> the hypothesis postulates that previously a species different from ours had achieved high intelligence and technological civilization on this planet<p>An interesting special version of this hypothesis is that if a species has achieved truly high intelligence and advanced technology, it may <i>by design</i> not have left any traces. Not because of modesty but because long-term sustainable existence actually required being light on environmental impact.<p>Changing your environment at planetary scale and breakneck speed is not necessarily the pinnacle of intelligence, certainly not if you have manifestly not yet understood all its intricacies, interdependence etc. A lack of understanding coupled with aggressive random interventions may even affect the very survival of a species.<p>The downside of the deep-sea tree-huger cephalopod scenario is that it is even harder to falsify...
Surprised the article didn't mention the Paleocene–Eocene Thermal Maximum (PETM) [0] and it's interesting relation to "a species different from ours had achieved high intelligence and technological civilization on this planet."<p>For those unaware, the PETM was a rapid increasing in global temperature (and CO2 concentrations) around between 60-50 million years ago. This lead to a minor (on a geological time scale, major for those creatures living through it) climate crisis.<p>The cause for the rapid increase in temperatures at this time is still the subject of deep debate and largely unknown. However how very "out there" hypothesis, not even mentioned on the wikipedia page, is that this <i>could</i> have been when a civilization such as our experience an event more-or-less identical to our own current climate crisis caused by the rapid use of hydro-carbons.<p>Of course, the biggest challenge with this hypothesis is, as pointed out in the article, a civilization like this would not leave a trace on the geological record. So there's really no reasonable way to have much evidence in favor of this possible explanation.<p>But since here about this I've been fascinated by the problem of <i>sending messages</i> to the future. Suppose we come to realize that rapid use of hydrocarbons does most certainly lead to the destruction of any civilization foolish enough to tread this path. The most reasonable focus of scientific effort that would be to figure a way to warn the next advanced civilization on this planet in hopes they might not meet the same fate. But presuming that civilization is 50 million years in the future, how could this be done?<p>0. <a href="https://en.wikipedia.org/wiki/Paleocene%E2%80%93Eocene_Thermal_Maximum" rel="nofollow">https://en.wikipedia.org/wiki/Paleocene%E2%80%93Eocene_Therm...</a>
> <i>Reaching “only” the Neolithic stage could be described as a “Silurian hypothesis light”; it’s not highly significant achievement for a species, and even such a species can significantly turn over the planet’s fauna. Even our hunter-gathering (Paleolithic) ancestors hunted a number of large animal species to extinction (you don’t have to kill every last mammoth or giant bird to do that), and our farming ancestors (before the advent of even the simple most metal tools) caused massive modifications of the fauna and florae of extensive landscapes. Some of these faunal changes might be detectable millions of years into the future.</i><p>To be fair, a species can achieve that without any intelligence or civilization whatsoever if they just manage to grow their population enough.<p>I think the most extreme species in that regard would be cyanobacteria, which changed the composition of Earth's atmosphere from methane and CO2 to oxygen [1] - and subsequently caused the metabolism of almost all other species to become oxygen-based.<p>This change is not just "detectable" today, it became the basis of most life on the planet.<p>[1] <a href="https://asm.org/articles/2022/february/the-great-oxidation-event-how-cyanobacteria-change" rel="nofollow">https://asm.org/articles/2022/february/the-great-oxidation-e...</a>
Related discussion about a year ago <a href="https://news.ycombinator.com/item?id=38668884">https://news.ycombinator.com/item?id=38668884</a><p>And some threads from 2, 4, 5 and 7 years ago (did a pre-civilization discuss the possibility of a pre-pre-civilization?)<p><a href="https://news.ycombinator.com/item?id=34755970">https://news.ycombinator.com/item?id=34755970</a><p><a href="https://news.ycombinator.com/item?id=23654393">https://news.ycombinator.com/item?id=23654393</a><p><a href="https://news.ycombinator.com/item?id=21840320">https://news.ycombinator.com/item?id=21840320</a><p><a href="https://news.ycombinator.com/item?id=17899478">https://news.ycombinator.com/item?id=17899478</a>
Before bony fish ascended to their current dominance, there were plenty of other fast predators in the sea. If lack of predators is a requirement for cephalopod civilization, the window probably closes much earlier than the Cretaceous.<p>An alternative, possibly more optimistic (?) hypothesis: the first step of their civilization would be collective defense from large predators. Population concentrations would then make farming very advantageous. Yes, I'm more a scifi writer than biologist.
The author didn’t seem to address how cephalopods would be able to develop civilization without demonstrating a similar aptitude for highly coordinated complex social behavior or the transference of ideas (complex language). These both seem necessary for development of a complex civilization as ideas can improve and spread much faster than biological information. It’s somewhat ironic, considering the opening salvo was related to an improbable language hypothesis.
I often think that a more interesting question would be that if there were another civilisation here on earth <i>right now</i>, would we even recognise it as such?<p>We are terribly preoccupied with tool use and physical artefacts as a defining factor of intelligence - anthropocentrism is of course pretty much inevitable, even when we talk of cephalopods.
<i>The Silurian Hypothesis: Would it be possible to detect
an industrial civilization in the geological record?</i> (2019) <a href="https://arxiv.org/pdf/1804.03748" rel="nofollow">https://arxiv.org/pdf/1804.03748</a>
Primates first appeared around 65 million years ago.<p>The earliest dinosaurs arose over 200 million years ago.<p>Therefore, it is possible that by about 130 million years ago, the dinosaurs would have reached our level of development. They could have detected the oncoming asteroid, built space ships, and left this planet. All while mammals were barely getting started.<p>This extremely likely scientific theory is explored in Hibbett, MJ's "Dinosaur Planet"<p><a href="http://www.mjhibbett.co.uk/dinosaurplanet/nindex.php" rel="nofollow">http://www.mjhibbett.co.uk/dinosaurplanet/nindex.php</a>
> The proposition that this was the case, is what I consider the actual most interesting hypothesis most likely to be false<p>>Probably the esteemed reader has noticed by now that I am no true believer in the Silurian hypothesis, but I like to entertain it<p>This kind of speculation has always stimulated my imagination. Unfortunately, the era of "fact-check" and truthiness has spawned a class of professional debunkers. This creates space for opportunist trolls to take the contrarian position. At one point there were those who engaged in debates over flat-earth for the sake of honing rhetorical skills. Today adults crusade against these absurdities without the slightest inkling of self-irony. Flat-earth is typically used as a pejorative at HN.<p>We haven't entirely lost the ability to have stimulating conversations about Silurians, Atlanteans or other improbable fantasy scenarios, but the trend is approaching. It feels like an indictment of the pop-materialist world view, mass media control structures or just our current era of Internet. Perhaps other posters can point to the underlying causes.
Interesting hypothetical, though I would put my money on birds rather than cephalopods :)<p>Octopi have impressive intelligence, but they are missing many other ingredients likely required for the rise of civilization: Intelligent bird species have them beat on complex social behavior, proto-language, long lifespans and security against predators. I'd say they are about tied on dexterity (parrots can do very nifty things with their claws and beak). And being able to fly is surely a massive boon for exploring and colonizing the Earth's surface. If the chimps didn't make it, I think birds would have the next-best shot at building a high civilization.
> experimental chemistry and physics would be harder to pull off underwater<p>Amphibious octopuses?[1] In the widespread and connected shallow seas of a supercontinent world?<p>[1] BBC Earth <a href="https://www.youtube.com/watch?v=ebeNeQFUMa0" rel="nofollow">https://www.youtube.com/watch?v=ebeNeQFUMa0</a>
It’s occurred to me on occasion that the deposits of crude oil are the result of ancient garbage dumps filled with plastic which eventually broke down into the hydrocarbons that we’re burning/turning back into plastic.
The author's hypothetical octopus "civilization" lacks most of the characteristics we associate with civilization. He seems to assume that agriculture, in the sense of pastoralism, is the only criterion. If this is the case, then ants have been running aphid-farming civilizations for millions of years. Leaf-cutter ants have run fungus farms as well.<p>I wouldn't be at all surprised that octopi and many other animals have loose farming-like behaviors. This is a far cry from what we generally mean by civilization.<p>In particular, I believe the domestication of fire is the dividing line between humans and animals. This tool provides access to an enormous new source of energy, which opened a myriad of possibilities unavailable to animals. The tool use and motor skills needed to build, maintain, and use fire probably was a significant stimulus to human brain development.<p>Cephalopods, of course, would have no opportunity to master fire.
Relevant PBS Space time video. <a href="https://www.youtube.com/watch?v=vyEWLhOfLgQ" rel="nofollow">https://www.youtube.com/watch?v=vyEWLhOfLgQ</a><p>Apparently most of the tell tale signs of an industrial civilization would be very subtle and ambiguous (they could have other natural explanations) even if said civilization was only a few million years before ours.
Sometimes I like to think that these silurians stayed around, and decided to "civilize" us, not realizing that in the meantime we evolved intelligence that exceeds theirs beyond their comprehension.<p>So they forced their civilization upon us, which they presumably consider highly advanced, but to us, it's nothing but primitivism repulsive to a healthy human.
If maximal compute power is limited by available energy and (most) animals obtain energy by burning oxygen, how much compute power do cephalopods (or other marine animal, excluding cetaceans because they are cheating by breathing air) have available relative to humans (or any other air breathing animal)?
I think the main indicator of intelligent civilization would be burial sites and memorial monuments.<p>While 10s of millions of years of geological change would certainly make these hard to determine, an advanced civilization is likely to produce millions of these. Surely we would have come across some by now.
haven't read the paper, but how does "They conclude that no ruins of ancient football stadiums, highways or housing projects would survive geological time" square with the existence of fossils?
>Back then the conference organizers gave away funny, tongue-in-cheek awards (this would be inconceivable by now – humor!), and one of these awards was for the “most interesting hypothesis most likely to be false”. I thought this was a great award, honoring science which was daring, and which had just missed the mark by a bit.<p>I find this so sad, there is less and less place for humor in society to not offend anyone
> So, in their original paper, Schmidt & Frank didn’t actually voice belief in an ancient civilization, but pondered the question if and how it would be detectable. They conclude that no ruins of ancient football stadiums, highways or housing projects would survive geological time.<p>That's absurd. If modern housing can't survive geological time, then dinosaur fossils also can't survive it. But fossils can actually survive geological time. So housing can as well. So an ancient civilization would be visible in the geological record.