Could Earth Have Hosted a Prehuman Techno-Civilization—and Could We Know?
Two scientists explore the 'Silurian hypothesis'—the idea that an advanced civilization could have lived on Earth millions of years ago and altered the planet’s climate. They assess how such a civilization might leave detectable traces in fossils, sediment chemistry, plastics, and metals, but conclude that most evidence would be erased by geologic time, making direct proof unlikely. The aim is not to confirm past civilizations but to outline what signs researchers would need to look for to test the idea and to reflect on humanity’s own long-term prospects amid climate change.