An exploration of the scientific phenomenon known as "adaptive radiation", the way in which a small founding group of a plant or animal species can give rise to a number of new species, and the way in which a new environment encourages this proliferation - Darwin's "natural selection" in action. Oceanic islands are the best places to see the process at work, and the Galapagos provide the best of all demonstrations. The program looks at the many forms of animal and plant life in the islands, with particular attention to the evolution of the species unique to them.