Charles Darwin was fascinated by the finches on the Galapagos Islands. He noticed that the finches with long, narrow beaks were able to eat , while other finches that had shorter and thicker beaks were able to crush and eat . Darwin suggested that these different species of finches must have from a single species of finch that came to the islands a long time ago. When the single species of finch experienced , some of the small changes in beak shape and size may have turned into an that would help that finch and pass on the trait to its offspring.