Selection of the genetic basis for an acquired character

Abstract

THERE are so many examples of the adaptation of an animal to its environment which at first sight would appear to find their simplest explanation in the supposition that the effects of the environment have become inherited, that theories of this kind have continued to retain a following in spite of the lack of clear experimental evidence in their support. This following has been composed mainly of naturalists; experimentalists and geneticists have recently tended to adopt an attitude similar to that expressed by Dobzhansky1, who writes: "This question has been discussed almost ad nauseam in the old biological literature ... so that we may refrain from the discussion of it altogether". In dismissing the matter so cavalierly, Dobzhansky was explicitly referring to "direct adaptation", that is, the hypothesis that when the environment produces an alteration in the development of an animal, it simultaneously causes a change in its hereditary qualities such that the developmental alteration tends to be inherited. It has been usual, indeed, to consider this suggestion as the only possible alternative to the opposed view that environmental effects have no hereditary consequences, the phenomena of adaptation being solely due to the natural selection of chance variants. © 1952 Nature Publishing Group.