Why do flood myths appear in so many unrelated cultures?

The answer

Flood myths appear in at least 200 cultures worldwide, from the Mesopotamian Epic of Gilgamesh (the oldest written version, predating the biblical Noah story by over a millennium) to the Deucalion myth of Greece, the Manu story of Hinduism, and numerous Indigenous traditions across the Americas, Asia, and the Pacific. Several hypotheses explain this prevalence: rising sea levels at the end of the last Ice Age (around 10,000 BCE) inundated vast coastal areas where many early civilizations lived, creating shared cultural memories. Large rivers flood periodically, and catastrophic local floods may become mythologized over generations. Some researchers argue that the flooding of the Black Sea basin around 5600 BCE, which raised water levels by 150 meters, may have directly inspired Near Eastern flood narratives.