By this point, technology would have become an intuitive art, and therefore, so the saying goes, indistinguishable from magic. Certain humans will have developed the hereditary talent, which could easily be accentuated by selective breeding, and likewise the human lifespan could be extended by certain rituals procedures, here called Longevity Training. Unfortunately, playing around with the laws of nature had some unintended consequences, resulting in the destruction of Earth. The Paravians could easily be Sufficiently Advanced Aliens who hold the key (whatever it may be) to the continued health of Athera, and therefore the leverage to strike a deal with the Fellowship to ensure the well-being of their world.