Charles Darwin's life represented the essence of science. He was naturally curious and reflective and a keen observer who was always gathering evidence to explain the world around him. Even before Darwin stepped onto HMS Beagle, he was an experienced naturalist. He spent much of his early life outdoors observing nature and during college had many scientists as mentors who engaged him in long conversations about science.

But the voyage of the Beagle was the turning point in Darwin's life. It gave a breadth and depth to his experience that was invaluable to his later thinking. During the five-year journey of the Beagle (1831-1836), Darwin spent only 18 months at sea. The rest he spent ashore. His curiosity, coupled with his frequent bouts of seasickness, inspired him to take long expeditions exploring the natural history and geology of South America, the Galápagos Islands, Tahiti, and Australia. Darwin made careful observations and looked for patterns wherever he went. His key observations about the diversity and distribution of species spurred his thinking for the book that would revolutionize science: On the Origin of Species by Means of Natural Selection.

Darwin wrote letters to his mentors and sent his collections home throughout his journey. By the time Darwin stepped off the Beagle, he was already recognized by the scientific community for his expertise.

Upon Darwin's return, he spent eight years studying barnacles and believed that his in-depth knowledge in this one area sparked his thinking in others. During this time, Darwin began to develop his revolutionary theory of natural selection, which explained a mechanism for evolution. He carefully explored different lines of evidence, experimenting and gathering information to support his case for evolution.

One of Darwin's interests, pigeon breeding, played a significant role both in the development of his theory of natural selection and in the way he presented his argument in The Origin of Species. Darwin wanted to demonstrate that new species could be created from a common ancestor by the accumulation of small changes over generations. He believed that studying breeding by artificial selection of animals like pigeons would provide evidence.

Darwin spent 20 years gathering evidence and writing about his theory before he published it. He anguished over the controversy it would create in Victorian England. And, if the naturalist Alfred Wallace hadn't come to similar conclusions and written to Darwin for help in presenting them, it might have been even longer before the world read a word of The Origin of Species.