Prior to the Industrial Revolution, the majority of the population in England consisted of the light colored variation. The dark colored moth became the dominant variation by the end of the 20th century and remained so for almost 100 years. Today, the light colored variation is dominant again. What is the best explanation for this?
Dark colored moths survived better in the Industrial Revolution because their dark color helped them camouflage in soot. When the industrial revolution ended there wasn't as much soot, so the light colored moths now had a better chance of survival.
