When the eminent naturalist Charles Darwin returned from South America on board the H.M.S Beagle in 1836, he brought with him the notes and evidence which would form the basis of his landmark theory of evolution of species by a process of natural selection.This theory, published as The Origin of Species in 1859, is the basis of modern biology and the concept of biodiversity.It also sparked a fierce scientific, religious and philosophical debate which still continues today.