Doc,
Very interesting. I wonder what the worldwide average is. If you think about it, the lifespan of women of childbearing age in developing countries is probably a lot less than here, and subsequently (you would think) that they'd need to be able to procreate at an earlier age (I think a lot of cultures marry by the age of 13-14 or so). So if this is true, since the women here live longer, and would be of childbearing age longer, (a woman of 57 gave birth to twins this week) then there should be no change or even a lengthening of prepubescence.