In 1859, an amateur British naturalist published a book of findings that shook the scientific community to its core and changed the structure of religion and science as we know them. The product of over 20 years of research, The Origin of Species challenged the popular belief that species could not evolve and argued that species can adapt to their environment and develop accordingly. Although other scientists had observed some of the phenomena that Charles Darwin addressed, he was the first to theorize that natural selection, and later, evolution, were viable explanations for the origins of life. The implications of Darwin's findings still reverberate today, in the classroom, in the courtroom, and at the highest legislative levels. Lively thematic chapters explore how Darwin came to the conclusions published in The Origin of Species—and in later works such as The Descent of Man—from his early years at Cambridge, to his observations of species on the HMS Beagle voyages, through the 20 years of research that culminated in Origin. Also included is an insightful discussion of Darwin's impact as it is felt today, from movies and popular culture to the current Intelligent Design controversy. Biographies of influential figures, primary source letters and selections from Origin, a glossary of terms, and an extensive annotated bibliography round out this accessible work.