Geriatry... As in, becoming geriatric.
Oldentry might also be an option.
...or paleoteny, its opposite being neoteny.
Mid 20s for me. Not from the ear canal, but I have hairs growing along the helix on both of my ears. On the plus side, I now know what that part of the ear is called.
Drew Carey had some material about this. I don't remember the whole bit, but part of it was about how after puberty, all your zits migrate down your back to your ass. 😆