Charles Darwin closely studied 13 species of finches, which were endemic to the Galapagos Islands. These birds formed the rudiments of Darwin's famous "Theory of Evolution by Natural Selection."
In 1831, Charles Darwin became the naturalist aboard the HMS Beagle, which was bound for a five year exploratory charting of the South Pacific region. It was on this voyage that he began his study of the finches. He observed that the birds were visually different, identifying that the patterns of their beaks varied in size and shape. He determined that the beak variations were linked to differing diets and, in turn, to available food sources. Darwin rationalized that the birds must have evolved from a common ancestor, providing the basis for his theories about evolution. Throughout his later career, Darwin went on to study other animals including pigeons and earthworms.