The history of science helps explain why the common sense and experiences of our daily lives seem increasingly remote from what contemporary science suggests is actually going on. The more we know, the more mysterious the universe actually seems.
How could natural selection operate so that "the good ones spread in the population" if there were no positive variants in the first place? That is why I am confounded by Jerry Coyne's comment that he can explain natural genetic engineering by "garden variety natural selection."
Was Darwin simply mistaken about the gradual nature of hereditary variation? Such ignorance would be unavoidable before we knew about Mendelian genetics and DNA. Or was there a deeper flaw in the theory that he (and Alfred Russell Wallace) propounded?