The Chicago text must have a literary origin.

We know that Stevenson created the song (though only four lines of it) to make Treasure Island just that much more entertaining. As Michael actutely observes,"Yo ho ho!" just doesn't appear in genuine shanties and traditional songs. Therefore any version of the song, with or without yo-ho-ho, must be derived, ultimately, from Stevenson.

Also, if less conclusively, the whole cannibalism-Davy Jones thing smacks of stage melodrama or an attempt to imitate it. Real shanty lyrics are less self-consciously creative. (I don't think there's a cannibalism-Davy Jones "motif" recorded by folklore scholars.) Furthermore, halliard shanties that tell a coherent story like this, with a beginning, middle, and end, are very rare: "Boney," "Lowlands," what else? And they give few details.

So the song is an imitation of an imitation. The evidence is inconclusive, but Starrett was probably right (for the wrong reasons) in thinking the whole story a good-natured hoax. When something sounds too good to be true....