C P Blacker, R A Fisher and L Penrose on Eugenic Fundamentals

Blacker’s creation of opportunities for Penrose to put his views to the Eugenics Society can be seen as part of his effort to make its members scientifically more respectable, less prejudiced and less class conscious . In this he was successful in that he persuaded them to listen to and discuss with informed scientific speakers. Of these Penrose was the most outspokenly critical on several fundamental issues. Penrose’s value as a critic of the Eugenic Society’s strategy arose from his widespread, detailed knowledge of mental deficiency which he fitted logically into its biological setting and which was later illumined particularly by his familiarity with the advances in knowledge of the fundaments of inheritance made after 1956, to which he himself made important contributions, and in the understanding of their function as the vehicle of human inheritance. His most acute criticism of the Eugenic Society’s theory, projects and methods arose from three sources:

1. His comprehensive, revolutionary work on the nature, causes and heredity of mental deficiency.

2 His appreciation of the difference between what had recently been discovered and become the scientific view of the mechanism of heredity and the widely held Eugenic Society’s view, as aphorised in the description ‘Like breeds like’ and demonstrated by the successful breeding on this principle of horses, dogs, cattle, pigs and other animals serving human purposes, for specialist functions by stock breeders untrained in science.

3. The importance of statistics in research as for instance the ascertainment of the statistical significance of the differences found between groups of individuals when they are compared in respect of the proportion of each group showing a selected characteristic. Pauline Mazumdar says of him:

‘Penrose, indeed, was the Society's most persistent critic in the years after the Second World War. He never let slip an opportunity for pointing out the flaws in every aspect of the eugenists’ arguments.’¹⁸

The most comprehensive expression of Blacker’s views on eugenics appear in his book Eugenics: Galton and After (1952) which is presented in its Introduction as

and it represents an extended account of Blacker’s beliefs, aspirations, plans and hopes for the Society. His chapter on ‘Developments in Genetics’, shows his wide, up to date reading on the subject and the influence of his erstwhile tutor in biology at Oxford [Sir] Julian Huxley. He includes in it a short exposition of Mendelian Principles of Heredity and the most recent discoveries in genetics which are preceded however by the following caveat;

The exuberant sweep of this statement shows the doctrine embodied clearly as a source of the energy which Blacker still devoted to the ‘mainstream’ policy of the Eugenics Society on which Penrose states his opinion in his review of Blacker’s book in the Listener (1952). Penrose attributed the persistence of this ‘mainline’ eugenic tenet to Galton whose

‘scientific observations and inventions contributed to an extraordinary variety of subjects but with eugenics, a term used first by Galton in 1883 to signify the study and practice of race improvement, the situation was a little different. The scientific detachment characterising his attitude in other fields was not maintained. As Dr Blacker shows clearly in his book the subject was to be understood as a system of principles determined by a kind of religious sentiment. This attitude has been copied by many of the participants in the eugenic movement, an activity which Galton initiated and which owes a great deal in England to the work of Dr Blacker’²¹

By deprecating the ‘knowledge of Mendelian principles of chromosomes or genes’ Blacker blinded himself to an impassable obstacle that renders futile the attempt to achieve a eugenic objective by employing the method of reducing the fecundity of people harmfully affected genetically and/or the parents and sibs of such in all but a small number of rare inherited conditions. The example of the stockbreeders who, ignorant of genetics, successfully raise specialised plants or animals cannot be transferred to realise the human stock-improving aspirations of Blacker because in their pragmatic métier they mainly breed for single easily identifiable and assessable items such as colour of fur in cats, speed in race horses or robust strength in cart horses as opposed for instance to honesty, reliability and intelligence in humans. Any failures to breed the anticipated characters can be learned from without the far-reaching undesirable consequences that might occur in such trials in a human population. In addition these pragmatic breeders can observe many generations of their subjects whereas it would be unusual for an observer to oversee more than two human generations in a lifetime. It is genes not qualities that are inherited and it is only in particular cases (eg the blood groups) that characters can be used as precisely as genes can for eugenic purposes. Penrose later says

Penrose demonstrates this difficulty in detail in his paper entitled ‘Phenylketonuria – a problem in eugenics’²³ (1968). This condition, then considered very rare which manifests itself as severe mental defect, was drawn to attention by the Norwegian biochemist Fölling (1934)²⁴ who showed that phenyl-pyruvic acid is excreted in the urine of affected individuals which can be detected by a simple chemical test. Although subjects have a number of unusual phenotypic characteristics their physical appearance is not strikingly unusual on casual observation. The disease is transmitted by recessive inheritance in which both parents are indistinguishable from normal but each carries a single gene for phenylketonuria which becomes manifest however only in individuals who have inherited two genes for the condition, one from each parent. If the affected individual were to have children these would not be affected unless the partner of the phenylketonuric patient was a carrier of the faulty gene. The disease occurs on average in a quarter of the children of a mating where both parents carry a gene for phenylketonuria. On the eugenic problem Penrose points out that 1% of the population of this country are carriers of phenylketonuria; that is they are normal individuals who carry a single faulty gene and they are not detectable. (He also incidentally points out that no cases of phenylketonuria have been reported among individuals of Jewish or Negro origin). Thus this serious inherited condition demonstrates the futility of attempting a eugenic solution by sterilisation or contraception for a condition transmitted by recessive heredity. He points out the only practical medical advice would be to reduce the incidence of phenylketonuria by advising those proposing consanguineous matings in affected families of the risk of having affected offspring instead of trying to reduce the prevalence of the single gene. Some reduction in the incidence of this would also occur from the discouragement of all cousin matings likely to result in pregnancy as it would in all recessively inherited conditions.

The Eugenics Society did travel further along the scientific lines, in which Blacker in some ways did so much to encourage them, so far as to take account of Penrose’s criticism; but that was after 1960 when Blacker retired from his secretaryship of the Society.

I am indebted to Dr A W F Edwards for information about Leonard Darwin and to Professor J Edwards, Professor S Hodgson, Professor J Penrose and Dr M Keynes for many helpful suggestions.

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