What Evolution Is, and What It's Not

Evolution, in the sense of common descent, is not a theory of similarity. Linnaeus, Cuvier, and Agassiz knew all about similarity, yet they denied common descent. Evolution is a theory of transformation.

Here's an instructive parallel. Lead (Pb) and gold (Au) share many similarities: Au and Pb are metals. Au and Pb are dense, with very similar atomic masses. Au and Pb are highly ductile.

And so on. It doesn't take much to imagine that, with the right chemical methods, one could transform lea...