If an advanced civilization had lived on Earth millions of years ago, powered themselves with energy and wiped themselves out, would we know? "We are pushing the planet into a new climate regime … we know this is true, right? - Everett CollectionThe reason Schmidt had been mulling the possibility of previous advanced civilizations on Earth was an event deep in the past. In their report, Frank and Schmidt go through the chain of possible evidence that might exist in support of a past advanced civilization. Advertisement AdvertisementZalasiewicz is comfortable ruling out the prior existence of the kind of advanced civilization we live in today — "energy-guzzling, manipulative, constructional, and producing waste in colossal quantities."