Thomas Hunt Morgan

A Critique of the Theory of Evolution Thomas Hunt Morgan

Book Excerpt: ...on to the order in which its members have appeared. Suppose that evolution "in the open" had taken place in the same way, by means of discontinuous variation. What value then would the evidence from comparative anatomy have in so far as it is based on a continuous series of variants of any organ?No one familiar with the entire evidence will doubt for a moment that these 125 races of Drosophila ampelophila belong to the same species and have had a common origin, for while they may differ mainly in one thing they are extremely alike in a hundred other things, and in the general relation of the parts to each other. It is in this sense that the evidence from comparative anatomy can be used I think as an argument for evolution. It is the resemblances that the animals or plants in any group have in common that is the basis for such a conclusion; it is not because we can arrange in a continuous series any particular variations. In other words, our inference concerning the common descen...