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Before the English Industrial Revolution of the late 18th and early 19th centuries the most common phenotypic color of the peppered moth was white with black speckles. However, that changed when the Industrial Revolution produced high levels of pollution. Due to the Industrial Revolution the trees blackened in urban regions, causing the original phenotype to stand out significantly more to predators. Natural selection then began favoring the rare dark peppered carbonaria moth in order for the species to camouflage and prevent attacks. The dark moth’s population expanded rapidly and by the 1950s vast amounts of England saw carbonaria frequencies rise above 90%. The once favorable white speckled phenotype quickly became mismatched in the new environment and since evolution did not have enough time to take its course, the white speckled coloring became disadvantageous.

However, in the late 1900s, the English made efforts to reduce air pollution, causing the trees to turn back to their normal shade. The change in color lead the dark skin phenotype to revert from beneficial to disadvantageous. Once again, the moth was not able to adapt fast enough to the changing environment and thus the carbonaria phenotype became mismatched. Since The trees’ return to their natural color caused the original phenotype to become advantageous again since it allowed the peppered moth to hide from predators.