Eugenics is a term coined by Francis Galton in 1883, meaning well born, to apply to the study and practice of breeding better plants and animals useful to man, and likewise of safeguarding and improving the human heritage. With the passage of time, the meaning of “eugenics” has come to be restricted to the latter sense. It was defined by Kellicott as “the social Direction of human evolution.”
The social direction of human evolution is no new idea. Man peoples have practiced infanticide in order to red their society of abnormal or defective individuals and to prevent their increase. The ancient Spartans not only did this, but also, in order to maintain their ascendancy over the helots, practiced most of the eugenic measures applied in recent times. For the dominant class, emigration was limited and marriage with those of their own order was encouraged. Celibates bore the weight of special taxes, whereas the production of offspring was rewarded by the state. A severe regimen was maintained to promote fitness and to eliminate the weak or deformed. Also, periodically, the helots were massacred in large numbers, so as always to keep that supposedly inferior element of the population down.
Plato’s proposals for a eugenic society are famous He held that neither defective children nor those produced by inferior parents ought to be reared. Chronic invalids and victims of self-indulgence should be denied medical aid, and the morally degenerate executed. On the positive side, the improvement of the race could be promoted by temporary unions of the best men and women for the specific purpose of creating superior offspring.
These examples are enough to show that nature of the main questions that arise in attempting ‘the social direction of human evolution,’ the questions: what? how? and whither? What is the nature of heredity, the material the eugenist would alter? How readily and by what agents may it be altered? Toward what goals should eugenics be directed? These will be taken up in turn.
We know that to start with, each individual is a fertilized egg cell that must develop the characteristics common to all members of its species, race, and family, besides those traits peculiar to itself. The fertilized egg, then, possesses potentialities and capacities for developing in a certain way, but it can do so only within the limitations of its environment. We therefore need to understand first, the mechanism of heredity (i.e., how the fertilized egg comes to posses its potentialities); and second, the relative power of heredity and environment in molding a person’s traits.
As to the first, the science of genetics informs us that heredity is primarily determined by genes. These hereditary units are present in equal number in each of the reproductive cells (ovum and sperm) that unite in fertilization. Heredity is therefore biparental. Essentially, for each gene inherited from one’s mother, a corresponding gene is inherited from one’s father. Corresponding genes are no always identical, for by rare but permanent changes know as mutations existing genes give rise to dew kinds. Should the two genes forming a pair happened to be different (a condition called “heterozygous”), then one gene, known as the dominant, may determined the specific trait concerned; the other gene, known as the recessive, is then masked, although it will still be transmitted to succeeding generations without ant alteration. Thus a person who has a pair of genes (Bb), one for brown eye-color (B) and the other for blue (d), will have brown eyes, and the presence of the gene for blue eye-color may be quite unsuspected. One can have blue eyes only by inheriting two genes for blue eye-color, one from each parent. (Such a person, with both genes in the pair alike, is said to be “homozygous.”) Dominance is not always the rule, and in some cases one can see the effects of both genes comprising a pair. For example, a pair of genes, one of which produces blood type A and the other blood type B, each person’s genes are probably recessive, and most of these will be heterozygous and as a consequence unobservable. The significance of this for eugenics is unmistakable: a considerable proportion of the genes in any person, and therefore in the entire population, are hidden, and to that extent the measures of eugenics must be applied blindly.
Many characteristics are determined of affected by more than one pair of genes--intelligence, for example. In such a case it is a particular combination of dominant genes (belonging to different pairs), perhaps together with some homozygous recessive genes, that determines the nature of the character. These combinations, however, are very rarely inherited in toto, the reason being that a person does not inherit all the genes of his parents, but only half of those of each parent--specifically, one gene from each pair of the parent’s genes. Pure chance determines which of the two genes of a pair will be chosen. Genes located on different pairs of chromosomes are assorted at random, and even those on the same pair of chromosomes can enter into recombinations to a certain extent. The more genes there are, then, in the combination will be transmitted to the next generation intact. Nearly all combinations are broken up as the germ cells become mature, and then new combinations of biparental origin are formed when egg and sperm cell unite. The importance to eugenics of this reassortment and recombination of genes in heredity can hardly be overemphasized, inasmuch as most of the human genes, the combinations of which cannot be preserved, whether good or bad. Moreover, a particular gene which in most combinations has an adverse effect may, in just the right combinations, produce a desirable effect; and conversely, a particular gene that in most combinations has a favorable effect may get into a bad combination. We can scarcely estimate the absolute, over-all effect of a gene; we must judge it by the company it keeps.
Galton was the first person to try to assess the relative powers of heredity and environment in determining a person’s characteristics. His investigations of the familial occurrence of genius and of special talents convinced him that “the power of nature was far stronger than the power of nurture, when the nurtures of the persons being compared were not exceedingly different . . . [i.e.,] 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.” Later studies have largely confirmed this judgment. In particular, studies of monozygotic, or so-called “identical,” twins, who develop from a single fertilized ovum and who therefore share an identical heredity, indicate that even when the twins are separated from early infancy, they remain astonishingly similar. This similarity is greatest in physical traits, such as eye color, hair color, blood types, baldness, or the possession of other distinctive features, all of which remain virtually identical in the co-twins. There is a a somewhat greater resemblance in height than in weight, yet in both these respects the correlation is nearly complete. There is remarkable similarity in length of life. Insusceptibility to diseases, such as cancer or appendicitis, and especially in the tendency to develop the same defects of metabolism, such as diabetes or allergy, the twins also are markedly alike. Adult one-egg twins, few of whom were living together at the time, have been found to agree in the occurrence of tuberculosis in 87 per cent of the pairs of twins. But ordinary dizygotic twins, who come form two different eggs fertilized separately, and who therefore stand midway between monozygotic twins and unrelated persons in the proportion of genes they share, showed a concordance of only 26 per cent; and husbands and wives, as examples of unrelated persons living together and sharing the same environment, showed a concordance of only 7 per cent. The correlation of I.!. (intelligence quotient) for one-egg twins reared apart is no higher than that of two-egg twins of the same sex reared together. This means that a similar environment has about the same effect in making the I.Q.’s alike as does the genetic difference between the two-eggs twins and the identical twins. Among twenty pairs of one-egg twins reared apart, ten pairs did not differ significantly; six pairs differed by 7 to 12 I.Q. points, and four pairs by 15 to 24 pants. The biggest difference here is about equal to a full grade in the distribution: idiot--insanity--moron--low--average--superior--very superior--genius. That difference occurred in a pairs of twins who differed by more that thirteen years of education; and no big difference was found between twins reared apart except where the difference in years of schooling or in the cultural level of the homes was very marked. A big difference of educational and cultural environment does not, however, guarantee a corresponding difference between the I.Q.’s of the twins. In one pair the difference in schooling amounted to ten years, plus four years of musical training--but the difference in I.Q. was only 12 points. One may conclude that certain hereditary types are much more amenable that others to modification of the intelligence by the environment.
With respect to the commoner mental diseases there is somewhat more variability between one-egg twins. For schizophrenia, manic-depressive psychosis, and epilepsy the concordance of one-egg twins is about 68 per cent in each case; whereas for two-egg twins it is about 15 per cent. A consideration of epilepsy is particularly instructive, because it has been found that one-egg twins it is about 15 per cent. A consideration of epilepsy is particularly instructive, because it has been found that one-egg twins, one of whom is epileptic, are always alike in possessing the same sort of abnormal electrical brain waves. Inheritance of the abnormal brain waves is dominant and depends upon a single gene; but the epileptic seizers, although restricted to persons with such brain waves, must depend upon unknown environmental factors as well. This is an example of a gene with one of the most important factors in determining the effectiveness of eugenic measures, for in certain individuals it the presence of the gene.
Even in regard to social traits and personality, the one-egg twins show a far greater degree of similarity that two-egg twins of the same sex. Five studies of criminality in twins have been made, with consistent results. Ina total of 104 pairs of one-egg twins and 113 pairs of two-egg twins, the concordance for the former amounted to 67 per cent, for the latter to 33 per cent. Such data do not mean, of course, that criminality, insanity, intelligence, or the like, are inherited as such, in a fixed, unalterable way. There is ample warrant, in all these studies, for concluding that past experience and present environment can suppress, diminish, or enhance the expression of such characteristics. But the investigations made on twins do show that similar hereditary natures generally provided the individuals are not subjected to radical differences in their environments. This was Galton’s original conclusion. However, it is clearly necessary to define the term “radical.”
A pair of blond one-egg twins may be temporarily separated, one kept indoors, the other sent for a vacation at the beach. In a few weeks one is sunburned and very much darker than his twin. This does not mean that environment determines complexion and that heredity has nothing to do with it. It means that for blond persons the amount of sunlight can constitute a “radical” difference in environment. Tet not all characteristics are affected by this “radical” difference of environment--only the complexion and such other traits as might be modified by light, for example, those that would be affected be a temporary change int he amount of vitamin D produced by the body. Only by careful experimentation can it be determined whether a specific difference in environment can affect a characteristic or not, and it must be determined separately for each characteristic. The effects of the environment a re inextricably interwoven in a person’s characteristics with that effects for the genes.
The primary concern of eugenics is with the frequency in the population of certain characteristics and of the specific genes that help to determine them. The study of evolutionary processes has made it clear that gene frequencies are changed by four principal factors: (1) mutation; (2) selection, natural or artificial; (3) chance; and (4) isolation or, conversely, migration. Other factors, such as the size of the population and the character of breeding, whether random or assortative, do not affect gene frequencies directly but have an important indirect influence by modifying the four chief factors. It has been calculated, for example, that in a population breeding quite at random with respect to the characteristics under consideration, the gene frequencies will remain in equilibrium, unchanged from generation to generation which is the Hardy [Weinberg principle. In other words. the hereditary nature of the species, the make-up of the population, will change only if some factor upses the equilibrium and favors one gene over another.
By mutation new sorts of genes come into existence, and without this there could be no long-continued process of evolutionary change, whether eugenic or otherwise. Mutations of a specific gene normally occur only very rarely. The mutation rates for several human genes have been estimated, and their average is about one in 50,000 per generation; that is, to take a specific example, in a population of 50,000 persons on person has a gene for hemophilia which was not inherited from either parent, but instead arose by mutation from a corresponding gene for normal blood clotting. It follows that, unless one could somehow prevent mutation, no measures can be successful in eradication a gene from the population. At nest, its frequency can be reduced to the levels of its rate mutation at a gene frequency of 1 in 50,000.
The frequency of mutation can be tremendously increased by X rays or other ionizing radiations that penetrate to the genes int he reproductive cells, by ultraviolet radiation, by heat, and by certain chemicals, such as mustard gas. It is therefore possible at the present time to produce vastly greater stores of new hereditary material upon which selection may be exercised, and this method may indeed help mankind to produce new forms of plants and animals more rapidly. For eugenics, this tool is too potent, since the vast majority of all mutations produce harmful consequences, and hardly one in 500 or 1,000 improves its possessor’s characteristics until in the course of generations they become homozygous, nevertheless we must avoid filling the human germ-plasm with an overload of harmful genes. Several lines of evidence make it likely that nearly everyone even now possesses at least one recessive lethal gene, that is, gene so harmful that were it homozygous it would destroy the life of its possessor at some stage during development. Other detrimental genes are probably at least thee times as numerous as the lethal genes. These genes can persist int the population because they are hidden. Each kind is prevented from becoming more common because of natural selection.
Natural selection works through differential viability or fertility; That is, possessors of certain inherited characteristics may less often that normal reach maturity and have an opportunity to reduce offspring; or they may, although mature, produce fewer offspring than normal because of celibacy or sterility. In either case, the responsible genes are diminished in frequency in the next generation. A lot of desirable genes are lost each time, too, for selection can act only on individuals, that is to say, on entire combinations of genes. It cannot pick out the solitary gene that is chief offender. The reassortment and recombination of genes in sexual reproduction constitute the saving factor here, and render it unlikely that the same unoffending genes will be lost each time a particular sore of detrimental gene is eliminated.
The rapidity with which the frequency of a gene can be reduced by selection depends upon the percentage of carriers who manifest the effects of that gene. A full dominate, for example, with a fitness only half normal (i.e., being passed on to the next generation only half as often as it would be if normal), would in twenty generations, or about five hundred tears, be reduced to one millionth of its original frequency. It would almost certainly reach the level where it would be maintained by fresh mutation before this. As a consequence, any particular harmful dominant trait is already, because of natural selection, very rare. It is of no eugenic consequence to try to deal with them. A lowered penetrance, however, will slow up the elimination of a dominant gene, and so too will lateness of expression in life. Huntington’s chorea, for example, is the result of a simple dominant gene It must be regarded as a very unfortunate nervous affliction, yet because the average age of onset is thirty-five years, viability and fertility do not appear to be affected by it at all. On the other hand, a recessive with a fitness of one half would in twenty generations be reduced in gene frequency only by about 40 per cent. What is more, the amount of reduction declines in each succeeding generation, as an ever larger proportion of possessors becomes heterozygous. The frequency of a common recessive gene might therefore be reduced very quickly; but the reduction in frequency of a gene already rare is almost imperceptible. Now, because natural selection has already been at work for ages past, no gene very detrimental or harmful gene is already rare in frequency and maintained in equilibrium between mutation and selection. Sex-linked recessives such as hemophilia fall in this respect between simple dominate genes and ordinary recessive genes. The combinations of genes which determine complex traits such as intelligence are even more slowly affected by selection.
Chance changes in gene frequencies and also the effects of isolation are not of as great eugenic significance in modern times as formerly, for they are marked detrimental gene may become established by chance, or a beneficial gene be eliminated. Also, in a small population those who marry. This inbreeding does not of itself change the open by increasing the proportion of homozygous persons, and that allows selection to be exercised upon them. If a line is free of harmful recessive genes, then inbreeding will do no harm; Cleopatra, for example, came of a number of genes, so that the effect of inbreeding is in general to increase the number of afflicted persons in the population. Selection can then exert a greater pressure on the relevant gene frequency. Actually, since medieval times, the trend has been merging to make large ones, and migrations of tremendous magnitude have produced human milting pots the world around. This has had the effect of reducing a greater proportion of the recessive genes to the heterozygous condition. They have disappeared from view and from exposure to selection, and can now increase under cover to a much higher frequency, until such time as by random mating homozygous persons are produced and selection again becomes active. THis may take thousand or tens of thousands of years. Meanwhile, it is important to realized what a disastrous increase in the proportion of hereditarily afflicted persons would result if our present populations ere for any reason--say, as the aftermath of another world war--to be broken up again into small units.
By surrounding itself with a social environment, mankind has unwittingly modified the rigor of natural selection int many respects. The price we must pay, in the end, for the mercies of medical care and surgical aid is the dysgenic increase in the frequencies of certain detrimental genes the effects of which we have learned how to ameliorate. Thousands upon thousands of diabetics who in a former day would have died early in life are now saved by insulin to live relatively normal lives, and or course, to pass on the genes responsible for their diabetes to their descendants. Myopia is no longer a grave handicap in life; hearing aids alleviate certain types of deafness. Probably no one would have it otherwise. Yet the vision of a future population composed extensively of persons who have to wear both glasses and hearing aids, and must start the day by inserting false teeth and taking an insulin injection, in none too pleasant. To say the least, medical science is steadily increasing to load it must carry.
Another instance of the unconscious direction of human evolution lies in the differential reproduction of economic and cultural groups. The differential reproduction of the several races may by ignored here, for there is no valid evidence that the known hereditary differences between them alter viability or fertility, or affect any eugenic desideratum, such as intelligence, There is little doubt that there is some cultural levels, in such countries as Great Britain and the United States. It is also well established that in the same countries the reproductive rate varies inversely with income. The result, theoretically, must be a decrease in frequency of these genes contributing to high intelligence, although the decrease might be slow. A tentative estimate by a British psychologist, Sir Cyril Burt, puts the decline in England at 1.5 or 2 IQ points per generation, which, if real, will in time have effects too grave to be ignored.
Eugenic Practices. The various measures of negative and positive eugenics may now be considered. The former comprise four methods, all of which are actually in operation in certain states or countries.
Segregation. That most widely used is the the segregation of males and females in separate institutions, such as prisons, mental hospitals, or other “homes.” To the extent to which it can be applied, this measure is very effective in preventing propagation. However, most social institutions of these kinds are today regarded as having a curative function rather that one of permanent incarceration and care; so that eventually a large proportion of the inmates of these institutions are released and are again at liberty to reproduce. To take care of the feebleminded alone in such institutions would moreover require an enormous increase in the humber of institutions and amount of care beyond what is at present available, since it is estimated that about 2 per cent of the population, or about 3,600,000 persons in the United States are feebleminded.
Sterilization. A second method is that of sterilization. This is also highly effective for the purpose, but has the drawback that no way of producing only temporary sterilization has been discovered. The surgical methods consist of ligating or cutting the sexual ducts, either oviducts or vasa deferentia. The methods thus prevents reproduction without interfering with the hormonal secretions of the ovaries or testes and so causing changes in the sexual characteristics and emotions, as does castration. In the United States, twenty-eight states have laws for the sterilization of the hopelessly insane or the feebleminded, but application varies greatly. Twelve states (California, Georgia, Indiana, Iowa, Kansas, Michigan, Minnesota, North Carolina, North Dakota, Oregon, Virginia, and Wisconsin) have a record of more than 1,000 sterilizations each, California being far in the lead with 20,041. The total (through Dec. 31, 1960) amounts to 62,162, of whom about half were mentally ill and half mentally deficient. (Statistics provided by the Human Betterment Association of America, Inc.) It is estimated that by sterilization and segregation the amount of mental defect and disease could be reduced perhaps 15 per cent, or from 2 per cent of the population to 1.7 per cent.
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