You may know about the Drake Equation, which is an attempt to quantify the number of intelligent species that evolve in a galaxy. Depending on how you set the parameters, the answer varies from “lots!” to “almost none.” The first answer leads to Fermi’s Paradox: Okay, if there are lots of aliens… where are they? So far we’ve seen no signs (pardon the reference).
If you read science fiction you may also be familiar with the idea of Ancient Alien Ancestors (AAA) who are now long gone leaving only a legend. Sometimes there are The Ancients (now long absent), the current Elder Races (powerful, not always wise, not always kind), and the Younger Races (which Earthlings invariably belong to).
But what if we are those Ancient Ancestors?