What they found is that education and equality are the fastest way to population stability.
Particularly making females equals to males and educating females is a sure path toward fewer babies.
Oppression and poverty are the enemies of this planet.
That means we have to look at our voting systems, too, because there are some rats inside the Democratic Theater right now.
Like it or not, but the USA, UK, Canada, France and India do not have the best democracies in the world. You may say that many do well in the baby-limiting business, but bad democracies can actually put extreme pressures on other nations (including non-democracies).
Take the USA. Voters are competing with the voters for the win.
That alone is divide-and-conquer.
Voters step into the voting booth, and some 40% to 49% of the voters are eliminated right away because they voted for the losers.
It means that the winners do not need to listen to them, and that is where the elite gets its power, suppressing the population at large. And it doesn't stop there. They need not pamper to all voters that got the one they wanted because the winners fight with the winners, too.
That means that when 60% of the voters get the one they wanted, then 30% of all voters equal the 'majority' decision. And that is how the elite suppresses society, with the divide-and-conquer game. In two rounds, all voters are diminished to 30% and these voters can be ignored at times as well through sitting on one's hands and fighting over non-issues.
By not empowering all voters, these false democracies put unnatural pressures in the social-economic reality of the planet. Folks at the bottom can't get their fair share of the cake, and that means foreign investors love to flock to these nations where they get more for their invested money than in nations where the entire population benefits from growth.
So, nations that want to do things right for all end up competing with nations where money does not flow to the bottom of those societies. And that is where the baby production of the world can be improved the most. If we take the poverty-inducing voting system out of the picture, we make this a better world for all (with fewer babies).
Yes, equality is really that powerful. If women are made equals in society, and if the bottom of society is lifted up through fair elections, then the world can lower its baby output.