Atlantis, Lemuria, Mu, and ancient alien cities buried under the Antarctic ice are standard fodder for many works by occultists and science fiction authors asking us and themselves whether over the hundreds of millions of years during which life could exist on the surface of our world. Now, scientists are starting to ask the same question. Is it possible that we’re not the first advanced society on this planet? And if so, how could we know? The answer wouldn’t just give us more perspective on our own origins, it could also help us find proof of alien life.