Over the years, physicians, artists, and scholars have spent much time determining the ideal facial shape and proportions of beauty. Knowing what is ideal, is important to understanding how the face changes with age. There is an exhaustive body of literature on this subject that has found that certain proportions are considered beautiful by many different people from diverse cultures, backgrounds, and societies. Rather than summarizing everything, I will highlight two concepts here.
The first is the triangle of youth. The triangle of youth refers to the overall shape of the young face especially in women. The triangle of youth is actually an upside down triangle formed by three points: the apex of each cheek, and the chin. This triangle highlights the importance of prominent cheekbones in the youthful face.
As we age, our cheeks hollow and flatten and jowls develop. This causes the triangle to turn right side up.
The other concept of proportion that I will highlight is that of the golden ratio. The golden ratio is literally 1 to 1.618. There have been artists, architects, and mathematicians, over the centuries who have concluded that everything that is aesthetically pleasing, whether it be man-made or natural, is in this proportion. One retired physician in California has explored how the golden ratio applies to ideal facial proportion extensively.