Well, look again. Humans are quite the only species capable of understanding at a higher level the reproduction and controlling it. So, yes, this plays a bigger

Well, look again. Humans are quite the only species capable of understanding at a higher level the reproduction and controlling it. So, yes, this plays a bigger role than environment, where humans can thrive in almost any conditions, if the technology is allowing it. No intrisic force makes a woman to have children and how many, just cultural and basic economy.