The idea that the evolution of the human intellect is a perpetually progressive process by means of the constant use of the brain in the pursuits of increasing civilisation towards the eventual attainment of god-like perfection is one that appeals strongly to the popular fancy, and its corollary, that those who fail during long periods to make full use of their mental equipment in the ways of advancing civilisation must gradually lose a part, if not the whole, of their original talents, is commonly accepted as being warranted by the teaching of modern science.

But science, as a body, does not support the view that bodily characters and modifications acquired by an individual during his lifetime are transmissible to his offspring; in other words, science does not, as a body, accept the theory that the effects of use and disuse in the parent are inherited by his children.  Modern science does not, indeed, definitely foreclose discussion of the subject, but what it says is that the empirical issue is doubtful with a considerable balance against the supposed inheritance of acquired characters.

Very recently evidence has, indeed, been adduced to prove that “Initiative in animal evolution comes by stimulation, excitation and response in new conditions, and is followed by repetition of these phenomena until they result in structural modifications, transmitted and directed by selection and the law of genetics.”  The student who tenders this evidence is Dr. Walter Kidd[12] who claims that his observations of the growth of the hair of the harness-horse prove that the prolonged friction caused by the harness produces heritable effects in the pattern of the hairy coat of this animal.  It is admitted by this observer that such momentary and acute stimuli as are involved in the mutilation of the human body by boring holes in the ears, knocking out teeth, and by circumcision, which practices have been followed by so-called savages during long ages, seldom, if ever, lead to inherited characters, but he maintains that the effect of prolonged friction by the collar on the hair on the under side of the neck of the harness-horse has produced marks or patterns in the same place on certain young foals born by these horses.

These observations must, of course, be submitted to strict examination before science will pronounce its opinion.  Meanwhile I may be allowed to cite what Dr. Kidd calls an “undesigned experiment,” which to my mind goes far to prove that the effects of prolonged friction on the human body during many generations is not heritable.  The custom followed by many Bantu tribes of producing in their women an elongation of the genital parts by constant manipulation must have been practiced during very many generations, certainly much longer than the comparatively recent harnessing of horses in England, for we know how tenaciously primitive people cling to their old customs, generation after generation, for thousands of years, and yet no instance has ever been noticed by these people, who are very observant in these matters, of any sign of such an inherited characteristic in any of their female children.