Your idea that "behaviorally modern" humans are unnatural and alienated from nature is mistaken, it is natural, a part of nature. Maybe you don't mean "Nature" but wilderness and not "behaviorally modern" but "behaviorally tamed or unwild." The Empire State Building is just a very big anthill or termite mound and just as much a part of "Nature."

I am not much of a biologist but maybe there are examples of wild animals delaying reproduction until they are more mature and can better provide for their offspring. Maybe we don't know about this because it has not been studied.

TEK