Charles Darwin is famous for saying, "[a] scientific man ought to have no wishes, no affections, - a mere heart of stone". However, whenever I learned about Darwin from secondary sources, there is always great mention of his passionate love for specific organisms like worms. He kept collections, he gardened, etc. That sounds like the behavior of someone who has tremendous affection for the natural world. So did Darwin change his mind? Was he being oblivious and hypocritical? Was he commenting on how scientists should be and not on what they often are (nerds)? Or something else entirely? I've never read this quote in it's original context and would love to hear from someone who has done primary research into Darwin's life.
Darwin's "heart of stone" comment refers to the idea that scientists should not develop an affection for a theory or law that goes beyond the evidence, and be ready to part with said theories or laws if it appears they are false. It is a statement about going into the world without emotional attachment to what you are going to find. It does not mean that scientists should not care generally, or care for their work, or revel in the glory of nature, or anything like that. It is not a contradiction in the slightest that Darwin could believe that scientists need to be hard-hearted when it comes to abandoning ill-formed theories (however dear to them), but that he enjoyed his work, his garden, his worms, what have you.
This is the original context and the footnotes embedded make it more clear what he is talking about with Huxley (a supposed law of Brullé's regarding vertebrae that Huxley said was wrong). It is of note this is a private correspondence and not some broader public statement by Darwin.
Darwin's entire approach to his work was anything but hard-hearted or hard-headed. He was, in the tradition of his hero, Alexander von Humboldt, a Romantic scientist, one who gloried in the sublime unity of nature and who felt that reductionism had its limits. See e.g. Robert J. Richards, The Romantic Conception of Life: Science and Philosophy in the Age of Goethe (University of Chicago Press, 2002), esp. chapter 14.