Would you, at six years of age, even recognize the person you are now? We all go through profound changes in a typical lifetime.
The normal processes of life--working, loving, eating, bearing children, sleeping--transform us over time. And that's in addition to things we do to ourselves, like weight-lifting and dieting and getting tattoos.
Gavin Francis, physician and author, considers the many things that happen to bodies in a book called Shape Shifters.