I'm currently reading Stephen Jay Gould's Ever Since Darwin, where he recounts some of Darwin and Marx's interaction:
The most ardent materialists of the nineteenth century, Marx and Engels, were quick to recognize what Darwin had accomplished and to exploit it's radical content. In 1869, Marx wrote to Engels about Darwin's Origin:"Although it is developed in the crude English style, this is the book which contains the basis in natural history for our view."
Marx later offered to dedicate volume 2 of Das Kapital to Darwin, but Darwin gently declined, stating that he did not want to imply approval of a work he had not read. (I have seen Darwin's copy of volume 1 in his library at Down House. It is inscribed by Marx who calls himself a "sincere admirer" of Darwin. Its pages are uncut. Darwin was no devotee of the German language.)
Darwin was, indeed, a gentle revolutionary. Not only did he delay his work for so long, but he also assiduously avoided any public statement about the philosophical implications of his theory. In 1880, he wrote to Karl Marx:"It seems to me (rightly or wrongly) that direct arguments against Christianity and Theism hardly have any effect on the public; and that freedom of thought will best be promoted by that gradual enlightening of human understanding which follows the progress of science. I have therefore always avoided writing about religion and have confined myself to science."
Reading more about Gould (whose contributions to evolutionary theory include punctuated equilibrium), it appears that he had some fondness for Marxism as well. From Stephen Jay Gould, a Man for All Seasons:
He was an ardent opponent of the evils created by capitalism and employed his pen and wit to ridicule social injustice wherever he saw it.
Interesting stuff. This may be worth an afternoon WILFing on Wikipedia.
