section_path: Life on islands/Darwin, the Galápagos, and natural selection
section_name: Darwin, the Galápagos, and natural selection
paragraph_text: Darwin, the Galápagos, and natural selection
  
  Charles Darwin formulated the theory of natural selection through the study of island ecology. The species he observed on the Galápagos Islands, including tanager birds, contributed to his understanding of how evolution works. He first traveled to the islands as a naturalist on the HMS Beagle in 1835, as part of a five-year circumnavigation of Earth. He wrote that "the different islands to a considerable extent are inhabited by a different set of beings". Through the study of the finches and other animals he realized that organisms survive by changing to adapt to their habitat. It would be over twenty years before he published his theories in On the Origin of Species.