|Charles Darwin, c 1878. [image in the public domain]|
Charles Darwin, in his 1859 book On the Origin of Species By Means of Natural Selection, or the Preservation of Favoured Races In the Struggle For Existence, promoted a view of the natural world that involved all life sharing a common origin, and all organisms changing over time through a process of 'descent with modification,' whereby traits that give organisms an edge in survival get passed on to successive generations because those organisms that possess such traits generally have an easier time surviving to breed successfully. Darwin's work is essential to our modern understanding of evolution, and thus to much of biology in general.
In addition to just being the father of evolutionary science (no big deal, right?), Darwin was an avid collector of beetles, an ardent pigeon-fancier, a dedicated studier of barnacles, a world traveller, a well-respected figure in his community, and a loving husband and father — the last is especially notable in a time when familial relationships were often rather detached. Darwin was made a Fellow of the Royal Society in 1839; awarded the Royal Medal in 1853 for his works on barnacles and the geology of coral reefs, volcanic islands, and South America; awarded the Wollaston Medal in 1859, the highest honour of the Geological Society of London; and awarded the Copley Medal in 1864 for 'outstanding achievements in research.'
Down House, the home and gardens of Darwin and his family, is located in Downe, in the London Borough of Bromley, and is open to the public. Darwin is interred at Westminster Abbey. For more about Darwin Day, click over to darwinday.org.