Guinea Pigs

These results are the fundamental laws discovered by Mendel. But the results are not always as clear as in the case of the Andalusian fowl. In that case the hybrids were not like either parent, but were a new color, blue, so that they were labeled at once and recognizable as hybrids—but this is not generally the case. Take, for instance, guinea pigs. What will be the result of mating an “albino” white with a black guinea pig? Quite exactly the same principle applies as in the case of the Andalusian fowl, but the principle is not as clear to see. All the offspring are hybrid, but they will not be blue: they will be black. They will look like the black parent, but they are different. The black color predominates; i.e., black is “dominant” over white, while the white recedes out of sight, or is “recessive.” This hybrid black guinea pig is like the hybrid blue Andalusian fowl. It is a hybrid, a combination of white and black, but in the guinea pig the black covers up the white so that nothing in the color reveals the fact that it is a hybrid. Now if the hybrid black offspring of these black and white guinea pigs mate with each other, the result will follow exactly the same Mendelian law as applied to the Andalusian fowl. But this will not be so clear, because now we have two kinds of black instead of a black and a blue. One child in four will be pure bred black like the grandparent and two out of the four will be hybrid black. So to the eye we shall simply have, out of four children, one white and three black. But those three black are not all alike. One is a thoroughbred and two are half-breeds.

But how then are we to distinguish between the one pure bred black, the thoroughbred, and the two blacks that are hybrids so that we can be sure which is which? The only way they can be distinguished is to wait to see what their offspring will be in the next succeeding generations.

The one that is a thoroughbred will behave like a thoroughbred. For instance, if mated with white they will have nothing but black children. But if one that is hybrid black mate with one that is white, only half of the children will be white; these white children reveal the fact that their black parent was a half breed. Then we can put a tag on that black parent. If proper tags are put on the blacks so as to distinguish between the pure-blooded and the half-blooded—say a blue tag on the hybrids and a black on the thoroughbreds—we shall get exactly the same results as described in the case of the Andalusian fowl, in the six cases mentioned. The same principles apply to qualities of the guinea pigs other than color. Thus, if a long-haired guinea pig mates with a short-haired guinea pig, all the offspring will be short-haired, because short hair is dominant over long hair. Again, if a smooth-coated guinea pig mates with a rough-coated one, the result will be rough coated, because a rough coat is dominant over a smooth coat.

“Thoroughbred” Humans

The same principles undoubtedly apply to the human race, although as yet only a few traits have been carefully studied. Eye color is one of these. Imagine a marriage of a thoroughbred, black-eyed Italian with a thoroughbred, blue-eyed Irish. What will be the result? All the children will be black-eyed, black being dominant over blue; but these black eyes are not the genuine article that the Italian parent possessed. They are a blend, and it is only because the black element dominates over or conceals the blue element that we can not see on the surface that there is any blue there. But it may come out in the next generation; for, if these half-blooded individuals marry among themselves one-quarter of their children on the average will be blue-eyed. The other three-quarters will be black-eyed, but only one-quarter will be “really and truly” black-eyed, i.e., black-eyed like the Italian. The remaining half are hybrid black, like the parents. It is only a sort of imitation black so to speak.

The appearance of blue eyes in the second generation is the long observed but formerly mysterious “atavism,” or reversion to the grandparent.

Suppose the children of an Italian and an Irish parent intermarry with pure bred Italians. We immediately know what will be the result. All the children will be black-eyed, but among a large number only half will be thoroughbred black-eyed. The other half will be “imitation” black-eyed. The case is just like the mating of hybrid black guinea pigs with thoroughbred black guinea pigs, or of the blue fowl with the black. Similarly, if the Irish-Italian hybrids marry with pure Irish, half the offspring will be blue-eyed and half will be hybrid black-eyed.

Dominants and Recessives

Black eyes are “dominant” over blue eyes because the black color is due to a pigment, while the blue color is due to the absence of this pigment. In general a quality which is due to the presence of some positive element is dominant over a quality due to the absence of that element. A child inheriting from a blue-eyed person simply draws a blank from that side in the lottery.

In order to understand how these principles of Mendel apply in any given case we need first to know what traits are “dominant” and what are “recessive.”

Among traits known to be “dominant” are, besides pigmentation of the eye, certain peculiarities of the skeleton, such as short-fingeredness (two phalanges only on each digit), Huntington’s chorea, presenile cataract, congenital thickening of the skin, early absence of hair, diabetes insipidus, stationary night-blindness, liability to periodic outbreak of temper, etc.

Among traits known to be “recessive” are albinism (or lack of pigmentation), a certain degenerative disease of the eye, deafmutism, imbecility, insanity of certain types, certain nervous diseases; also mental traits, such as musical ability.

Suppose now that a normal or “strong-minded” person, if we may use that term as distinct from feeble-minded, marries a feeble-minded person. Assuming that the “strong-minded” person is a “thoroughbred” all of the children will be apparently normal. None will be feeble-minded. “Strong-mindedness” is dominant over weak-mindedness. Yet all these children that seem to be perfectly normal lack something in their bodies. This deficiency is simply covered up but can crop out in later generations. If two of these hybrids between the weak-minded and the strong-minded marry each other, one-quarter of the children will be feeble-minded, one-quarter thoroughbred strong-minded and the remaining half, though apparently strong-minded, will carry the taint in them just as their parents did. They are half-breeds. On the other hand, if two feeble-minded people marry, all of the children will be feeble-minded. Certainly we can and ought to forbid and prevent such marriages.

But feeble-mindedness is a recessive quality, so that if the feeble-minded marry only with normal individuals, the feeble-mindedness does not blight the next generation, and if these apparently normal children of such marriages take pains to marry only really normal individuals, avoiding not only the feeble-minded but even those like themselves who have feeble-mindedness on one side of their family tree, there will be no feeble-mindedness cropping out in future generations.

Instances of Eugenic Improvement

But not all human abnormalities are recessive. Thus Huntington’s chorea is dominant, so that every child of the unfortunate victim of this malady will contract it when it reaches the right age. Marriages of such people should, therefore, never be allowed, even with normal individuals.

But when we propose to restrict marriages or mating of those unfit to marry, people are apt to say, “That is a dream. It can’t be done.” But it can be done and it has been done. Every one has heard of the cretins in Switzerland. They are a kind of idiot who are short in stature and afflicted in all cases with goitre in the neck. Of course, many people have goitre who are not cretins, but there is no cretin who has not goitre. These cretins are peculiarly a feeble-minded people. They are common still in many towns of Switzerland; they are loathsome objects, helpless as children, with silly smiles, unable to take care of themselves in even the simplest toilet ways, and have to be looked after like domestic animals, or even more closely.

A gentleman very much interested in Eugenics visited Aosta, in Italy, just outside of Switzerland, once in 1900 and again in 1910. In 1900 he found many of these creatures among the beggars in the streets, in the asylums, in the home, in the orphan asylum—everywhere he ran across these awful apologies for human beings. But in 1910 he found only one! What had happened? Simply that a few resolute intelligent reformers had changed the entire situation. An isolation institution, or rather two institutions, one for the men and the other for the women, were established. In these the best care of the inmates was taken as long as they lived, and they do not live long. But pains were taken to see that by no possibility could marriage or mating of those people take place. They forfeited any such rights in return for the care that they received from the State.

Thus is it possible to apply the laws of heredity as laid down by Mendel in a thoroughly practical way and to get results immediately in one short generation. It seems, and it is, a colossal task to change average human nature one iota. Yet in the light of modern eugenics we could make a new human race in a hundred years if only people in positions of power and influence would wake up to the paramount importance of what eugenics means. And this could be done quietly and simply without violence to existing ideas of what is right and proper. It could be done by segregation of the sexes for defectives, feeble-minded, idiots, epileptics, insane, etc. By this kind of isolation we can save the blood-stream of our race from a tremendous amount of needless contamination.

And it is being done. The growing tendency to put defectives in institutions, though originally with no such object, will reduce the transmission of defects, especially when it is recognized that the sexes must be separated and that the inmates should be kept at the institution through the reproductive period of life.

Educational Influence

It is inconceivable that the average individual will deliberately and consciously make his calculations regarding the character of possible offspring before he allows himself to fall in love to the point of desiring marriage. Yet unconsciously an educational influence on love and on marriage selection has been operating through centuries. The sick, the feeble-minded, the immoral, and members of their families, have at all times been socially handicapped, and have always been the first to be eliminated in marriage selection. And it is conceivable that this already developed wisdom in mate-choosing can easily be augmented by a further knowledge of heredity which is now available. It unconsciously favorably modifies the individual taste.

Certain races of men, without consciousness of their action, have varied in the character of their choices (sex selection) in such a way as to bring about varied conditions in their races, with respect to resistance to disease, of mental capacity and to moral quality. The Mongolian differs from the Hebrew, the Anglo-Saxon differs from the African.

It depends largely upon the action of those now upon the earth, who are now making their choices of marriage, as to whether the races of the future shall be physical, mental or moral weaklings, or whether they shall be physically brave and hardy, mentally broad and profound, and morally sterling.

Summary

To summarize: There are three main lines along which eugenic improvement of the race may be attained:

(1) Education of all people on the inheritability of traits; (2) segregation of defectives so that they may not mingle their family traits with those on sound lines; (3) sterilization of certain gross and hopeless defectives, to preclude the propagation of their type.

There would seem to be great need of State Eugenic Boards, to correlate and to promote these activities, in the interests of the future population, and to give expert advice as to how to legislate wisely, and individual advice as to how to mate wisely. The latter function now falls entirely upon the Eugenics Record Office at Cold Spring Harbor, where the work is being carried on with great efficiency with the funds at command.

REFERENCES

[57] Darbishire, A. D.: Breeding and the Mendelian Discovery, Cassell & Company, Ltd., London, New York, Toronto and Melbourne, 1911.

[58] Davenport, Chas. B.: Heredity in Relation to Eugenics, Henry Holt & Company, New York, 1911.

[59] Dugdale, Robert L.: The Jukes, G. P. Putnam’s Sons, New York and London, 1910.

[60] Galton, Francis: Hereditary Genius, D. Appleton & Company, New York, 1870.

[61] Goddard, Henry H.: The Kallikak Family, The Macmillan Company, New York, 1912.

[62] Kellicott, William E.: The Social Direction of Human Evolution, D. Appleton & Company, New York and London, 1911.

[63] Huth, Alfred Henry: Marriage of Near Kin, Longmans, Green & Company, London, 1887.

[64] Darwin, Charles: The Descent of Man, Thomas Y. Crowell & Company, New York, 1874.

For further bibliographic lists, see bulletins entitled “Books and Journals,” and “Publications” issued by the Eugenics Record Office, Cold Spring Harbor, N. Y.

INDEX

A B C D E F G H I J K L M
N O P Q R S T U V W X Y Z