Title page from Darwin�s �The Origin of Species�, 1859.

UNITED KINGDOM - APRIL 08: Charles Darwin (1809-1882), British originator of evolutionary theory, was employed as a naturalist on HMS Beagle from 1831 to 1836. He first made his name as a geologist, but is remembered for his momentous contributions to biology, primarily his demonstration that evolution has occurred and his discovery of the principle of natural selection of heritable variation as the cause of evolution. His most famous work, 'On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life', was published in 1859. The book was both violently attacked and energetically defended throughout Europe, but succeeded in obtaining recognition from almost all biologists. (Photo by SSPL/Getty Images)