In this book Lynn is concerned by what he sees as the decline in the influence of eugenics and the regression of desirable human attributes of which intelligence is a foremost example. He has written another book dealing more fully with an aspect of this subject to which we are referred in the present volume for data in support of his argument. His publications show that as a psychologist he has rightly concentrated on intelligence. He gives a clear account of the history of the founding aims and aspirations of the Eugenic movement and his knowledge of eugenics in the rest of the developed world has enabled him to make many useful comparisons within the compass of a single volume. One notable absence however is L S Penrose’s contribution to the debate within which eugenics policy has been formed. A surprising new feature however is a look forward to the effect eugenics or its absence may have on national configurations and on the leaders of the World’s future.

The central problem with which he deals is his apprehension of a decline of inheritable intelligence in the population since about the middle of the nineteenth century due to relaxation of natural selection by improved housing, water supplies, welfare, advances in medicine and reduction of infant mortality which has increased the fecundity of the lower class already greater than that of the upper class. It therefore behoves us to check the profligacy of the lower and encourage the fertility of the upper class. Since intelligence is inherited, the author believes this can be done by sterilising mental defectives and offering incentives to have more children (e.g. by children’s education grants) to more intelligent parents. This problem has generated debate throughout three quarters of the last century and two questions can be drawn from it that bear on Lynn’s proposition.

1. Has a continuous decline of intelligence of our national population been demonstrated?

2. Can mental deficiency be abolished or reduced by the scheme of sterilisation that Lynn advocates? The decline in the level of average national intelligence is attributed to the dilution of natural selection by welfare and medical care for infants born handicapped thus increasing their expectation of life and increasing the proportion of the less intelligent. Lynn attempts to demonstrate this by examining the relation of low intelligence and fecundity which is set out in his earlier book to which he refers us. Here he disputes Penrose’s demonstration that genetic analysis of the multigenetic inheritance by which intelligence is distributed to produce an average IQ amongst offspring, approaching the mean IQ of the parents. Thus the overall tendency is for the average IQ level to remain stable. Lynn also disputes Penrose’s statement that ‘Among idiots (IQ 0-19) there is almost complete absence of effective fecundity with imbeciles (IQ 20-49) fecundity is possible but rare’. Lynn’s evidence for this challenge is quoted from Pajema (1968) whose figures taken from Lynn’s 1996 publication are shown in the table overleaf.

Lynn’s rejoinder to the first part of Penrose’s statement that ‘among idiots there is almost complete absence of fecundity’ is that Pajema’s findings (Lynn, 19%, pp 78-79) show that idiots are certainly not childless as is shown in Penrose’s table of his results (reproduced in the table above). However what Pajema’s table in fact shows is that 6 children were born from 3 mothers who were in the IQ group below 55 ie idiots and imbeciles; idiots are not shown separately. There is reason to believe that these 3 mothers were most probably imbeciles for there is another table on p 79, facing page in the same book, deriving from Wailer (1971) and showing similar information to that of Pajema but on a different population of 713 defectives and which also differs in showing the idiot (IQ up to 25) and imbecile results separately. No children at all are shown in either of these sections: individuals in these two intelligence grades are childless. If we now consider Penrose’s findings on the same subject from the very carefully assessed 713 female patients of his ‘Colchester Survey’ research we find no idiot patient had children and there are 16 children (2, p23. Table 14) born of 180 backward (IQ 70-99) patients in this rating group. Thus in all three examples of which Penrose’s is the most reliable, idiots are infertile. It is clear that Lynn’s refutation of Penrose’s statement requires more convincing evidence than he has produced here. Penrose’s finding stands on firm ground and is clearly justified by the evidence from his own research and is compatible with evidence advanced in his book. This is important because Penrose’s results support his view that the very low birth-rate of those with an IQ below 50 balances the low birth rate of those of the population in the top section of the IQ scale and this is part of the mechanism that keeps the average IQ of the population at a relatively stable level. Another test of a decline in mean IQ is a comparison of its measurement in successive generations of school children. The arguments of most of the psychologists referred to by Lynn (p22-23) were disposed of by Penrose (eg Am. J. Ment. Def. 53,11,4-8). Lynn quotes here for instance Sir Godfrey Thomson,a psychologist, who in his Gallon Lecture (Eugen. Rev. 1946, 38,9-18) demonstrated in a group of Scottish school children a positive correlation between higher intelligence and a lower size of family as evidence of declining intelligence. What Lynn has overlooked however is Thomas’s later finding, published in l949 involving a comparison of the test results of two generations of school children a period of ten years apart in which the mean IQ was higher in the later group of children clearly showing that there had been no decline of intelligence during that period.

One thing anticipated by the sterilisation of mental defectives is a contribution to military efficiency compared to the rest of the world. Surely other qualities than the ability to reach an above average score on a measure of IQ contribute to soldierly virtues; physical attributes for instance. We ought to delete all bodily disorders and handicaps. Let us see how Lynn’s argument works out applied to a handicap other than mental retardation; defective vision, for example, quite a large proportion of which is attributable to hereditary defective vision leading to blindness. The therapy which remedies this condition merely preserves the genes causing it and assists their distribution. In pursuit of military excellence and economic superiority we should delete them through a sterilisation programme extended to all defects of sight which show a family incidence – spectacle wearers for instance. The Spartans would have done this had the knowledge of heredity we have been available to them; a warrior had to have two sons before being fit to fight. Can their military efficacy be doubted? This scheme should be recommended to the Chinese to improve and hasten their eugenic journey to become the future dominant nation (see Chap. 21, p315).

Bearing on the second question of the eugenic efficiency of sterilising mental defectives, Penrose’s view was that mental deficiency is not a single condition but is a feature in over a hundred diseases and disorders of which those that are genetically caused vary considerably in their mode of inheritance. Recessive inheritance of the gene, for instance, would elude the sterilisation advocated here because carriers of the gene do not come to attention except by birth of an affected child. Sterilisation then as the author observes (p147) can require ten generations to reduce the initial incidence of the disorder by half and thousands of generations to eliminate. The second source of mental deficiency arises from the distribution of intelligence scores which are continuously graded in the distribution curve of the population (with of those within the range of IQ 50-70 forming a sub-cultural group) in the same way as stature is distributed with no sharp division between the normally intelligent and the subcultural group. ‘Mental defective’ is not a medical diagnosis and in the absence of a knowledge of each underlying medical condition, and if it is hereditary the nature of its genetic mechanism, we cannot know the hereditary outcome and secure an appropriate method for an improved eugenic result with the least possible disadvantage. Identifying blanket sterilisation of mental defectives and their families with the easy rule of thumb method applicable to animals is a false comparison because husbandry deals with readily appreciated, mostly single animal qualities (colour of coat for example); several generations can be covered in the lifetime of one observer and a poor result is not a major disaster. Lynn quotes as an instructive example of animal husbandry methods the system in use for breeding thoroughbred horses for speed. This involves selection from the fastest 10% of stallions and from the 50% of fastest mares. This has produced a roughly 1% yearly average improvement for the whole population of horses born in this way with no improvement of the fastest running speed (p152). It is an excellent portrayal of the accomplishments of animal breeding but there are no comments on its applicability to humans. The rule of like breeds like does not cover the widely varied intellectual level of families with a mentally defective member; in the publication of his seven year study of all the families of 1280 institutionalised defectives² Penrose reports for example that 1% of the sibs of this series are of superior intelligence, 50% are normal, 7% are dull and 7% defective.

Eugenics is, in Galton’s words, to ‘to improve the qualities of the population’ (the population being all mankind) and to this aspiration justice is done in this book; but in its accomplishment science is of great value, particularly genetics and epidemiology when their established methods of enquiry and proved results are adhered to.

References

1. Lynn, R. Dysgenics: Genetic Deterioration in Modern Populations, Praeger, London, 1996.

2. Penrose, L S (1938). A clinical and genetic study of 1280 cases of mental defect. Medical Research Council; Special Report 229.

3. The Scottish Council for Research in Education, Godfrey Thomson (Chairman), London University Press, 1949.

David C. Watt