“WHEN on board H.M.S. 'Beagle,' as naturalist, I was much struck with certain facts in the distribution of the inhabitants of South America, and in the geological relations of the present to the past inhabitants of that continent. These facts seemed to me to throw some light on the origin of species—that mystery of mysteries, as it has been called by one of our greatest philosophers. On my return home, it occurred to me, in 1837, that something might perhaps be made out on this question by patiently accumulating and reflecting on all sorts of facts which could possibly have any bearing on it.” 

Charles Darwin, On the Origin of Species 

Darwin200 is an international programme of events celebrating Charles Darwin's scientific ideas and their impact around his bicentenary on 12 February 2009.

First published 150 years ago in the book On the Origin of Species, Darwin’s ideas live on as the central organising concept of modern biology. The geneticist Theodosius Dobzhansky said “Nothing in biology makes sense except in the light of evolution."

Yet when it was first published Darwin’s book provoked a storm of controversy, some of which continues today. What turned a fairly ordinary young man into the great thinker who wrote the Origin of Species?