A young 12 year old girl would have witnessed births by many women by the time she reached 12 and would be fully aware of periods, child bearing and birth long before these things happened to her. She would already have been learning about child care well before she reached puberty. Her whole life would have been leading up to the time when she could finally marry and have children of her own.

So in many ways, a 12 year old girl in pre modern times would have had the maturity level of what many 18 or even 20 year old girls have today.

Also we must keep in mind that before the modern era, families took care of other and were much closer. So when a 13 or 14 year woman had her first baby, her female relatives, whether they were cousins, or aunts, or even her mother were all there to help her learn the ropes of motherhood. Today the tribal family structure has all but been eliminated.

Men can father children at any age beyond puberty

Unlike women who ovulate once a month, and are only fertile for about 5 days, the typical man (unless he has a medical condition) is in essence “fertile” every day. A man completely replenishes his sperm every 24 hours. Before recent research, doctors used to tell men to wait every other day to have sex with their wives during her fertile period. Then they discovered that is was in fact better for them to have sex every day, as all the sperm is at its best every 24 hours or so.

A man since he was not responsible for caring for the child, but for the teaching and disciplining of the child, did not need to have the physical strength and endurance that a woman needed in her duties of child rearing, and this is why a man has no expiration date on his ability to produce children.

The fact of God’s creation in human biology is, men are built for fathering multiple children with multiple women at the same time. They are also built for fathering children with multiple generations of women, as their first wives age and cannot have children, they can continue fathering children with younger women.

This is why men have such a stronger sex drive and can compartmentalize relationships with multiple women, much better than the average woman could with multiple men. Not to mention that a man has a never ending supply of child producing sperm. On the other hand, women are designed with a shelf life when it comes to having children. How else do you explain the extreme disparity between the male and female reproductive systems?