If I (and I expect most men) figured out women by 8th grade, the world population would double in a year.
Sure, girls will tell you that they wanted sex back then, but I don't think they understand that I had a boner about 18 hours a day. Now its down to about 12 hours
.
So god (or evolution) decided to make girls like a 20 sided rubix cube. By the time that you figure it out, you are really tired and old.