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i E E EB W E JUL . 9 2010 uj THE GEORGE E BROWN, JR- LBRARY NATIONAL ACADEMY OF SCIENCES M E M O I R DPON TBE FORMATION OF A DEAF VARIETY OF THE HDMAN RACE. AIEXANDEB GBAEAM BELL 99 A â B E L L 1
UPON THE FORMATION OF A DEAF VARIETY OF THE HUMAN RACE. A PAPER PRESENTED TO THE NATIONAL AOADEMT OF SOIENOES AT NEW HAVEN, NOVEMBER 13, 1883 INTRODUCTORY REMARKS. The influence of selection in modify mg oar breeds of domestic animals is most marked, and it, is reasonable to suppose that if we could apply selection to the human race we could also produce modifications or varieties of men, Jiut how can we ascertain the susceptibility of the human race to variation produced by selec- tion? W e cannot dictate to men and women whom they shall marry, and natural selection no longer influences mankind to any great extent. We can see around us everywhere evidences of the transmission by heredity of characteristics, both desirable and undesirable, but at first sight no general selective influence appears to be at work to bring about the union in marriage of persons possessing the same congenital peculiarities. On the contrary, sexual attraction often appears to operate after the manner of magnetical attrac- tionâ" unlike poles attract, like poles repel." Strong, vigorous, and robust men naturally feel tenderness for weak, delicate, and fragile women, and are generally repelled by physical strength and mascnhne traits in one of the opposite sex. Even in such characteristics as the color of the hair and eyes, it often appears that unlikes attract. Certain diseases are known to be liable to transmission by heredity. But we do not find epi- leptics marrying epileptics, or consumptives knowingly marrying consumptives. Even though persons afflicted with the same hereditary disease were to intermarry for a number of successive generations, it is doubtful whether any permanent variety of the race could be formed in this way, for the increased tendency to disease mhented by the offspring would probably cause a greater tendency to premature death and ultimately occasion the extinction of the variety. On the other hand, it is reasonable to suppose that the continuous intermarriage of persons possessing congenital defects not associated with diminished vitality or vigor of constitution would result after a number of generations m the production of a vigorous but defective vanety of the race. F o r instance, the absence of coloring matter from the skm and hair is a defect occasionally found among human beings, and we may learn from the success of attempts to propagate Albinism among animals, that we would probably produce a pink-eyed, white-haired variety of the human race by causing Albinos to marry one another; but this is only speculation. W e cannot control the marriages of men as we can the breeding of animals, and at first sight there seems to be no way of ascertaining how far human beings are susceptible of variation by selection. 3
4 MEMOIRS OP T H E NATIONAL A C A D E M Y O F S C I E N C E S . Such a conclusion, however, would be mcorrecfc; and I desire to direct attention to the fact that in this country deaf-mutes marry deaf-mutes. A n examination of the records of some of our institutions for the deaf and dumb reveals the fact that such marriages are not the exception, but the rule. For the last fifty years there has been some selective influence at work which has caused, and is still causing, the continuous selection of the deaf by the deaf in marriage. I f the laws of heredity that are known to hold in the case of animals also apply to man, the intermarriage of congenital deaf-mutes through a number of successive generations should'result in the'formation of a deaf variety of the human race. On the other hand, if it can be shown that congenitally deaf persons marry one another without any greater liability to the production of deaf ofispring than is to be found among the people at large, then it will be evident that we cannot safely apply to man the deductions that have been drawn from experiments upon animals. There are good grounds for the belief that a thorough investigation of the marriages oi the deaf and the influence of these marriages upon the offspring will afford a solution of the problem, " To what extent is the human race susceptible of variation by selection?" Although the statistics I have been able to collect are very incomplete, I have ventured to bring the subject to the attention of the Academy, in the hope that the publication of the results so far obtained may lead to the completion of the statistics.
