The whole idea of hair is to protect the head (from the Sun & to act as a sort of dry lubricant to divert and cushion blows.) As one becomes more civilized as they get older, wiser, and much smarter than they were at 20, perhaps losing that essentially useless stuff- that just grows and must be continuously maintained, is a sign of sophistication? I think that the more evolved a person’s genes are the less hair they will actually have (or need!) Culture and customs say the other, that hair makes a person attractive, but these are voices that shout from the distant past.