Long ago a friend told me that all of Reggae music was copped from old R & B records from the Memphis/New Orleans axis. His attitude was that it was just stripped down, "dumbified" R & B. I thought he was being harsh.
There's a great article at the Oxford American site this month called "That Chop on the Upbeat," by John Jeremiah Sullivan, where he makes the same point about the R & B thing, but with academic precision rather than glib bitchyness. (He tolerates Ska and Reggae very well too, not like my friend.)
Evidently Jamaica had no domestic record business until around the time Ska came along, 1960 or '61. Before that the DJ's made trips to America to scout around for records that Jamaicans would like. They had great taste too, they found and popularized a lot of great records (like this one).
Maybe I'll listen to the rest of the stuff mentioned in the article and have more to say on the subject.
(Disclaimer: I love Reggae, O.G. Ska and Two-Tone Ska, and I love the Classic R & B too.)