In the days of high child mortality, it was thought women should spend all of their child bearing years in marriage to maximize the most amount of viable children possible.That's true. In the Bible and in other primitive, ancient cultures girls were considered ready for marriage and child-bearing as soon as menses began.
Sometimes our American puritanical point of view on such things isn't a bad thing.
Child mortality isn't really an issue anymore, and women are no longer thought of as simply breeders.
