So you're saying that the median marriage was forced back then? I don't see why the same reasoning wouldn't apply to men as well or who was forcing people into marriages besides some vague idea about "the patriarchy or something".

I was responding to OP's point about how our bodies are better suited to have children when we're younger. I think that's scientifically supported. My main belief would be that having children when you have peak fertility probably goes hand in hand. Birth control is a good hypothesis, you could say it broke this link.