>I believe John B. Calhoun had it right, but was ahead of his time. His experiments on rodent populations showed that given a population where all the rodent’s needs were met, but limited in space, the population would never stabilize. It would eventually completely collapse.
>I think modern cities cause people to cross over that point where their behavior changes and will eventually cause a human population collapse. This past generation has raised the living standards of billions of people, especially in Asia. But it has caused a massive demographic migration into cities. Asians now live in mega cities, in 30 story apartment buildings. Africa is now doing the same thing.
Space has nothing to do with it. Mexicans have no problems having 10 kids in a very small area.
The primary factor in the number of kids is how liberated a given group’s women are. Not very liberated = lots of kids. Highly liberated = very few kids. This is why immigrant populations who don’t let their daughters join the host culture like Muslims in England have very high birthrates compared to the locals.
Urbanization as well as development correlates with reduced fertility. Consider the state of Mexico, the country’s most populous political subdivision, with more than 14 million inhabitants. This state encompasses many of the poorer parts of Greater Mexico City, and thus has a per capita level of economic output substantially lower the national average ($8,900 for the country of Mexico vs. $6,200 for the state of Mexico, in nominal GDP). Yet the state’s birthrate is well below the national average, having been under the replacement level even in 2000
Mexico's birth rate, once among the world's highest, is in free-fall. In the 1960s Mexican mothers had nearly seven children each (whereas women in India then had fewer than six). The average now is just over two—almost the same as in the United States. The UN reckons that from 2040 the birth rate in Mexico will be the lower of the two.