I don't think 'Darwin explains Einstein'. I don't believe that the biological theory of evolution explains why human beings ought to be able to devise such ideas as the Theory of Relativity. In fact, neither did Alfred Russell Wallace, who is often said to be a co-discoverer of the principle of natural selection, and whose own work on the idea was what finally impelled Darwin to publish his thesis, for fear that he might have his theory stolen out from under him. (Wallace's doubts about the Darwinian account of the descent of man was published in an essay by him called Darwinism as Applied to Man
. His ideas are mostly discounted because of his interest in 'spiritualism'.)
But the same general objection can be made with regards to genius. Why should a Mozart or a Bach be born? I hope you don't want to argue that it is because 'their genomes are more likely to proliferate'. I find the argument unbearably vulgar. I don't think genius is explicable, full stop. Furthermore, from the viewpoint of strictly Darwinian theory, there is no reason why many human attributes should exist. To say that they only exist so that we can continue to proliferate barely amounts to philosophy in my opinion.
He that knows it, knows it not.