It has been my pet theory that human civilizations had advanced a lot more before a some kind of extinction event pushed humans back to 1. Maybe not as technologically advanced as the current civilization but advanced in its own way.
It’s an entertaining idea, however unfortunately easily proven wrong. The most striking argument against it (or any “Silurian” theory) is that any form of “civilization” in the strictest sense needs permanent settlements that require permanent agriculture, and hence fertilized soil. We should hence be able to find nitrogen rich layers of soil or sediment where prehistoric civilizations resided, but that’s just not the case.
