Correct me if I'm wrong, but, didn't ska and rock emerge at about the same time, around the early 50's late 40's? it changed as the world conditions changed, a lot like rock. I think reggae popped up around the late 50's. Reggae reminds me more of the blues and ska, I think, has the same attitude as rock, ever-changing along with the attitudes of culture and adapting to situations around the individual artists. Reggae, concerning the blues, stemming from african origins and usually themed with ideals about coping with bad situations and about close knit community activity, modeled after african tribes, which in my opinion have to do a lot with the Rastafarian beliefs about being stolen and returning to the promised land (Africa) If that makes any sense at all (I'm out of long-winded breath!)