The Galapagos Islands are home to 14 species of finches; differing mainly on their beaks, which are adapted for specific diets.

1. The long beak of the cactus finch helps it tear and eat cactus flowers and pulp.

2. The warbler finch uses its narrow beak to grasp insects.

3. The large ground finch has a large beak adapted for cracking seeds.

Darwin hypothesized that the different birds evolved from a common ancestor: descent with modification.