July 1, 1858

Although the bicentennial of Charles Darwin's birth and the sesquicentennial of the publication of On the Origin of Species take place in 2009, the celebration of Darwin's year begins July 1, 2008.

On that date, On the Tendency of Species to form Varieties; and on the Perpetuation of Varieties and Species by Natural Means of Selection, two papers by Charles Darwin and Alfred Wallace respectively were read at the Linnean Society. The papers were subsequently published in Journal of the Proceedings of the Linnean Society of London. Zoology 3: 46-50

See Darwinmania! in The Wild Side column of Olivia Judson Wednesday, June 18, 2008 edition of the NY Times and the article, On the Origin of a Theory by Richard Conniff, Smithsonian, June 2008 issue for brief overviews of the development of the theory and why Darwin deserves the credit.