The evidence that supports human influence on the populations of the peppered moth is centered around the impact of soot on pollution-sensitive lichens. During the Industrial Revolution in England, air pollution from coal smoke led to the deposition of soot on trees. This environmental change caused a significant reduction in the population of light-colored moths, which were more visible against the soot-darkened trees, and supported the survival of darker-colored moths. As a result, the proportion of dark moths in the population increased—a phenomenon known as industrial melanism.
The connection between soot, lichen, and the moth population is a clear example of how human activities, specifically industrial pollution, directly altered the environment in a way that influenced natural selection. As pollution levels began to decline due to cleaner air initiatives in the latter half of the 20th century, the lighter-colored moths began to increase again, further demonstrating the direct impact of human actions on the moth's population dynamics.