In his 1850 work The Origin of the Species, Charles Darwin presented the notion that all species evolved from earlier forms of life and that they change and adapt to their environment as a result of what Darwin called natural selection. Investigate Darwin's theory of evolution, which has become the organizational principle biologists use to explain the life sciences. Includes five segments: • A New Look at An Old World • From a Single Cell • Evidence for Evolution • Evolution in Action • The Origin of Species