Do you believe there are species that have mastered FTL travel?

[Xithras]

127. And yet...

...the natural reproductive rates among humans in the western world has largely fallen to replacement rates (or even below replacement rates) as technology, medicine, and societal pressures have eliminated the need to reproduce with abandon simply to produce genetic heirs. Most of the worlds population growth today comes from regions where that technology is not yet available or socially acceptable, and even in those areas we are beginning to see declines in birthrate. Among population groups immigrating into the western world where birthrates are already lower, there is a clear statistical drop in birthrate within a single generation of that families migration.

Most statisticians expect that the worlds population will stabilize within a few generations as these things become more widespread and accepted globally, and the only real question is whether that stabilization will occur before or after we exceed this planets sustainable carrying capacity.

In all probability, even humankind will achieve a stable population before we reach out into the stars and start looking at new Earth's. I don't see a technologically advanced species, human or otherwise, moving out into the stars after countless generations of "small families" and suddenly deciding "Woohoo, we can breed like rabbits now!" Once small families are normalized, and minus any actual direct benefit from having larger families, I don't see any reproductive benefit to reverting to the larger family size. In fact, as doing so would actually reduce resource availability to the already existing population, it's probable that societal pressure would continue to favor smaller families.