because it does suggest some analogy with Natural Selection which is much more difficult to demonstrate.

Does it have to be any more than that songs that people like most get sung more and spread and less popular ones don't and tend to fall by the wayside? That small changes that make the song work better for listeners tend to be kept? That verses that don't make sense because they have been mis-heard or include words that have fallen out of use are dropped or changed?

I know more about paleontology than folk songs so maybe there is something I don't 'get'.