It amazes me how little is said about posture these days. Without the correct posture dancing with a partner becomes difficult, man or lady. On a turn if the shoulders don't turn an equall amount on 123 Natural Turn Waltz for instance. The dance then becomes difficult and loses its beauty. A very simple test is to hold a piece of broomstick at about waist level and keep it there. Try a Natural Turn. Both sides come around an equall amount don't they. So is the turn instigated by the foot positions or by the body.. Remembering that in Modern the spine does remain straight and if we had three blocks of wood, under the ribs down to the bottom of the pelvis they will remain one on top of each other perfectly aligned.

"Remembering that in Modern the spine does remain straight and if we had three blocks of wood, under the ribs down to the bottom of the pelvis they will remain one on top of each other perfectly aligned. "

Aligned in position, but not in rotation.

And not even symmetrical aligned in position, because of the leftware stretch.

In reply to quickstep, i'm doing a lot of work to STOP my spine from being straight all the time. Like correct sway.
The '3 blocks of wood' argument is OK for the set-up but can't possibly be retained all the time while dancing.
They'll be changing orientation on several axes because of CBM and sway

Phil. Just to be argumentative I think that you will find that even in sway if your blocks of wood have gaps you are well on the way to having what is called a Latin Hip. The part above the pelvis stretch both side equally. Something to watch for is if practicing the sway to the left on its own just make sure that you are high on your left toe and not starting from a flat foot, which will give the wrong effect.

To add more about the alignament of the spine. It should be possible to do a Feather Step with CBM and CBMP and keep the spine aligned. Kick the hip even slightly leftwards and the line is broken. It should be possible to simulate the correct action by supporting ones self by using a table or chair just to see what it takes to keep the spine straight. Hopefully none of us try to step around the lady. We all know that the person going forward has the right of way, and the person going backwards is the one that clears a path. If this is not known we are in big trouble and would be better off with a spine made of rubber.

"We all know that the person going forward has the right of way, and the person going backwards is the one that clears a path. If this is not known we are in big trouble and would be better off with a spine made of rubber."

In reality, both partners need complementary CBMP shapes to make space for the outside partner step. If you literally get out of the way, you'll waste all your energly slingshotting around each other.

Most dancers except for at a high level end up reversing their hips almost to the opposite of CBMP during the course of placing the outside partner step, so someone is going to be off balance, distroted in shape, or simply going to have to get out of the way.