Abstract
DR. WILHELMINE E. KEY has made (Carnegie Institution, Washington, Publication 296, 1920, pp. 102) a careful study of differential mating in a Pennsylvania family. The study comprises 1822 in dividuals, nearly half of whom are in the direct line of descent from two pairs of German immigrants of more than a century ago. The remainder were considered in connection with the strains into which the descendants of these couples married. The research began with four young people, patients at the Institution for the Feeble-minded of Western Pennsylvania, and was followed into intricate networks of stocks. Some of the general results may be outlined. (1) The behaviour in inheritance of such qualities as far-sightedness, perseverance, and push indicates that the occurrence of these traits is due to a segregation of their determiners. (2) There was a decided decrease in fecundity in all lines, but not more marked in the socially inefficient than in the efficient. On the other hand, the survival ratios increase for the successive generations of the efficient lines, while they decrease for the inefficient lines, thus illustrating Nature's method of eliminating the unfit. (3) In migration the more efficient push into new areas, the less efficient tend to settle down. (4) The reactions of the degenerate members show that the variations in efficiency are due not to adverse conditions, or to isolation, or to lack of opportunity, but to native inability and to the mating of defective with defective. (5) Individual immigrants of high potentiality tend to marry with the better native stocks, while those of low potentiality gravitate towards inferior native stocks. The whole history emphasises the usefulness (a) of segregating the markedly defective, (b) of some colonisation scheme, together with sterilisation, for certain types of the socially unfit, and (c) of some expert board of control with authority to prohibit marriages of a cacogenic sort. There is danger in ameliorative methods which allow the markedly unfit to multiply and counteract natural agencies for the selection of fit strains. More positively, public opinion requires to be educated towards a keener realisation of the possibilities of establishing strong strains of efficient citizens.
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Heredity and Social Fitness. Nature 106, 360–361 (1920). https://doi.org/10.1038/106360b0
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DOI: https://doi.org/10.1038/106360b0