The 'why' is just what I find most lacking in this theory of memes. For me, memes beggar the question entirely. If an idea spreads, it must be because it is 'memetically' powerful, it is said. But why people have ended up expressing such ideas in the first place is the interesting and important part, and to explain this by simple 'spread' as with a virus is to me totally inadequate.
By the way, I don't know what to make of Dawkins example of 'Auld Lang Syne'. It must be a British phenomenon to add the words 'for the sake of' to the Robt. Burns song. I don't do this, and the two people I've asked don't either. So the practice spread in Britain but not, I'm guessing, in America. What is the reason? I have no idea, really, but why do regional and national differences of any kind exist? To say that it's because of memes does not, again, seem offer much real information.
Well, thanks for putting in a good word (sort of) for my gender!