Page:Popular Science Monthly Volume 76.djvu/421

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THE

POPULAR SCIENCE

MONTHLY


MAY, 1910




HEREDITY[1]

By Professor W. E. CASTLE

HARVARD UNIVERSITY

THE conservation movement now in progress has for its end to preserve for future generations of men the natural resources of the earth. But it goes without saying that the movement is useless unless there are to be future generations of men capable of utilizing those resources. Thoughtful persons are beginning to wonder whether this is assured. Man is the product of two sets of agencies which we summarize in the terms heredity and environment. The question has often been asked which of these is the more important, but with this we need not concern ourselves. Both are indispensable. Seed and soil combined assure a harvest, but if either is lacking no harvest can be expected.

The public is awakening to the importance of providing mankind with a proper environment through the agencies of sanitation, education and good government, and this is well. This assures a suitable soil in which a crop of healthy human beings may develop. But what of the seed? This question has not yet been seriously considered. Only in England has it been more than suggested. There Francis Galton and his associates in the eugenics movement have started an inquiry as to why it is that the average physical condition of the English nation is declining although more and more attention is constantly being given to improving the environment. Likewise in Germany statistics show a steadily declining proportion of the young men fit for military service. There is a suspicion in the minds of many, that these nations are producing the new generation of citizens chiefly from inferior family and racial stocks. If this is so the remedy is

  1. From a lecture delivered before Section F, American Association for the Advancement of Science, December 31, 1909.