MENDEL’S LAWS

Evening Star, Issue 21318, 24 January 1933, Page 10

MENDEL’S LAWS

RELATION TO HUMANITY TESTING HEEDED The creation of new races of men by the intensive study and application of Memlelian laws of heredity to human beings was urged before the International Congress of Genetics by Dr C. B. Davenport, of the Cold Spring Harbour Genetic Station of the Carnegie Institution of Washington, says the ‘ New York Times.’ Mendclian studies in man, Dr Davenport stated, offered an alluring field lor future investigation, not lor the deteimination of fundamental laws of genetics hut for the application of the laws to that species upon whom all progress in science depended. “ A more precise knowledge ot the inheritance of traits will contribute toward an insight into the consequence ot particular made selections and of race crossing,” Dr Davenport went on. “ As medical skill and State care ol defectives increases it is probable that the population will include more and more mutations or irregularities. It is also probable that through man’s capacity for adjustment, even under physical handicaps and harmful surroundings, more ot these mutations have been preserved than would be possible in a species less adaptable. “ When, some thirty-two years ago, Mendel's laws were rediscovered and his work became famous, one of the first questions was: Can the laws ho applied to man? For, if tho prediction of an average result could lie replaced by a, definite statement of the consequences of a particular mating, much would he gained. FIRST ATTEMPTS. “ The first steps to prove the application of these laws concerned the inheritance of eye colour, skin colour, hair form, and many skin diseases, and showed that the singling out of those characteristics was based, in most eases, on simple .Mondolian factors. Later students of heredity had difficulties because of complications in the Jaws or inheritance in man. Explaining the difficulties of testing Meiulolian theories in man, Dr Davenport continued ; “ The time which elapses between generations makes it difficult t.o get

precise first-hand information even about three generations. Small families make investigation more difficult, for it is almost impossible to apply the Mendelian formulas where there are only from one to three children. Many human traits depend on multiple factors, and if a trait is due to three or more genes, or character determines in the germ, it is practically impossible to prove the development of traits definitely. “ Another difficulty grows out of the sensitiveness of man to changes in his surroundings, as shown by human characters in their development. This probably, in part because human development is so prolonged, continuing for years as contrasted to that of the drosophia, or fruit fly, which takes place in less than ten da3’s. “ A hereditary lack in the development, of the thyroid gland may pass unnoticed in a section where iodine is plentiful, but this lack becomes apparent if the iodine in the water or food falls below a certain minimum. SHOULD BE TESTED. “ Although man is perhaps the worst species in which to study the laws of genetics, it is important that the principles established in other organisms should be tested in man. “ The inheritance of certain traits, especially mental traits, can be better studied in man than in another species, partly because of man’s familiarity with his bodily and mental variations and because of the opportunity to get his co-operation in their measurement.” Dr Davenport enumerated several strata among human beings in which ‘‘matings of similar instincts ”• occur, including naval families, “ whose social inter-relations are such that the .young men and women are brought early into contact.” “ Similarly, there is selective mating among biologists,” he added, '* partly because of the existence of summer marine laboratories, like that at Woodshole and Cold Spring Harbour, where tlie young people associate in informal fashion. “ Despite the unassorted mating obvious in most cases, there is a good deal of social stratification,” Dr Davenport continued. ” Thus the scholastic stratification, seen in the matings inside of college communities; the stratification among politicians and statesmen who sojourn long with their families in the legislative capital ; the stratification of artists, who tend to live in colonics; Hie stratification of the deaf who can converse only with other deaf who know the sign language; the stratification of exiled missionaries and of the farm and valley communities in this country, with their high incidence of f'ceblo-mimledness.

“ These stratifications, or castes, if you will, afford an opportunity for the study of selective matings, even in a species whose matings seem at first blush so uncontrolled as man’s.”