I still like the "evolution" theory . . . I remember doing the Jitterbug with my Mom back when I was 10 years old through about age 19. I certainly am a better dancer now, than I was back then. Is that not an improvement? Yes, I know, I'm comparing WCS and ECS to Jitterbug, and dancing with my Mom versus a partner, and inexperience versus experienced. But she was the NY State champion, so she says, and I really enjoyed dancing back then . . . she was good. I turned out to be better . . . so I say!