Ooh, now we're cookin'!

Steve--
I think your and Dave's call for lateral thinking is very wise. To elaborate my thought (*so far*): I think the physicality of pronouncing "hi-lo" may have indeed been a/the essential determining factor of its origin. Once it was created, it then would have become something culturally specific.

We do know that at some point it was rationalized (in more than one way) as a meaningful word -- even if that was "a word whose meaning is unknown." But at what stage and by whom?

There are no examples attested before the 1840s. There are a lot of reasons why it may have been around a long time before that and yet was not documented. But I tend to feel that this is a distinct enough phenomenon (the "h" pointed out by Steve, along with the "l") and that such phenomena have times when they started. I think it's safe to imagine "hi-lo" as something that became popular around a certain time.

If it sprang from the physically-likely, meaningless vocables that worked well in song, then at this "certain time" it was starting to become conventional.

Let's assume it was meaningless vocables to begin with. The early reference to "Johnny come down de hollow," then, must be read as a rationalization. By whom? Did the listener rationalize it, or had the singers already done so? It *seems* like "hollow" really was intended -- it makes grammatical sense. This example makes it seem as if maybe "hi-lo" was *not* nonsense vocables, but rather a hearing or transformation of hollow/holler. Either that, or the vocables had already been rationalized by the (presumed) "cultural insiders". Another possibility is that there were hollow/holler songs and there was hilo and that sometimes they got crossed.

I really don't know how to explain it, but I am comfortable with a category of word that is both vocable and has a sort of connotative meaning at the same time. The way I am seeing "hi-lo" used, both as a shouted chorus and as part of otherwise meaningful phrases makes sense intuitively. Perhaps it does sort of occupy the same linguistic category as "hello"/"hallo". I supposed we'd call that a "vocative." Compare the ejaculation "Oh!" with the vocative "O"!! So despite trying to reason out some of this stuff, I feel it doesn't necessarily need any reasoning. Still, I am curious about it.

I like Jerry's example from the Caribbean singers, "Johnny come down with a hilo". And I agree on one level with Lighter's comment that it was "Presumably because "hilo" didn't make any sense to the singer to begin with." On another, probably subjective, level, I feel like the Caribbean rendering does truly make more sense. The Barrouallie (sp) Whalers sing it like that, and it's my pet preference to sing it like that, too, when I'm singing to myself (say, while shaving in the morning). I suppose I like it because it negates the popular "TO Hilo", which makes it sound like Hilo is a place (and which I think is the least likely scenario). The literary "down de hollow" is yet another variation that belies the notion of Hilo as a place-name, as does the early chanty reference "gone A [hilo]".

I am intrigued by Steve's question
Why is the aspirant always present? Presumably it is either very pronounced by the singers, or the collectors instinctly recognised it as a well-known word, otherwise wouldn't at least half of them have printed/noted down 'Ilo'?

I am unclear why you think at least half would write "Ilo." Is this because of the tendency of many UK English speaks to "drop" the "h"? Or does it relate to Spanish silent pronunciation of "h" (if we are dealing with the Peru idea), or...? In any case, I think once all the references are posted it will be more clear. It may be that not that many individuals, operating independently, documented the song. I am going to guess that most of them read earlier authors, and so the idea of "hilo" as an established form was there.

I am about to look at Davis and Tozer, who were first to offer an h-less form.