Learn how Bernard Kettlewell's study of peppered moths in industrial England provided compelling evidence for natural selection and evolutionary change.

The Fascinating Tale of Kettlewell's Moths: A Study in Evolution

In the mid-20th century, a British scientist named Bernard Kettlewell embarked on a groundbreaking journey to uncover the mysteries of natural selection, using the peppered moth as his subject. This captivating story took place in the industrial regions of England, where Kettlewell's experiments in the 1950s provided compelling evidence for Darwin's theory of evolution by natural selection. The reason behind this study was to understand how environmental changes, specifically industrial pollution, could drive evolutionary changes in species.

Kettlewell's research focused on the peppered moth, which comes in two color variations: a light, speckled form and a dark, or melanic, form. Before the Industrial Revolution, the light-colored moths were more common, as they blended in with the lichen-covered trees, making them less visible to predators. However, as industrial pollution darkened the trees with soot, the darker moths gained a survival advantage, as they were better camouflaged against the now-darkened bark.

Kettlewell conducted his experiments by releasing both light and dark moths in polluted and unpolluted woodlands and observing their predation rates. His findings were astonishing: in polluted areas, the dark moths had a higher survival rate, while in unpolluted areas, the light moths thrived. This demonstrated natural selection in action, as the moths' coloration directly influenced their survival based on the environmental conditions.

Kettlewell's work was pivotal in providing tangible evidence for the process of natural selection, a cornerstone of evolutionary biology. It highlighted the dynamic relationship between organisms and their environments, showing how species can adapt over time in response to changing conditions. This study not only advanced our understanding of evolution but also underscored the impact of human activities on the natural world, sparking further research into the effects of pollution and environmental change on biodiversity.