I've had some discussions recently about evolution, and more specifically about how Darwinian thought really has little to do with modern evolutionary theory. This led me to wonder what exactly, if anything has been proven wrong about Darwin's take on evolution? Was he wrong about aspects of natural selection? I know he later adopted Herbert Spencer's phrase "survival of the fittest," which is decidedly ill fitting in explaining how natural selection really works. Obviously though, the phrase must have been fairly consistent with how he interpreted natural selection, or he wouldn't have used it. So, have any aspects of Darwin's theory of evolution been proven wrong in the name of better representing how evolution works? Or have modern evolutionary theories just continued to build on it? I've tried googling this for an answer, but nearly all of the search results are in the form of religious groups trying to discredit evolution...and this is definitely not what I'm looking for.