.

Possibly, then, the beginning of the error was in this preconceived notion, that greenness and the absence of artificial light, with other conditions of a primitive life, kept the sight from deteriorating. The eye's adaptiveness did not get sufficient credit. We know how the muscles may be developed by training, that the blacksmith and prizefighter have mightier arms than others; but it was perhaps assumed that the complex structure and extreme delicacy of the eye would make it less adaptive than other and coarser organs. Whatever the origin of the error may have been, it is certain that it has received the approval of scientists, and that they never open their lips on the subject except to give it fresh confirmation. Their researches have brought to light a great variety of eye-troubles, which, in many cases, are not troublesome at all, until they are discovered, named with a startling name and described in terms very alarming to persons of timid character. Frequently they are not maladies, but inherited defects, like bandy legs, prominent teeth, crushed toes, tender skin and numberless other malformations. That such eye-defects are as common among savages as among ourselves, I do not say, and to this matter I shall return later on; but until the eyes of savages are scientifically examined, it seems a very bold thing to say that defective colour-sense is due to the inimical conditions of our civilization; for we know as little about the colour-sense of savages as we do about the colour-sense of the old Greeks. That the savage sight is vastly more powerful than ours was perhaps not so bold a thing to say, seeing that in this matter our teachers were misled by travellers' tales, and perhaps by other considerations, as, for instance, the absence of artificial aids to sight among the children of nature. The redskin may be very old, but as he sits sunning himself before his wigwam in the early morning he is never observed to trombone his newspaper.

The reader may spare himself the trouble of smiling, for this is not mere supposition; in this case observation came first and reflection afterwards, for I happen to know something of savages from experience, and when they were using their eyes in their way and for their purposes, I used mine for my purpose, which was different. It is true that the redskin will point you out an object in the distance and tell its character, and it will be to your sight only a dark-coloured object, which might be a bush, or stone, or animal of some large kind, or even a house. The secret of the difference is that his eye is trained and accustomed to see certain things, which he looks for and expects to find. Put him where the conditions are new to him and he will be at fault; or even on his native heath, set before him an unfamiliar or unexpected object, and he will show no superiority over his civilized brother. I have witnessed one instance in which not one but five men were all at fault and made a wrong guess; while the one person of our party who guessed correctly, or saw better perhaps, was a child of civilization and a reader of books, and, what is perhaps even more, the descendant of a long line of bookish men. This amazed me at the moment, for until then my childlike faith in the ideas of Humboldt and of the world generally on the subject had never been disturbed. Now I see how this curious thing happened. The object was at such a distance that to all of us alike it presented no definite form, but was merely something dark, standing against a hoary background of tall grass-plumes. Our guides, principally regarding its size, at once guessed it to be an animal which they no doubt expected to find in that place--namely, a wild horse. The other, who did not have that training of the eye and mind for distant objects in the desert which is like an instinct, and, like instinct, is liable to mistakes, and who carefully studied its appearance for himself, pronounced it to be a dark bush. When we got near it turned out to be a clump of tall bulrushes, growing in a place where they had no business to grow, and burnt by drought and frosts to so dark a brown that at a distance they seemed quite black.

In the following case the savage was right. I pointed out an object, dark, far off, so low down as to be just visible above the tall grasses, passing with a falling and rising motion like that of a horseman going at a swinging gallop. "There goes a mounted man," I remarked. "No--a traru," returned my companion, after one swift glance; the traru being a large, black, eagle-like bird of the plains. But the object was not necessarily more distinct to him than to me; he could not see wings and beak at that distance; but the traru was a familiar object, which he was accustomed to see at all distances--a figure in the landscape which he looked for and expected to find. It was only a dark blot on the horizon; but he knew the animal's habits and appearance, and that when seen far off, in its low down, dilatory rising and falling flight, it simulates the appearance of a horseman in full gallop. To know this and a few other things was his vocation. If one had set him to find a reversed little s in the middle of a closely-printed page the tears would have run down his bronzed cheeks, and he would have abandoned the vain quest with aching eyeballs. Yet the proofreader can find the little s in a few moments, without straining his sight. But it is infinitely more important to the savage than to us to see things quickly and guess their nature correctly. His daily food, the recovery of his lost animals and his personal safety depend on it; and it is not, therefore, strange that every blot of dark colour, every moving and motionless object on the horizon tells its story better to him than to a stranger; especially when we consider how small a variety of objects he is called on to see and judge of in the level monotonous region he inhabits.