February 12 is the two hundredth anniversary of the birth of a man who changed our understanding of the world and our place within it. A sculpture of Charles Darwin as an old man looks benignly down at visitors and the skeleton of the diplodocus in the Central Hall of The Natural History Museum in South Kensington. Until April 19, you can learn more about him as an energetic young man and the 20-year birth pangs of his On the Origin of Species by visiting their Darwin exhibition.

Of his time on HMS Beagle, which is the subject of the first gallery, the naturalist wrote: “The voyage of the Beagle has been by far the most important event in my life, and has determined my whole career. “ But it nearly didn’t happen because Charles was destined for a career as a clergyman and his father, Robert, was against the expensive trip, which he needed to finance. Fortunately, the opinion of his respected Uncle Jo, the industrialist and visionary Josiah Wedgwood II, won the day.

Darwin features some of the creatures he would have seen for the first time on that epic journey including live green iguanas and horned frogs from South America, along with fossil specimens he collected. During the five-year Beagle expedition, Charles shipped home 1,529 species preserved in spirit and 3,907 labelled skins, bones and other dried specimens, so exhibition designer, Alex Gaffikin had plenty to choose from.

Darwin set off with enthusiasm, in December 1831, and despite his miserable sea sickness was initially enamoured by the sea. When two years turned into five, his opinion had changed and he wrote home: “We are utterly homesick.”

Robert Fitzroy, the captain of the Beagle, was a wealthy nobleman who spoke warmly of the young naturalist at the start of the voyage. Their first dispute occurred during a trip into the interior of Brazil. Darwin was horrified by the cruelty meted out to the slaves whereas Fitzroy’s opinion was that they were ‘happy’. The disagreement was so fierce that Darwin nearly left the ship. How much chance affects even the greatest lives!

Their relationship seems the stuff of Greek tragedy for Fitzroy was in Oxford in June 1860 on the day of the great debate on Darwin’s theory of evolution, based on the observations he made on that epic journey. Waving his Bible and shouting “Blasphemy”, Fitzroy was racked with feelings of guilt when he realised that he was indirectly responsible for this theory that rocked his vision of the world. On February 12, to mark Darwin’s birthday, in the location of the June 1860 Great Debate, Oxford’s (then new) Natural History Museum in South Parks Road will stage a ‘conversation’ between Richard Dawkins and (Lord) Richard Harries (recently Bishop of Oxford) on Darwin’s contribution to modern biology. Haydn’s Creation, performed by the Oxford Philomusica, at the Sheldonian Theatre, is an apt choice for the concert preceding this ‘debate’. I expect it will be rather less controversial than the one between Bishop Samuel Wilberforce and Thomas Huxley.

The London exhibition has a reconstruction of Darwin’s study at Down House, his country home in Kent, where he advanced his theory that all life evolves by natural selection. In a note to his wife and cousin Emma (Wedgwood) in 1844 he wrote: “I have just finished my sketch of my species theory. If, as I believe . . . my theory is true, and if it be accepted even by one competent judge, it will be a considerable step in science.” So why did it take him until November 1859 to publish On the Origin of the Species? When Darwin began his studies, the general belief was that organisms were unchanged since their divine creation just a few thousand years before. Visitors can see how Darwin’s contemporaries arranged specimens via an antique display case filled with exceptional mammal, reptile and bird skeletons. Darwin expected a vitriolic reception to his ideas for he was sensitive in the knowledge that many would feel their belief system threatened by the notion that species evolve and were not created on a single day. The spur to publish was a letter from the British naturalist, Alfred Russel Wallace, who independently conceived a theory of natural selection identical to Darwin’s, but based on completely different observations, on the other side of the world. Wallace acknowledged Darwin was first and there was no jealously between the two men, both presenting them on the same day in 1858 to the Linnaean Society of London. “Survival of the fittest” was not a phrase coined by Darwin. He borrowed it from the economist Herbert Spencer, on Wallace’s advice. It does not appear in On the Origin of Species until the fifth edition.

The show includes a video biography of Darwin, narrated by his great-great-grandson, Randal Keynes, author of Darwin, His Daughter, and Human Evolution. The exhibition ends with ‘Evolution Today’ giving examples of modern evolutionary research and showing how Darwin’s theory has been enhanced and enriched by subsequent discoveries in palaeontology, genetics and molecular biology.

Videos and interactive exhibits help visitors understand concepts such as adaptation to environment and natural selection. Screens show some of today’s leading scientists explaining Darwin’s continuing impact on modern society and science and how his theory is the foundation of all modern biology.

The Oxford University Museum of Natural History will have its own exhibition in the Upper Gallery for much of 2009 and half-term family activities are on the theme of evolution.

For more information go to www.darwin200.org