BACK TO BIOLOGY

Evening Post, Volume CVI, Issue 52, 10 September 1928, Page 10

BACK TO BIOLOGY

MENDELISM AND MAN WARNINGS OF SCIENCE (By P. Fraser, M.P.) 11. The material with which biologists have experimented for years arc peas, evening primroses, pigeons, white rats, guinea pigs, poultry, rabbits, silk moths, fruit flies, and domestic animals of various kinds. The deductions drawn from the study of the controlled breeding of animals and plants have been formulated in the Mendelian laws, the theory of unit characters, and that of the continuity of the germ-plasm. How far do these studies and theories get us in regard to mankind. Dr. 11. S. Jennings, Professor of Zoology, and Director of the Zoological Laboratory at the John Hopkins University, in his fascinating little book, "Prometheus or Biology and the Advancement of Man," warns us against the fallacy of placing too great reliance on experiments with animals as a basis for. the breeding of the human race. He says:— "When the biologist, from his knowledge of other organisms, is tempted to dogmatise concerning the possibilities of human development let him first ask himself: 'How correctly could I predict the behaviour and social organisation of ants from a knowledge of the natural history of the oyster?' Man differs from oth-. or organisms in these respects certainly as much as the ant does from the oyster; for these distinctive aspects of his biology only the study of man himself is relevant." Professor J. Arthur Thompson, in his great work on "Heredity," says:— "We have little faith in a biology which does not frankly admit that .an organism is a new synthesis when compared with inanimate systems, and we have equally little in a sociology which does not consistently recognise that a human societary unit, however simple,- is also a now synthesis as compared with the beasts of the field —a unity with a distinctive mode of behaviour, with a whole fliat is more than the sum of its parts; in short, with a life and mind oi: its own." EUGENISTS' CLAIMS. What are the Eugenists after? What do they propose should be done? What do they claim to know? What do they think they can do? Mr. Albert Wiggam, a leading American Eugenist, claims that eugenics is "Simply the projection of the Golden" Rule down the stream of protoplasm." In a more coherent moment he says that eugenics mean "the study and guidance of all those agencies that are within social control, which will improve or impair the inborn qualities of future generations.". Mr. Herbert W. Walter, in his book "Genetics," writes: — "A negative way to bring out the better blood in the world'is to follow the clarion call of Davenport and 'dry up tho streams of defective and degenerate protoplasm.' This may bo partially accomplished, at least in America, by employing the following agencies: Control of immigration, more discriminating marriage laws, a quickened eugenic- sentiment, sexual segregation of defectives, and, finally, drastic measures of sterilisation when necessary." . „ Mr. Walter informs us .th.it if sterilisation laws could bo enforced, "Less than four generations would eliminate nine-tenths of the crime, insanity, and sickness of the present generation in our land. Asylums, prisons, and hospitals would decrease and the problems of the unemployed, .'tho indigent, old, and the hopelessly degenerate would cease to trouble civilisation." The language is almost identical with that used by some exuberant supporters of the more drastic provisions of the Mental Defectives Bill. According to them the task of legislating, for the germ plasm is all plain and easy sailing on a perfectly charted sea. The remedy is also so simple—just a little law to provido for a minor operation, vuscetomy, on the male, and a more serious major operation, salpingectoiny, in the case of the female, and, presto, in four generations or so practically all, about nine-tenths, of our insane, mental defectives, criminals, prostitutes, and paupers, will have disappeared. Clearly in the mind of the true-blue eugenist sterilisation is the legislative goal. Anything short of that, is an insipid palliative only to be tolerated until the ideal is achieved. LAWS OF HEREDITY. "What do the biologists say to all those extravagant claims? What knowledge is possessed of the operation of heredity in mankind? What arc the known laws of heredity and how far do they apply to man? In 1866 Gregor Johanu Mendel, Abbot of Brunn, published the results of his experiments in controlling the breeding of peas. His essay, was forgotten until 1900, when it was rediscovered independently by three different botanists, De Vries, Correns, and Tschermak. Mendel's laws tell all that is known about the proportions in which certain characteristics of parents appear in children. Briefly, Mendel formulated the general law that when an individual with a dominant character is mated with an individual with a corresponding recessivo character the offspring of the first generation will all show the dominant character, while in the next generation dominants will appear in tho proportion of three to one. If a tall dominant pea is crossed with a dwarf recessivo the offspring will all be tall but with the potentiality of producing dwarf plants. In tho next generation, produced by self-fertilising, out of every four plants one will bo tall with tho capability of producing only tall peas as offspring; one will be dwarf with the capability of producing only dwarf peas; and two will bo tall but copablo of producing both tall and dwarf peas in the proportion of three to one, and so on ad infinitum. In the above instance it would be held that tallness is a unit and that its behaviour in inheritance is independent of all other units. Thi~ is called the theory of independent unit characters. The Eugenist "Field-workers" in America are always keen on the track of the elusive "unit Characters" endeavouring to hunt them down in unfortunate people in very much the same way as the bootlegger is hunted. It complicates matters somewhat when wo find Professor "W. E. Castle, of Harvard, stating that in spite of tho fact that many students of Genetics regard unit characters as unchangeable and as impossible of modification as aro the atoms, ho considers that "Tho fact is unmistakeablo that unit characters are subject to quantitative variation," and are ■" modifiable as well as recoinbinablo," and that those Mendolians who think otherwise do so because they have not studied the question close enough. It is even more disconcerting to the dogmatic eugenist when we have Professor Jennings roundly declaring that: Clearly it is not necessary to have a characteristic merely because one"inherits" it. Or more properly,

characteristics aro not inherited at all; what ono inherits is certain material that under certain conditions will produce a particular characteristic; if those conditions are not supplied, some other characteristic is produced. What human characters have been shown, or are claimed to have been shown, to behave like tallness and dwarfness in peas. The following list taken from "The New Age of Faith," by John Langdon-Davies, is the most complete I have been able to find, and is corroborated by all the leading authorities which I have consulted:— Eyo colour: Is the only normal human character shown to follow jMendelian laws. The type of eye in which pigment is present on the front of the iris is dominant; absence of such pigment is recessive; or in other words brown eyes are dominant ■ to blue eyes, and if a man -with pure brown eyes marries a woman with pure blue eyes all their children will • have brown eyes and their grandchildren brown eyes in tho proportion of three to one. Urachydactyly: Or usually short and stumpy lingers. Cataract: When this eye' is congenital and not acquired. Tylosis palmaris et plantaris: A thickening of the skin on the palms of the hands and the soles of the feet. Epidermolysis Bullosa: A skin condition which makes one blister easily. Xanthoma, or yellow patches on the skin. Multiple Tcleangicctasis, or spot* on the skin. Monolithrix: A nadose condition of tho hair. Hypotrichosis congenita familiaris, or premature baldness appearing in infancy. Porokeratosis: A curious disease in which a raised horny ridge appears on the skin, spreading centrifugally, leaving behind it a patch in which the constituents of the skin undergo a partial atrophy. Enlarged spleen. Night blindness. Distichiasis: A development of eyelashes in place of glands on the inside of the eyelids. Ptosis, or drooping of the upper lip. Coloboma: A congenital defect in the iris of the eye. Ectopia lentis: Another eye trouble. Haemophila, or easy bleeding. Colour blindness. ,To this strange--list Major Hurst would add musical ability as a recessive, and some cases of feeblemindedness seem to follow the same law." The above list shows how relatively unimportant to tho sociologist are the positively known human traits which follow Mendelian laws. In regard to mental deficiency, Professor T. H. Morgan, one of the world's greatest geneticists, says:—"Feeble-1 mindedness . . . has been said to be inhorited as a Mendelian recessivo, but until some more satisfactory definition can be given as to where feeblemindedness begins and ends, how many and what internal physical defects may produce a general condition of this sort, and until it. has been determined to what extent feeblemindedness is due to syphilis, it is extravagant to pretend to claim that there is a single Mendelian factor for this condition.'' Tho next article will deal with tho mystery of "Mutations," the function of the chromosomes, some results of hybridisation, and tho impossibility of even approximately accurate predictions concerning offspring.