[quote=njtosd]
The question is, what would cause the disparity in child bearing in the first place? [/quote]
This is simple. The most powerful predictor of birth rates is education level of women. This is true around the world, irrespective of culture. This goes hand and hand with going from an agricultural setting to an urban one. In an agricultural environment more children were almost like “profit”. Just a 80 years ago most of the first world was living in an agricultural setting.
Observational studies have shown that this usually takes 1-2 generation removed from the countryside to set in. By the time you get to the second urban generation , family sizes decrease dramatically. You can see a perfect example of this in Western Europe, where native populations are now shrinking and have to be replaced with immigrant populations. As technology improved after WW2, less people were needed for farming and there was a mass migration to the cities. Now, two generations later, they have a negative growth rate.
This trend will increase across the planet. We are living in the first time in history where more people live in cities than in countries and the exodus to the cities is accelerating. As this continues, birth rates will continue to decline and ultimately , the population will level off and decline. Most estimates are at around 9 billion.
