It's interesting that the sexes tend to exaggerate differences that are already there. So, women are less hirsute than men, and therefore they shave themselves completely to exaggerate their lack of hair, while men tend to exaggerate their beards. In places where women tend to have more hair or for longer, like the scalp (many men go bald with age), in that case, again, women tend to sport long hair, and men tend to shave their heads even when they have plenty of hair. So we exaggerate our differences to emphasize our femininity or masculinity, same as some birds put extra feathers on their tails.