yeah, I never understood this

There are over twenty bones in the skull, and they all are part of the same dynamic tension-structure. Each bone in the skull contributes in its own way to the maintenance of balanced tension throughout the skull. When 22 bones interact with each other, it's not just 22 ways things can go wrong, but 22^22 ways. Or something impractical like that.

So the details are complex and probably vary from face to face. Then there is the problem where all movement is inherently relative to something else. What is a good anchor point for tracking a changing facial characteristic when everything about the face is changing simultaneously? And not just that, a head with changing proportions has a changing center of gravity, and therefore changing default patterns of movement.

It's only the combined effects of all change that is taking place that can be conveniently described as "a general upswing of the face". I tried to demonstrate some general changes that the skull can go through according to my current understanding:

From strictly functional perspective, what you are doing is balancing the center of tension in the skull between your eyes and over time the skull will "collapse" around concave this tension point by making both the forehead and the jaws curve towards it. Recessed face is the result of a tension point that has been allowed to creep  too deep into the skull, dragging the center of gravity behind with it.

Fascinating and insightful. This has given me a new sense of clarity when it comes to optimizing my oral posture. Thanks a lot 🤔