I've referred before to the command in Genesis to "fill the earth". Looking at a graph like this, it seems that this at least is one command that humanity has succeeded in carrying out.
So what next? Professor Cohen makes his case for studying demography as follows:
I’d encourage any freshman, sophomore, junior, senior, adult, high school student—I’m not age prejudiced—anybody who wants to do three things to consider demography. It’s not the only field that offers these attractions but it does offer them in spades. It’s really very attractive. First of all, demography gives you tools and analytical perspectives to understand better the world around you. That’s understanding.
Secondly, it gives you equipment to solve problems mentally. It’s mentally exciting; you really have to use your noggin, and if you’ve got one use it or lose it. So it’s use it. And third, it is the means to intervene more wisely and more effectively in the real world to improve the wellbeing, not only of yourself—important as that may be—but of people around you and of other species with whom we share the planet.
So it prepares you to go out and do something that’s worth doing for a larger good than only yourself. So there’s an old saying, “If I am not for myself who will be; but if I am only for myself what am I; and if not now, when”? So now is the time. Pull up your pants and get to work.