Hermione's Hair.

It is a mildly interesting fact that Hermione Granger only wears a fringe in the first two Harry Potter movies. Once she starts growing up it disappears.

This indicates to me that the showing of the forehead is something of a rites of passage experience in the world of women. I wonder whether it has anything to do with ancient mating rituals. And should I assume that the move from centre parting to side parting indicates something even deeper?