So they built cities on the coast, but not along river valleys? How did they feed the cities without agriculture? If they had agriculture, we’d see the selection process in the genetic history of the plants, and the geographic spread of plants, and again they’d definitely have colonised river valleys that are better suited to agriculture than the coast.

Then of course their tools and other artefacts would have been traded all over the place. Stone tools from 100k years ago and more got traded or carried thousands of miles and all we see are implements for the hunter gatherer lifestyle.

It doesn’t make any sense.

Also river vallies, but principally coasts.

For most of these cultures, "cities" did not exist, and even assuming they did, from the times of the first early-agricultural settlements, might have numbered a few thousand, perhaps tens of thousands of souls. With little transport, food was either sourced locally, or brought in on boats, rafts, or barges. Total collection areas for bulk goods of more than a few kilometers would be highly unlikely, though longer trade routes for rare materials (timber, metals, spices, hides) might have existed.

A principle relic of such settlements are their rubbish tips. Again, lack of transport meant that waste and filth were moved a few meters, for as long as the settlement existing -- decades, centuries, or millennia. In many places these are the principle evidence of early settlements, particularly shell mounds (shellfish are an easy, reliable, and sustaining prey), and can themselves measure several meters high and tens of meters across, particularly on otherwise flat aluvial or riparian landscapes.

You might want to read up on Doggerland: https://www.nationalgeographic.org/maps/doggerland/

The TLDR is that a huge low-lying basin of fertile land around what is now the British Isles was inundated at the end of the last interglacial. (What is now the North Sea/English Channel was one of those river valleys you alude to.) The British Isles today would have been the relatively cold, arid, mountainous uplands survivors migrated into when their fertile, low-lying territory got flooded out. Assuming population density in the chilly uplands (glaciers, remember!) was low, then you'd expect the frequency of surviving stone tools to be lower, reflecting that. People don't leave stuff lying around in places where people don't live!

I'm fully aware of doggerland, but so what? Given all of Africa and Eurasia, doggerland was a tiny benighted patch of lowland in a cold remote corner. I'm sure some people called it home, but I don't see any compelling reason to put a lost civilization on it 100k years ago.

There are plenty of very fertile, habitable areas in the same region that would have been just as attractive. So settlements? Sure. But surely a civilization is more than just a settlement?

The best places would have been deltas on the coast where you have an immense fish supply in the ocean and fresh water from the river.

Which is exactly https://en.m.wikipedia.org/wiki/Doggerland

Why wouldn't they have just moved their cities inland? This doesn't seem too plausible. Maybe I could see some village suffering from rapid advance and the village gets abandoned but sea level rise isn't instantaneous, so it's doubtful to have caused deaths.

Edit: https://commons.m.wikimedia.org/wiki/File:Post-Glacial_Sea_L...

This image shows the fastest sea level rose was around 15K years ago, which is pretty close to the Neolithic era. At it's fastest rate sea level was rising at 30 meters per 1000 years, or about 3 centimeters a year. Ok, that's a very slow moving train. It's pretty easy to get off the tracks before it hits you. Doubtful to have cause civilization decline especially when it lines up closer to the onset of agriculture.

I don't think we're talking about Atlantis here. We're talking about ruins being inundated. There is some tipping point where every society collapses, and those inland and upland we occasionally locate. Except that we're having a damned difficult time doing that in aggressively biologically active regions like swamps or rainforests.

Say you built your town on a 3% grade next to the water. That's 3 meters of descent for every 100 meters of distance. If sea level rises 50 meters, your town's ruins aren't just ~45 meters underwater, there's also almost a kilometer and a half out to sea. Nobody is looking there.

The last time this issue came up on HN, I googled and discovered that archaeologists definitely are looking at the right places underwater. It is relatively expensive to do so, but it's hard to imagine that they totally missed a bunch of huge civilizations.

See my post below where I link to actual data on sea level rise rate. The ice caps don't melt instantaneously there's not enough energy in one summer to do that. The fastest it ever rose was 3 cm a year during a 1000 year period. Even at 3 cm a year you can build new buildings on higher ground as the water advances and never lose a beat. Especially when we're talking an era when most homes were built out of bones and deerskin and maybe clay. Without metal they couldn't even chop wood but even wood buildings go up rather quickly. I just fail to see how we could believe our ancestors made it through several ice ages, mastered fire, avoided being eaten by saber tooth tigers and hunted wooly mammoths and populated the whole globe but failed to avert a 3cm a year sea level rise.

You're still arguing against something that no one else is.

You're viewing their arguments as "Water overtook their cities and they died because of it".

Their argument is that "They died out and then water overtook their cities".

Well if we're still talking about "advanced civilization" like Mesopotamia, I can definitely see climate change causing a gradual collapse. I still doubt it was possible to have a large city prior to metallurgy and agriculture. Maybe megafauna was abundant enough that it could support that but it seems like a stretch.

As far as I am aware, none of the civilizations in South and Central America ever had metallurgy.

Having a civilization and keeping civilization are two different things. Once humans are capable of thinking of it, it would happen over and over again. But when it fails, the survivors might have a sort of cultural PTSD comparable to the Sodom and Gomorrah story in the Bible. People might resist trying again for generations (also, how many places could you found a civilization in a world without sanitation, metallurgy or medicine?)

I think the claim is not that sea level rise caused civilizational collapse, but that sea level rise could have obscured many coastal cities (which presumably suffered run of the mill, non-watery deaths).

People have pulled artefacts off the seabed where Doggerland used to be (and still is, it's just under quite a lot of water). Mostly by accident: fishing sometimes fetches stuff up from down there.

> Why wouldn't they have just moved their cities inland?

That's a great question to ask of Venice, for example.

Venice of course, is 1500 years old and people still very much live there. It's also made of materials that are impossible to craft without metal. I said a village might be abandoned due to sea level rise, but it's unlikely to cause civilizational collapse. Highly, highly unlikely, since it moves sooo slooow.

With changing climate, entire regions which may have been formerly hospitable, were not. Settlements may have been small and largely ephemeral. And they're now flooded under 300' of water and miles out at sea.

As an example: the initial human settlement of the Americas likely followed sea routes along the North, Central, and South American coasts. The region near Santa Barbara and Los Angeles, with the Channel Islands, extended much further out to sea, with some of the islands being connected to land, others being only a short distance (rather than 20-30 miles) offshore.

Settlements along both the coast and shore -- the most viable parts of these regions -- would now be utterly flooded. There are few or no traces of the initial migrations, save for a few inland settlements and venturing / foraging parties, though later settlements may exist.

Much construction and many artefacts would be of earth, wood, hides, and plant fibres, most rotting or melting away under water. There are simply few surviving remains, and those which might exist are hard to find and access.

The climate change itself would have occurred over centuries, with multiple moves and resettlements, or disappearance of entire cities. It's rare for even preindustrial civilisations to endure at their peak for more than a few centuries.

Kinda puts the old religous flood stories in a different context eh? There were almost certainly costal communities who were consumed by rising sea levels the world over. Recent global flooding.

The most likely origin of the middle eastern religious “meme” of the flood (Noah etc) is Sumerian plain floods (Mesopotamia). In fact, the stories in Genesis are most likely the retelling of Sumerian technological achievements (farming, building and the concept of time and seasons).

The inundation of the Black Sea may have occurred during early human times and have been passed down through myths and sagas.

There are, of course, numerous other possible events, a synthesis, or even pure fabrication, as the basis.