I say this tongue-in-cheek, but there is always the Star Trek theory that intelligent life was seeded throughout the universe by intelligent beings. The idea was that they injected intelligent genetics into the residents of various planets. Which they used to explain why all of their aliens had similarities amongst them despite their origins.

That said, apparently the big change was when we added advanced communication to our repertoire some 40k years ago? We also began to practice religion at the same time. Go figure.