Earlier quoted context omitted.
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…
I dislike these kinds of explanations because they seem like ex post facto rationalizations. An explanation that could have gone both ways explains nothing: * 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 it…
To design? Are you a creationist?
Assuming you're just confused, evolution doesn't "design" life. It's just a "whatever works" process.
For example, angler fish have a lure that resembles prey for their prey. This has been selected by the eyes of their prey. It's not that the prey wanted their predator to fool them, it's just that angler fish with bad lures starved and died off.
In the case of humans, if what your parent comment suggests is true, then it would just be that some women had some sort of defect where they couldn't give birth after some point and that turned out to give their grandchildren an advantage over the grandchildren of women without the defect. Over a long period of time, more and more descendants with defective reproduction genetics would survive compared to those without and so it becomes prevalent.
That's how evolution works.