In 1896, J.W. Tutt noted that typicals were well camouflaged against the light-colored lichens that grow on tree trunks in unpolluted woodlands; but in woodlands where industrial pollution has killed the lichens, exposing the bark and darkening the tree trunks, melanics are better camouflaged. Since conspicuous moths are more likely to be eaten by predatory birds, Tutt attributed the increase in the proportion of melanic forms to natural selection.
In the 1950s, Bernard Kettlewell tested the idea experimentally by marking several hundred peppered moths (typicals as well as melanics) and releasing them onto tree trunks in a polluted woodland near Birmingham, England. Kettlewell observed through binoculars that melanics seemed less conspicuous than typicals, and that birds took conspicuous moths more readily than inconspicuous ones. That night he recaptured 27.5 percent of the melanics, but only 13.0 percent of the typicals, suggesting that a much higher proportion of melanics had survived ...
