It's important to balance this analysis with the fact that the human population of the Earth, in absolute terms, grew more during the last 60 years than at any

It's important to balance this analysis with the fact that the human population of the Earth, in absolute terms, grew more during the last 60 years than at any other time in history. Or consider, there were about 4 billion humans on the planet when I was born, there is almost 8 billion now. There are situations where it is good to talk in percentages. There are other situations when it is good to talk about absolute numbers. Assuming the planet has some absolute environmental limits, then it is the absolute number of humans, rather than some percentage growth rate, that matters. Why are people having less children? Surely part of it is because of the strain of having to absorb the historic population surge that we have just lived through. We can see this most clearly in the nations that have seen the biggest surges. Iran had 6 million people in 1915. It then suffered a famine that weakened everyone's immune system, so it was vulnerable when the 1918 "Spanish Flu" arrived. It had 5 million survivors by 1921. It now has 83 million people, an astounding increase of 1,660%. Before it can go any further, it will need to rethink all of its institutions, government, education, culture, and worklife. In the same way that a corporation needs to fundamentally re-think everything after a 10x shift, so too do nations. I've studied Iran, but I have not studied Africa, but I believe in Africa you can find similar stories, such as what has happened in Nigeria. I don't mean to suggest that population pressures are the only reasons why people might be wary to have children, I only mean this is something to keep in mind when we discuss this issue. The human population of the Earth has exploded over the last century and especially the last 60 years, in absolute terms. Having to absorb a big population surge can leave any country a bit disorganized. Consider the USA. The biggest generation ever, the Baby Boom, came of age between 1965 and 1987. Given the big surge of the working population, you might think these would have been years of exceptional economic growth. Instead, the opposite happened, these were the years of "The Great Stagnation" with falling wages and falling productivity. No doubt the Great Stagnation was a complex, multi-factor event, but it is interesting that it happened when a naive model might have predicted a big surge.