The standard model of human civilization places its origins around 5,000–6,000 years ago in Mesopotamia and Egypt. Before that: hunter-gatherers, simple tools, no cities. But this model has a significant blind spot — most of the world’s coastlines were underwater at the end of the last Ice Age.
Sea levels were roughly 120 meters lower during the Last Glacial Maximum than they are today. The land exposed by that lower sea level — coastal plains, river deltas, shallow continental shelves — is precisely where early human populations would have concentrated. It’s also precisely where we can’t easily excavate. Whatever settlements, ports, or structures existed on those coastlines are now beneath the ocean.
This doesn’t prove that advanced civilizations existed before the flood. But it does mean the absence of evidence is not evidence of absence. Underwater archaeology is in its infancy, and the few sites that have been investigated — like the submerged structures off the coast of India at Dwarka, or the underwater ruins near Yonaguni in Japan — raise more questions than they answer.
The lost civilization hypothesis, associated most popularly with researchers like Graham Hancock, argues that a sophisticated maritime culture existed before the Younger Dryas catastrophe and seeded the myths, architectural traditions, and astronomical knowledge found in early civilizations around the world.