Darwin (my hero) suggested that language evolved from "rhythmic chants." I'm not too sure that I agree with him on this, but recent developments lend this idea some credibility. For instance, one might ask what the absolute essential ingredient to music is. Well, rap music (for purposes of this discussion, I will consider it music) has pared music down to two ingredients: rhythm and lyrics, and since I can't understand the lyrics (nor have any wish to), that leaves rhythm, which my musician son tells me can actually be quite sophisticated.
So, one could make a case that the one thing music has to have is rhythm. What next, then? I'm thinking melody. Then harmony? Then lyrics?
There are of course counterexamples to much of this. Gregorian chants, for instance, have lyrics but only the most basic melody and rhythms, and no harmony at all.
Which leads me to nonsense songs: those popular songs in which the lyrics are either silly ("Yummy, yummy, yummy; I've got love in my tummy"), or literally without sense (Does anybody remember the song -- spelling approximate -- "Hut sut rawl sittin' on a rilliraw"?). In these songs, what ever pleasure we get from them comes largely from the melody and rhythm.
Other songs might include "Purple People Eater," "Yellow Polka Dot Bikini," "Mairzy Doats," and almost any camp song you can think of.
Certainly we get pleasure from the combination of rhythm and melody. If, though, we consider such things as sporting event cheers (rhythm and lyrics but no melody), and much of poetry (ditto rhythm, lyrics, no melody), we see that the one constant thread is rhythm.
Son of a gun. Maybe Darwin had it right all along.