THE EFFECT OF ENVIRONMENT ON THE ORGANISM.

Otago Daily Times, Issue 19255, 20 August 1924, Page 5

THE EFFECT OF ENVIRONMENT ON THE ORGANISM.

Contributed by tho local branch of the W.E.A. Dr Bonham continued his lecture as follows Although quite a number of experiments have been designed lo test the matter very few of them have given It decisive answer; the majority of the results are vague, inconclusive, and capable on analysis of some other explanation than that the environmental modifications have been inherited. The classic example which has been quoted again and again is that series of experiments conducted by Brown-soquard many years ago, —-the assumed production of epilepsy in guinea pig*. Ho made sever© operations on the animals, cutting through the nerve on the leg or cutting the spinal cord ; the operations were followed by certain symptoms that are associated in with epilepsy. The offspring that were bred from those epileptic guinea pigs also presented certain of those abnormal symptoms, and it has been assumed that the effects of the operation so impress themselves on the body, that tho new character was transmitted. But other more recent experiments, made with a view to confirming these, were found to be negative. When critically examined tho interpretation of tho results was not what "’as assumed originally. Tho operations wore of a very violent character, interfering with tho nutrition and other physiological processes of the animals, aaid leading to a general weakening of them and their germ cells, so that this weakness was handed on to the offspring. It was Bergson who suggested what to-day is regarded as the real cause of the symptoms exhibited by the young ones —that the artificially induced epilepsy liberated a toxin which so affected the germ cells and in some cases the germ colls and the foetus that they were diseased, and hence tho offspring were diseased. I will quote one more experiment. In 1922 Griffiths made a series of experiments with white rats, which are very amenable to tests of various kinds. They were confined in small circular cages mounted on vertical axles so that they were kept In constant rotation day and night for weeks, and even months. After some months’ residence in these cages the rats were removed to terra Anna. They showed permanent changes in bodily structure, and in their posture, for when they walked they walked in a circle, and the head was twisted to the right or left. In short they showed the effects of the environment in which they had lived for months. But pathological results set in, and death ensued. Before, however, this happened, the rats were mated with normal white rats, and these unions gave rise to offspring, some of which showed the signs of abnormal progression. Continued breeding from these even to the fourth generation gave evidence of the same symptoms. Out of a total of 500 offspring as many as 60 of them exhibited these symptoms to some degree. Here wo have the apparent inheritance of these now characters. But one must confess that even here the evidence is not very strong. Nevertheless, this is declared by that strong supporter of Lamarkism to be the most decisive of all the experiments of this matter. Arc we to build on this and other less convincing results so far-rcaehlng a theory as to inheritance as the Lamarkians would uphold? No one supposes that all environmental modifications are inherited, least of all such malformations as the shortened tails of sheep which have been cut for hundreds of generations; nor the deformed feet of Chinese women. But one would expec* that, if there is truth in the theory, that the ‘ children of the long-civilised peoples of the Western world, where reading and writing have been practised for hundreds of years, would to-day be able to read and write with little or no training. Yet there is no evidence, I, believe, that at the present day the children learn to read more quickly than they did in former generations. The shoemaker acquires certain skeletal and muscular peculiarities due to tho position in which he passes much of his time. But do his children present the same peculiarities? Do the blacksmith’s children inherit his more muscular arms? Are tho musician’s children invariably or even occasionally better musicians than their fellows? Do they learn to play sooner? Does the artist transmit his artistic colours? Indeed, it is rarely that the children of intellectual parents present the same kind of intellectuality, though it sometimes happens that they do exhibit a greater degree of brainincss than their fellows. But hero we are again mot with the difficulty of distinguishing between their environment and their inheritance. Being the children of intellectual parents, they inherit their intellectuality. The majority of biologists arc, I think, of an open mind in tho matter; we await more definite proof than is provided by tho few experiments which have a semblance of supporting tho theory; we are doubftul. If it were a fact that these environmental modifications were inherited we should expect to find many positive evidences rather than a few sporadic ones. And if environmental conditions the hereditary constitution of the germ cells we should expect to find that when parts of animals or plants are grafted on one or other each would modify in some way the hereditary constitution of the other. But we don’t. The ovary of a pure black guinea pig wag transplanted into a pure white guinea pig in place of its own ovaries, which were taken away. This white guinea pig with a black ovary was mated with a pure whit© male. Tho litter of offspring were all pure black, although both th© parents were white, all tho children of this first generation were black because they oamo from the germ cells in a black ovary, ingrafted in a white body. The body of the mother—i.e., the new environment of the black ovary did not affect the ovary. Other reasons for the attitude of doubt taken by biologists are the following:—The mechanism of heredity is to-day well known; it is a matter of the chromosomes, minute structures in tho nucleus of the germ colls, and these chromosomes are built up of still more minute particles, each of which has been shown by breeding experiments to represent some particular character of the nidividual-te-g., the colour of tho eyes, and we call them genes. Biologists nave found it difficult, if not impossible, to conceive of any . mechanism by which modifications of tho body, such as result from a reaction to the environment, can be impressed on these germ cells in such a way as that similar modifications will reappear in the next generation. But in view of tho rapid development of wireless telegraphy and telephony wo have become familiarised with a new typo of vibrations of tho ether, so that we can send messages without a connecting wire to almost any distance. It may seem permissible to suggest that the living cells of tho body in which, doubtless, complex vibrations ar© going on, may conceivably influence germ cells, without our being able to demonstrate any material connection for transmission. We may perhaps find help in understanding how this effect may be carried to tho germ cells in the existence of hormones. We know that there are certain glands in various parts of th© which discharge into the blood minute quantities of some substance, possibly of a chemical nature, which have a very considerable effect on even distant organs and the functions of the body as a whole, examples of such glands are the thyroids and tho pituitary. These hormones arc known to regulate nutrition and growth, and are intimately concerned with the mental equipment of the individual his character and his personality. It is possible that it is by means of such hormones that environmental effects on tho body are transferred to (he germ cells, and so affect them that tho effects are transmitted to the offspring. But in any case many generations are required in order that (lie germ cells may be so deeply impressed as to find full expression on tho offspring. Secondly, it is difficult to imagine that a now character suddenly impressed on tho body from without will undo tho work of age-long heredity; or that it will alter tho constitution of the germ plasm in such a way that tho sequence of events which ensue from long-continued repetition by the germ cells in the normal course of development will bo changed. The germ plasm is essentially very conservative, and. although capable of slow changes, it is not apparently capable of beincr affected by the sudden alteration. We admit, of course, that long-continued action of the same environment, generation after generation, may ultimately change the germ, plasm so that some effect will be produced in the offspring. But such response will not necessarily he precisely the same as that originally presented bv the parent. After all experiments in the laboratory are uncertain guides in this matter, for there is no doubt that under the unusual conditions of captivity, and oven of domestication, the physiology of tho animals is altered, and they are apt to he physiologically ahnorrnaJ. Tho results obtained, whatever they may be, are thus due in part to their abnormal physiological state, and hence are unreliable. Nevertheless, it must be confessed that if wo turn from these laboratory experiments to the field and note the series of natural experiments in the modifications that appear in various animals in adaptation to different kinds of surroundings, it is diffi-

cult to avoid the supposition that these adaptations have arisen as a reaction to changes in th© environment. Thus tho ancestors of tho horse can be traced from a three-toed form, living in swampy ground, where splayed feet would be of advantage, through a series of forms in which there is the srradual reduction and disappearance of the outer and superfluous toes till we have the one-toed horse of today adapted to dry ground and to rapid locomotion. Another example is the flightlessnoss of some birds, of which wo in N.Z. have several examples. Now a bird is so eminently a creature whoso entire anatomy is modified in relation to flight that tho existence of birds that cannot fly seems almost a contradiction jn terms. Yet in New Zealand wo have the woka or Maori hen. tho Icakapo or ground parrot, tho kiwi, and the moa. We know from the embryology of the kiwi that it is descended from ancestors that had larger wings than the kiwi has to-day. And the explanation of the present, Sightlessness is that the birds owing to luck of enemies from which flight would save them, ceased to make use of the wings, and so gradually after many generations of disuse, they became slowly reduced in size until to-day they are useless. It is time now to leave these biological experiments and see whether there are any lessons to be learnt from them which may ho applicable to mankind in any attempts that are made towards the betterment of humanity. And the question of all questions for tho sociologist and for all interested in this matter is this;— Are these suddenly acquired characters, due to the action of the environment on mind or body hereditable? The ti - assumption of philanthropists all + *'"‘ ... n the eighteenth and nineteenth centn was that the differences between men an- duo to circumstances and could be abolished by education. We know that racial differences are due to circumstances acting through thousands of years. Yet the idea, that education and environment acting through one or two generations can cancel the work of hundreds of generations of heredity is futile and contrary to all biological evidence. But wo need not despair at this conclusion. An essential thing to bear in mind is that man differs from other animals in having two kinds of inheritance which are often confused owing to the use of the common term inheritance for both. Ho has a biological inheritance, a germinal inheritance, which is real heredity, like that of nil other animals. It is inherent in him. and is responsible for much of his physical and mental condition, and for that instinctive behaviour, often indispensable for actual maintenance of life and health. He has also a social inheritance—not a part of his true heredity—but playing a very important and conspicuous role in bis life, especially in his less material or higher life, in that part of his life, indeed, that especially characterises him as human and above the animals. Man is not born with this social inheritance in him as is his biological inheritance; but with it all around him. He is horn into it rather than with it in hm. This social inheritance consists of tradition, of recorded history, of education. It is possible because of mutual aid and speech because of writing and printing. We do not inherit through our germ cells the effects on our ancestors of their training and environment, hut we do inherit, in the sense of inheriting property, their environment, customs, and institutions. They are inherited through society. And is it not possible that by means of this social inheritance human nature may be slowly changing? It has been said by people who may be opposed to certain radical changes in human society that it will bo necessary “to change human nature” before this or that improvement can come about, implying that it will never come about. But biologists declare that human nature does change and is changing, slowly though it may be and not perhaps so rapidly as some of the ardent reformers hope and believe. It has changed bofh by virtue of strictly biological factors, but especially and more rapidly by virtue of our social inheritance. Human nature today is certainly not the same as it was in early glacial times, when our ancestors lived in Europe. Human nature not only has changed ip time past but it can be made to change in definite directions by education. And it is, I think, generally recog nisod that at the present day the general level of culture is much higher than it was 50 years ago; the regard for the rights of others and for human life; the protective attitude towards children and towards those not so well equipped for life’s struggles have been immensely improved. Social life is on an altogether higher ethical plane. And accompanying this feeling of moral responsibility to our lew fortunate fellows is the recognition that there are certain individuals who are not responsible for their actions—they are in various degrees mentally incapable of keeping within the lines laid down by social conventions for our self-protection and advancement. At an earlier part of this address wo put tile question—Are criminals bom or are they made; Is the criminal tendency tho result of environment or of heredity? I think that an answer can bo given from tho researches made by men in England and America into the problem of mental defectives.

Dr Williams, of California, has published the detailed results of an exhaustive study by him of 470 delinquents, of ages from 6 to 22 years. He finds that about one-third of these juvenile delinquents are feeble-minded, that nearly one-half are border-line to dull normal, whole one-fifth are rated at average normal or superior. It is important to compare the percentage of the various mental rating classes in two groups of 'boys of similar ages from that State —namely, Williams, 470 delinquents; and a group of 1009 boys token at random from all classes of the population, we have tho following suggestive figures. Miscellaneous Delinquents, group, p.c. p.c. Superior rating ... 3 20 Average normal ... 19 60 Dull normal 21 10 Border lino 27 8 Feeble minded ... 30 2

One of the meet interesting practical outcomes of tho intensive study of mental deficiency or subnormancy has been the development of ingenious intelligence tests, Binet, by which a definite rating of intelligence can be determined for any individual. An extensive use of these tests Vas made in America during the war for rating soldiers and officers, and is now in use at some of the American universities in place of an examination, as a test of fitness to enter a university. A valuable feature of these tests is the expression of the result in terms of “Mental Age” which may be contrasted at once with the actual ag© of the individuals tested, so that degrees of mental advancement or of retardation is mad© manifest in readily understandable terms. Thus a child of 12 years of age may bo found to have a “mental age” of only eight years—that is ho is on a par with tho intelligence of an average child of that age. Or he may hav© a mental age of 14 and so be in advance of tho average normal child. And so from a wide experience of these specific ratings certain general categories of mental capacity ami incapacity have teen established, and ar now commonly used by psychologists, at any rate in the U.S.A. At the bottom of the list is feeble-mindodnoas; then follows in ascending order, border lino cases, dull normal, average normal, and highest superior. Much special study has been given to feeble.-miudedncss by students of heredity, and it has been proved without any doubt that this form of mental incapacity is strongly inherited, and follows the Mendclian Law in regard to its mode of inheritance.

This being so, it has obviously a most important significance in connection with the whole problem of education. We must face the situation that there are limits to the educability of certain individuals, and we should call a halt to the vain efforts to put the same kind of education into all kinds of pupils. The association of feeble-mindedness with juvenile delinquency is positive. But it is to bo noted that not all delinquency is duo to foeblo-mindedness, for 19 per cent, are rated as average normal and 3 per cent, as superior. But, one-third of tho juvenile delinquency, which is tho first step towards confirmed adult criminality, is due to hereditary mental deficiency : another third to tho undesirable inherited traits; and tho final third to unfortunae environmental conditions. In other words, part is flu© to nature of the individuals, part to liieir nurture. There are, (lien, two kinds of juvenile delinquencies and two kinds of remedies are required (o combat these causes. One is a remedy of better environment or cnlhenics'; the other is the remedy of being better born—that is, by the introduet ion of eugenies. The latter I shall not have time to discuss to-night, I may explain these two terms—ciithenics is defined as a system of improving the individual by good surroundings. Eugenics is a system of improving tho race by good brooding. Man’s environment is much more complex than that of animals, and its influence on the development greater. In addition to chemical and physical stimuli, which arc potent factors of development in tile case of all animal organisms, man lives in a world of phyehical, social, and moral stimuli, which have a profound influence on

him. He is influenced not only by present environment, but also by memories of past experiences and anticipation of future ones. Moreover, through intelligent and social cooperation, he is able to control his environment for particular ends. On the other hand, heredity is no more powerful as a factor in development in tile case of man than in other organisms, but just as powerful. The period of immaturity of man is longer than in any other animal, and it is during this formative period that environment and education* has the greatest influence. All our social and ethical institutions, such as Government education, religion, deal with environmental factors of development, and life; nevertheless as we have seen there is no evidence that such intrinsic influences modify heredity except in the long run. But though the effects of environment and training on the individual are not transmitted, yet the environmental training and experiece of former generations are handed down to later generations by custom, tradition, and history. No given environment or training can be good for every individual nor for the same individual at every stage of his development. Each individual, is unique and if the best results are to be had must have unique environment and training and must be supplied by omniscient _ intelligence. The impossibility of securing the absolute best conditions of development need not prevent society from securing better conditions than those which now prevail. There is here in New Zealand from time to time a claim made that the university should be free for all—quite ignoring the fact that at the present tiißO it is free to all who are able to reach a terta 'n standard of education, and that not a > -vy high one ; and that the Government, h ‘ means of bursaries, pays the cost rf university training for all those who arc fh -<vj to benefit by it. Quoting from the official year book for 1923, the number of students attending university classes in 1921 was 4123; number of students receiving payment for their education at these colleges (including training colleges; scholars and bursaries), 1655. That is about two-fifths of the total are receiving free education. But it would be useless, and a vast waste of money for buildings and additional staff, to attempt to educate every young person who thought he would like to attend the classes. Ho would soon find that he would not benefit himself, but would be a clog to everv one else. Though it is true that hero in New Zealand we have not so high a. proportion of dull pupils in our schools as in some of the older countries, yet. as the American would say, “You cannot put a thousand dollar education into a fifty dollar boy. There is first of all the difference in hereditable character, as' well as differences in the early environment to contend with. The biologist has a certain positive knowledge of some of the conditions and factors that do help to determine human life, though it is partly determined by a set of conditions which are to a very great extent outside the special knowledge of the biologist He can give a guess about them just as well as other people, but hehas no right to claim that lie knows all about the development of character much depends on. early nurture, education and surrounding influences generally but how the individual reacts must largely depend on his inheritance. . . , - The philosopher William James, in his work, “Energies of Mari,” states: A® * rule men habitually use only a small part of the powers they actually possess and which they might use under appropriate conditions.” It has boon . suggestedl that in these “unrealised potentialities , we reconcile the conflicting evidence m regard to the relative influence of nature and “nurture.” There is an optimum set of conditions which will permit of the maximum- development of any particular character; such optimum conditions are rarely realised ■ the environment may prevent the full development of a character or trait. But no amount of environmental improvement will lead to its development beyond a certain grade fixed by heredity. Unfavourable environment, physical or social, may make a criminal out of a man who might otherwise bo a good citizen, it may make a mediocre man out of a potential genius. But no environment however favourable, can make a good citizen out of a ■"born criminal,” nor an intelligent man out of a congenital dullard. SUMMARY. The environment has very evident and often important effects on the individual human being—for better or worse—but from all we arc able to learn from observations on the lower animals, the effect on the individual, being of a transient nature, is unable to influence the germ cells so as to be transmitted to the immediate offtt is onlv when similar conditions persist for a long period of time so as to affect many successive generations that- the environmental influence becomes hereditary and definite changes in the ; descendants become perceptible. Nevertheless, owing to our social inheritance —our system of custom and education —a gradual change in mental and bodily characteristics is apparent erven in the next generation, leading to progress or to decadence of the race according °as whether the germinal inheritance is favourable or unfavourable. Environment by itself is useless for improving the race unless heredity provides good material upon which it may act. (Note.—The first part of this appeared in our issue of August 6d