Odd metered tunes are quite common in Balkan folkmusic--including many in 5--in addition, there are a lot of German folkdances in odd meters, including five. The odd meters seem to be a holdover from pre-classical music, In the era of Classical music they smoothed out the rhythms in much the same way that it cleaned up the modal scales, so I kind of always have assumed that a lot of traditional melodies that we think of as being 4 actually had been smoothed over from 5 when they were assimilated into the musical mainstream--

In balkan music, the pulse of a 5 rhythm has the same feel as a heart beat, which is also the iambic foot in poetry--In odd moments, it strikes me that, given that the iamb is about the most common poetic foot, even in English verse, that that wobbly five pulse was once the most common one in music, as well, given that in ages past, verse tended to be sung--

I admit that this thinking is strictly supposition--However, back in my Balkan dance band days, we regularly stretched our Bulgarian sets by taking traditional "Western" melodies and reframing them in odd meters--Not only was"God Rest Ye Merry Gentlemen" was perfect for playing as a Pajdusko(the Bulgarian 5/8 dance) it made the transition so smoothly that it was generally not recognized as a non-Bulgarian tune, even by serious Balkanophies--