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9 February 2022

From the NS archive: Eugenics and heredity

14 June 1924: The case for loading the scales that balance nature and nurture.

By Julian Huxley

In the post-Holocaust world, eugenics has become a discredited idea. Before Hitler’s atrocities, however, it was a subject that enjoyed both widespread acceptance and intellectual credibility. In this piece from 1924, which uses the often distasteful terminology of the day, the evolutionary biologist Julian Huxley – brother of the novelist Aldous – made the case for eugenics. Responding to an earlier piece in the magazine, Huxley, who was to become president of the British Eugenics Society, wrote that “when characters are hereditarily determined, they resist change with an astonishing tenacity” and that the modern world was witnessing “the increase of insanity, the numbers and the prolificacy of the feeble-minded… the survival of the weakly, the over-multiplication at the wrong end [of society]”. These were issues that needed to be faced, he said, and eugenics was key.


To the Editor of The New Statesman

“Lens” [the pseudonym of a regular New Statesman writer] in your issues of May 24th and 17th, has been saying some very hard things about Eugenics, or rather about the Eugenics which he attributes to the Eugenics Education Society. In fact, he has been letting himself go in the most whole-hearted and, doubtless, soul-satisfying manner. But, as sometimes happens when people let themselves go, the emotional intensity thus generated appears to have interfered with his purely intellectual processes: in other words, he has allowed himself to talk nonsense in the service of a cause.

“Lens” writes, that twenty years ago “a measure of influence was accredited to heredity, as against nutrition, which no serious student today would recognise for a moment… Today… the master-word is not heredity, nor infection, but nutrition.”

What exactly “Lens” means to imply by this is not entirely clear. He might be referring to the individual, asserting that the individual’s plasticity was greater than had been supposed; or he might be referring to the race, and saying that modifications might be impressed on the germ-plasm – in other words, that acquired characters are inherited. The latter is indicated by his previous sentence: “Evidently it is conceivable that, just as thin inhalation of lead dust injures the germ plasm, so something else, such as right exposure to sunlight, may improve the germ-plasm.” But I think he is really combining, if perhaps not confusing, the two.

As a matter of fact “Lens’s” statements are much too sweeping. There is no “master-word”. Heredity and environment are each in their own sphere supreme. The matter is really so simple, in principle. Every visible “character” of an animal or plant is the resultant of a long series of developmental processes, in which both inner and outer play their respective parts. The leg or tail of a dog or other mammal, for example, is, within definite limits, typical of the species. But tie up one of the puppy’s forelimbs soon after birth, and its development becomes wholly artificial: the bones grow to nearly their normal length, but are very far from attaining their normal thickness. Or keep a female rat at high temperatures, when its internal temperature increases slightly, and the young it produces will have longer tails.

Something of the typical tail or leg structure is thus an effect of environment. On the other hand, while dog-leg and cat-leg would both respond in a similar way to being up, the detail of claw and bone-proportion would remain wholly distinct: these, apparently, are determined chiefly by internal factors. An even more striking example is given by characters of the same type which have different origins. For instance, Klebs subjected plants to various sorts and combinations of coloured lights, and found that in certain lights the plant would not flower properly, but tended all to vegetative growth. An American plant-breeder, on the other hand, recently found in one of his experimental plots a new variety of tobacco plant which refused to flower. When grown, however, in a special greenhouse in different conditions of illumination and temperature, it flowered and produced seed, and the plants from this seed continued to behave as had their parents.

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I have before me as I write some photographs. One is of three brothers, all between twenty and thirty years old. All seem pretty healthy; but while one brother is of normal stature, the other two look like boys of ten or eleven in stature and in general expression and feature. All were brought up in the same surroundings. Then there is one of a cretinous child, and of its unrecognisable transformation to health after a year’s thyroid treatment. There is also one of an axolotl, the salamander which grows normally to adult estate in the aquatic tadpole phase, and the same animal turned into a land-liver by one injection of thyroid. The cretinous child was cretinous because of something outside itself – its mother’s goitrous condition. The axolotl was aquatic, on the other hand, because it inherits too little thyroid for metamorphosis, and the two dwarfs owed their lack of stature to immutably-determined hereditary factors.

Hundreds of examples could be given. But the whole matter can be summed up in one sentence. When differences are found between individuals of a species, these differences may be due wholly to differences in the hereditary constitution, or they may be due wholly to differences in the outer world, or they may be due partly to the one, partly to the other.

That is the first part of the story; and the second is that when differences are found (by proper experimental analysis) to be due to differences in hereditary constitution – in other words, when characters are hereditarily determined, they resist change with an astonishing tenacity. It is perfectly true, as “Lens” writes, that “something, such as right exposure to sunlight, may improve the germ-plasm”. But all the emphasis should be laid on the may. There is practically no experimental evidence in favour of such a possibility, and a good deal against. Lead, X-rays, alcohol and a few other substances or agencies seem to damage the germ-plasm permanently. The experiments of Kammerer and Pavlov speak for the inheritance of favourable modifications – but numerous workers have failed, on trial, to repeat them. There remains so far as I know only one experiment, and that with microscope and unicellular animals (Paramecium) in which success has been attained, and that only in special circumstances and few cases.

On the other hand, flies have been kept for 200 generations without being allowed to fly – with no results on their power of flight; similar lack of effect has been found with sight after many generations’ confinement in the dark. Attempts at acclimatisation to high temperatures have failed, though continued through scores of generations, to raise the thermal death-point – but I do not wish to present all the evidence for the normal non-heritability of acquired characters and the normal failure to produce adaptive mutations.

It is perfectly possible that we shall find out one day how to produce adaptive mutations (which is the modern way of saying how to make acquired characters hereditary). But what is certain is that adaptive mutations normally do not occur, and that existing hereditary differences normally perpetuate themselves with very considerable indifference to the environment. This is all elementary, and I am half ashamed to write at such length on it. But if, first, the fundamental distinction between germinally-determined and environmentally-determined mutations, and secondly the normal impossibility of changing the one into the other, are not realised at the outset, the whole of the rest of any discussion concerning inheritance is vitiated and futile.

This leaves me little space to deal with “Lens’s” more specific criticisms of Eugenics (or, rather, of Eugenists). I am not concerned to defend the Eugenics Education Society, with whose main aim, however – the scientific study of human heredity and its sociological bearings – I am in complete accord. But “Lens” tries to shirk a disagreeable problem by abusing the plaintiff’s attorney. An essentially similar method is traditionally practised by the ostrich; but in both cases the problem remains, and its disagreeableness tends to increase as a result.

What is the problem? It is briefly this. So far as experiment has at present gone it teaches us that mutations – ie, permanent changes in units of the hereditary constitution – are continually occurring in a small proportion of the individuals of any given species. Further, just as it is unfortunately easier to destroy or dislocate a complex mechanism than to improve it, so unfortunately it seems that more deleterious than beneficial mutations occur – cogs of the hereditary machinery are easily slipped. When selection is operative, as in a state of Nature, individuals with such characters are weeded out. But when it is not operative, they survive and multiply. Further, quite apart from the occurrence of new mutations, every population of plants, animals, or men contains a number of recessive hereditary factors which normally do not produce any effects because they are masked by the corresponding dominant factors. When, however, two individuals each carrying the recessive factor mate, then a quarter of their offspring will show the deleterious character, and, what is more, will breed true if they mate with another “pure recessive”. Such recessive factors probably represent the effects of so many past mutations; in any event they, too, are often deleterious in result.

Finally, everyone will agree that although the selection for success in modern civilised life is rigorous, the selection for survival has been enormously weakened by modern medicine, modern sanitation, modern welfare work and modern pity. What is more, even if selection for success be rigorous, it usually has no racial effect, or indeed the reverse of what one might expect, for during the last fifty or sixty years the tendency has become even more accentuated for the poorest and, on the whole, least desirable elements of the population to have the largest families. Thus, in so far as new deleterious mutations crop out or deleterious recessives appear, they will tend to drift to where selection is least rigorous, and to be exempted from selection or even to multiply with excess rapidity.

There is the problem, and, as I said, a very disagreeable one it is. There is, of course, the credit side of the account – the lengthening of life, the reduction of infectious disease and the rest, ably put by “Lens” in his second article. But there is the other side – the increase of insanity, the numbers and the prolificacy of the feeble-minded and of the moron, the survival of the weakly, the over-multiplication at the wrong end. It is clear that the problem must not and could not be solved by a mere return to barbarism and insanitariness. I find it difficult to believe that many Eugenists have advocated this in the way which “Lens” asserts. The rise of civilisation is bound up with the increasing power of sympathy. But it cannot be solved by laissez faire, nor yet by sunlight, nor any other agency acting on individuals and not on the race.

“Lens” has hardly mentioned sterilisation as a possibility. This has already been tried in Switzerland and various American states for certain delinquents, and has, on the whole, worked well, and it need not be in the least cruel. Perhaps, as Mr Haldane supposes in his Daedalus, we shall come to a Eugenic by tissue culture and artificial fertilisation and artificial rearing, compared with which the Eugenics of the Eugenics Education Society, or even of Plato, would look feeble indeed. That, however, is far ahead; meanwhile, however, do not let us lose sight of the problem because we do not like it. The effects of letting this slide might well go far towards the ruin of our civilisation.

Yours, etc, JS Huxley. New College, Oxford. June 10th.

PS. Since the above was written I have read the further article by “Lens”, in which he attempts to deny to hereditary predisposition any effect in the genesis of tuberculosis. It may perfectly well be that of the differences in resistance to tuberculosis which do occur, much more are dependent on environmental differences, much less on inheritable differences – on that point I am ignorant. But that there must be an inherited predisposition to infection, and that it must vary, appears to me self-evident. The most striking case of that sort is, of course, the lack of resistance to measles found in the inhabitants of the South Seas, and the consequent deadly plague which ravaged the islands when measles was first introduced; but there are many other cases.

An analogous instance in the opposite direction is found in the congenital immunity of many even non-poisonous snakes to snake-venom – a property which has probably made it possible for some of them to evolve a poison-apparatus. I personally firmly believe that most men and women are appallingly far from realising the potentialities of their inheritance, whether of bodily health or mental power. Sunshine, rational diet, education, slum clearances, decent houses, exercise and fresh air – all these are elementary stepping-stones to such realisation. But baboons or savages can have all these advantages, and will not blossom beyond their limits – limits set by their inheritance. I am all with “Lens” in his brave crusades for sunlight and milk and the necessities for a healthy life. But he does not advance his cause by using phrases such as “the ignorant nonsense about heredity”.

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