I recently read Stephen Jay Gould's essay on "Natural Selection and the Human Brain", from his collection, The Panda's Thumb.
It outlines the rift between Charles Darwin and Alfred Wallace on this question, one which persists as the key ideological battleground between science and religion today, and accounts for recent polls suggesting that no more than a quarter of Britain's population "believe" in Darwinism.
In Gould's explanation Wallace was an arch-proponent of what we now call "intelligent design" the notion that Darwin did god a massive favour by demonstrating the coherence of his grand and beautiful works.
I was somewhat surprised therefore to read John Parrington's benign treatment of Wallace (Socialist Review, February 2009). I think Parrington overplays both Wallace's claims as a socialist and Darwin's undeniably bourgeois status. Both are secondary to the truth of their work.
Besides, I believe from Adrian Desmond and James Moore's masterly biography that the question of class is far more dialectical with Darwin. The inexorable conclusions of his own scientific imaginings scandalously contradicted his social standing.
But it wasn't just the worry of being deemed a traitor to his class that delayed his "coming out" with his revolutionary theory. Darwin was painstakingly amassing as much convincing scientific evidence as possible to make it logically unassailable. Almost in spite of his class, because he was conscious of the enormity of his proposals, he made sure his work was as unimpeachable as then possible. Good as he was we've had to wait a while for DNA and the Human Genome Project to confirm the value of his labours.
Darwin tactically avoided the specific question of human origins in The Origin of Species lest it might detract from the impact of his theory regarding the rest of the biological and geomorphological world. But he spoke and corresponded about it a lot before publishing works on it in later years. Darwin remained to his death an opponent of any version of creationism, even though the state, meekly assisted by his god-fearing widow, tried to reclaim him by interring him in Westminster Abbey.