Comment by hliyan

Full article not accessible because of soft paywall, but: I feel we're surprised by these revelations because our current timeline of civilization is constructed using surviving artifacts and fossils, both of which are exception, not norm. The vast majority of evidence of ancient civilizations probably got completely buried. It's not outside the realm of possibility that there were early civilizations over 100,000 years old, whose artifacts have now been wiped away by plate tectonics and the ocean.