February 13, 2009 - This year marks the 200th anniversary of Charles Darwin’s birth and the 150th anniversary of his most influential publication, On the Origin of Species, in which he introduced evolution by natural selection. Darwin's ideas had a profound influence on 19th-century thought, and today evolution is a cornerstone of modern biology.

Darwin's life represented the essence of science. He was naturally curious and reflective, always gathering evidence to explain the world around him. The five-year journey on the ship HMS Beagle was a turning point in his life. His observations about the diversity and distribution of species spurred his thinking for The Origin of Species, and Darwin spent 20 years examining evidence and writing about his theory before publishing his well-known book. He anguished over the controversy it would create in Victorian England, and if 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 On the Origin of Species was published.

Natural selection remains the primary explanation for adaptive evolution. It is the process by which organisms with favorable traits survive and reproduce more successfully than other members of their species that do not possess such traits. Over time, this shift in the frequency of specific traits in a population can lead to small and large changes within that population, and sometimes to the emergence of a distinct species.

In celebration of Darwin's achievements, the National Academies have redesigned their evolution resources Web site, a collection of books, reports, statements, papers, and articles about evolution. This new site organizes information and materials for groups such as educators, business leaders, and legal experts, but anyone with an interest in the topic and issues related to evolution should find this site useful and accessible. It also provides a list of scientific definitions, one of the most requested items by visitors to the Academies' original evolution resources site.