1. Natural selection has nothing to do the question. This is an issue of culture, not of genetics. You could easily have a situation where we globally had decli

1. Natural selection has nothing to do the question. This is an issue of culture, not of genetics. You could easily have a situation where we globally had declining birthrate. The interesting question is - why are birth rates for these populations falling? Is it purely a matter of wealth? 2. If you reduce Americans to the wealthiest subset, you'd see the same trend. Historically, if you reduced Americans to their non-Irish subset, you'd see the same thing, because the Irish were the poor immigrant group of the time. 3. Europe isn't a thing. Very few people even think of themselves as Europeans. Well, so far anyway. I hold out hope the EU will gain currency. What's important is still national identity, and European countries have survived waves of immigration before. 4. Agreed. This isn't a crisis until population levels dip quite a bit more. 5. Mormons, albanian muslims, and ultra-orthodox jews haven't reversed any trend. Their birthrates are (roughly) constant. It's everyone else whose birthrate declined.