Nature has no use for anything that cannot reproduce abundantly.
Nature cares more about the species than the organism. That is why through the struggle of natural selection, quantity has been set as the prerequisite to quality – large litters, big families, the race of a thousand sperms.
Nature does not care that a high birth rate usually accompanies a lower culture or that a higher culture accompanies a higher birth rate.
Nature will make sure that in the end, no matter how hard it tries, the higher culture nation will age, and will be replaced with a more virile and fertile nation.