How do the peppered moths support the theory of natural selection?

One of those that caught my attention was the evidence of peppered moths changing their color from light to dark due to industrial pollution. This supposedly shows how natural selection can change a species into another type, and eminent scientists have emphasized the importance of this supposed proof of evolution.

Professor John Maynard Smith stated: "We should expect to find the most rapid evolutionary changes in populations suddenly exposed to new conditions. It is therefore natural that one of the most striking changes which has been observed in a wild population . . . is the phenomenon of 'industrial melanism,' the appearance and spread of dark forms of a number of species of moths" (The Theory of Evolution, 1966, p. 137).