Congratulations on a great book, not only helpful but very interesting intellectually. One interesting question you do not address (wisely I think) is whether the superior posture seen in developing countries come solely from cultural influences (perhaps implied in the book). My n=1 experience suggests there may be other causes.
My question is whether it is possible to substantially improve posture of the upper back and neck with the practices and exercises in the book, given your clinical experience. For a long time I have had an occasional , manageable "sore back" ie muscle spasm which I controlled by exercise and stretcing. At present there has been no back pain for about a year, which is coincident with a diet change (quite surprising) and noticeable changes eg I can comfortably sleep on my back. That improvement motivated me to try the 8 steps and so far there have been small but noticeable changes. A related questiion is re rounded shoulders, my condition. Can this be caused/aggravated by constant sleeping on one's side? I hope you can find time to answer.