The economics might factor in a bit... but breeding rate and selection is, and always will be, controlled by the women. A prosperous male partner and high household income would actually enable the woman to be a stay-at-home and have more kids. However, we all know that is becoming more and more rare, due to both females educating themselves and higher standards of living which are now difficult to afford without dual parent incomes. The richest people are having the fewest kids on average; they have usually spent so long in school and working hard for job promotions that they have few fertile years left... or many people who were born rich want to enjoy life and just relax with few or no kids to slow them down. Homosexuality is also on the increase, and by making that choice, those men and women are likely to have no kids.It's simple economics. As we become more prosperous we have less need for large families.
Quite the opposite... yes, the immigrants will initially stick with their known ways in the new country. That will seem to work ok, even great, since they have increased resources and health care which may save some of their kids which would otherwise starve or get disease in the old country.Opening the borders of advanced countries to the third world will increase population growth exponentially unfortunately.
Quite the opposite... yes, the immigrants will initially stick with their known ways in the new country. That will seem to work ok, even great, since they have increased resources and health care which may save some of their kids which would otherwise starve or get disease in the old country.
...however, those immigrants will rapidly start to emulate the free and educated country's use of birth control. The kids will see they are a part of a big family... a big poor family. They will quickly realize that the path to prosperity lies in education and self development (especially learning the native language), not simply a numbers game to survive. You will be amazed at the rate that happens... typically just a generation or two.
It doesn't happen overnight, but they pay attention and learn pretty quick. The key is the womens' rights, educational opportunities, and access to birth control. It works wonders... even for the heathens. I agree that it has to be controlled inflow, though. You can't just remove all borders and immigration restrictions.

The issue is even much simpler than econ, though: it is common sense and knowledge. The best form of birth control is to educate the women.