How do you understand Darwin's theory of evolution?

Answer 1

When Darwin visited the Galapagos he noted that the islands had very different climates but had similar birds. He recognised a species of finches common on the mainland but on each island they had different shaped beaks. Some had long pointed beaks to extract insects from their burrows.On another island the finches had grown massive short beaks that were able to crack nuts.

Taking a sample from each island he realised that they had all originally been from a single breeding pair which had probably been blown from the west coast of South America and had stayed.

This was a key discovery, birds with the wrong beak died, birds with a shorter beak could crack small nuts leaving bigger nuts for those birds that would evolve with a bigger beak. These birds still exist in the Natural History Museum and are known as the Galapagos Finches. Giant tortoises from each island have evolved different neck arches in their shells to cope with the local vegetation