<P> The evolution of the peppered moth is an evolutionary instance of directional colour change in the moth population as a consequence of air pollution during the Industrial Revolution . The frequency of dark - coloured moths increased at that time , an example of industrial melanism . Later , when pollution was reduced , the light - coloured form again predominated . Industrial melanism in the peppered moth was an early test of Charles Darwin 's natural selection in action , and remains as a classic example in the teaching of evolution . Sewall Wright described it as `` the clearest case in which a conspicuous evolutionary process has actually been observed . '' </P>
what caused natural selection among the peppered moths of manchester england
air pollution during the Industrial Revolution