Remember that it's technically a valid evolutionary strategy to live to, say, 25, have a few kids, then off yourself. Suicide before reproduction is all that would be selected against.
Depends on how much your children need you actually. I've read somewhere that part of the reason women lose ability to bear children past around 40 is so they can take care of their grand children because that is usually more important at that point from an evolutionary point of view. It might have been a mere speculation but it kind of makes sense. Rather than take the time to bare and raise one child, that time is…
* Women stop having children after 40 because it's more important to raise the children you already have. * Women don't stop having children after 40 because bearing more offspring increases your chances of survival.
Your explanation barely makes sense even on its own merits. Surely, if nature wanted us to have N children and then take care of them, it would have set a cutoff on N, rather than on the time. What if someone has no children before 40? Is it to their evolutionary advantage to care for the children they didn't have?
Or, if your explanation were true, why would women not spend ten years gestating and given birth to a healthy 10-year old? It's illogical to design a system that can pop out one baby every nine months and then say "okay now that you've had anywhere from zero to thirty children, it would be best if you stopped and took care of them.