The fact of evolution is the backbone of biology, and biology is thus in the peculiar position of being a science founded on an unproved theory -is it then a science or a faith? Belief in the theory of evolution is thus exactly parallel to belief in special creation - both are concepts which believers know to be true but neither, up to the present, has been capable of proof.
The [peppered-moth] experiments show the effects of predation on the survival of the dark and of the normal forms of the Peppered Moth in a clean environment and in one polluted by smoke. The experiments beautifully demonstrate natural selection--or survival of the fittest--in action, but they do not show evolution in progress, for however the population may alter in their content of light, intermediate or dark forms, all the moths remain from beginning to end Biston Betularia.