Why do so many ancient cultures have similar flood myths? Coincidence or shared history?

This has been doing my head in for years. You've got the Biblical flood narrative, you've got Mesopotamian flood stories, Aboriginal dreaming traditions describe floods, Native American tribes have similar myths, ancient Hindu texts describe massive floods... the list goes on.

Conventional explanation: Floods are common disasters, so cultures living near rivers would naturally develop flood mythology. Makes sense, right? Boring but sensible.

Alternative explanation: All these cultures witnessed and recorded an actual catastrophic global flood event at some point in prehistory. Maybe it was tied to the end of the last ice age? Maybe it was something else entirely? The specificity of some of these accounts is quite remarkable - specific details about animals, arks, survival narratives.

I'm not saying Atlantis was real or anything (well... maybe a little), but I'm curious whether anyone here has found connections between these myths that go deeper than just "water is scary." Are there linguistic similarities? Shared symbols? Or is this just pattern-matching on my part?

There actually was a catastrophic flood event at the end of the last ice age - it's called the Younger Dryas impact hypothesis, though there's still scientific debate about it. But the timeline makes it unlikely that humans from different continents would've shared stories about it in the way these myths suggest, given how scattered populations were.

That said, the recurring flood narrative is worth studying from a mythological perspective. It might be that floods just hit hard enough in human memory that they become spiritual/cultural touchstones. Doesn't mean the conventional explanation is wrong.

Have a look at "When the Sky Fell" by D.S. Allan and J.B. Delair. They argue for a cosmic collision around 9,600 BC that caused global catastrophe and the Ice Age's end. Not everyone accepts it (plenty of skeptics in academia), but the parallel myths are genuinely striking when you lay them all out together. Might give you some reading material to dig into.

I'm not saying Atlantis was real or anything (well... maybe a little)

Here's my take: Plato invented Atlantis as a philosophical thought experiment. Everyone knows this. But it might have been inspired by real events he'd heard about - the Minoan eruption, other ancient floods. Same way modern blockbusters are "inspired by true events" but are basically fiction. Doesn't mean there's a hidden global conspiracy, just means stories get passed around and mixed up.

The linguistic angle is interesting. Some researchers have found possible connections between flood narrative vocabulary in different ancient languages, though I can't remember the specific papers. Would be worth doing a university library search if you've got access. Most of this stuff requires proper academic sources to get anywhere.