> the hypothesis postulates that previously a species different from ours had achieved high intelligence and technological civilization on this planet
An interesting special version of this hypothesis is that if a species has achieved truly high intelligence and advanced technology, it may by design not have left any traces. Not because of modesty but because long-term sustainable existence actually required being light on environmental impact.
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.
The downside of the deep-sea tree-huger cephalopod scenario is that it is even harder to falsify...
> 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.
Well apparently their strategy to ensure survival didn't do too well since we're discussing an extinct civilization here.
> Well apparently their strategy to ensure survival didn't do too well since we're discussing an extinct civilization here.
Maybe they're "extinct here", because they just left.
BTW. this is actually a big theme in David Brin's Uplift saga[0]. Basically, you have all these alien civilizations, more and less friendly to each other, but bound by some common rules, some of which regulate sustainable colonization. This includes an exclusive right to settle and use a habitable planet with a biosphere for $whatever number of millenia, and after that time, the civilization there is supposed to pack up and leave, fix environmental damage, and erase any trace of their existence, commonly achieved by dumping everything into the planet's subduction zones so it gets naturally recycled; after that, the planet is to lie fallow for ${some other number} of millenia, to give nature a chance at creating more biodiversity and stuff.
The problem I see with this scenario is: if you're a biological being, planets with a compatible biosphere are probably extremely rare. Just having a biosphere might not be sufficient, if the makeup of the atmosphere is poisonous to you or it's too hot or cold for the way your species evolved. So why would alien civilizations agree to such a thing instead of just adopting a planet and staying there? The whole premise seems to agree that the aliens are all biologically compatible with each other, despite evolving on different worlds. Perhaps they bio-engineer themselves each time they settle on a new world?
> So why would alien civilizations agree to such a thing instead of just adopting a planet and staying there?
I'm guessing you've not read them?
The gimmick of the series is that all sentient species were uplifted from non-sentient animals, and they were uplifted by species that were uplifted, which in turn were uplifted... and none of them knows by whom or by what. The "progenitors", the hypothesized first sentients that uplifted a presumed first generation, are lost to prehistory and nobody knows.
So there is a shared culture and a small degree of shared biology, because each generation of uplifters uses existing models of sentient species to model new sentient species. There are only so many ways to invent the wheel, although Brin was very imaginative indeed in this.
Humans were not uplifted; we're called "wolflings" and as a terrifying novel abomination would have been exterminated upon discovery, were it not for the novels' future setting having us already started work uplifting dolphins, chimpanzees, orang utans and a handful of other species. If humans were not a progenitor species the aliens would have extirpated us -- but we have client species of our own.
He does have answers to most of the objections one might come up with.
Brin's ideas were influenced by Larry Niven, and riffed upon by Terry Pratchett in his early SF works. Later Brin novels riff on ideas from his own earlier ones.
In their time, in the 1980s, I really enjoyed them. I own them all, several in hardback. I haven't re-read them in decades so I don't know how they hold up, but Brin is alive and still active.
In that galactic society, a races' power and prestige are measured by what client races that have "uplifted", taking species that naturally evolved on those fellow planets and then engineering then with intelligence and directing their society. (To some extent in the other direction too: A race might have powerful patrons or grandpatrons that are still around.)
Anyway, point is that for the kinds of races likely to get their manipulators on a fresh planet, direct colonization is often way down their list of priorities. (And perhaps most of their population is already in a Dyson swarm or something.)
Also, the deep history of visits means there's been time for a lot of similar biology to spread around.
it's a bit more involved than that, IIRC (been a while) - the civilisations involved typically migrate around the galaxy, entierly abandoning entire arms of the milky way and moving to another; agreements with other non-compatible civilisations mean that those that remain exist in an extremely hostile environment (the wars between the oxygen and hydrogen breathers, in particular, were notable until they managed to come to this arrangement).
There are also significant numbers of extremely agressive and militaristic civilisations, mostly held back by the laws and customs of setting, who would gleefully seek out and destroy anyone not following along.
>Well apparently their strategy to ensure survival didn't do too well since we're discussing an extinct civilization here.
Not necessarily. They could have existed hundreds of millions of years ago, and become victims of the Chixhulub asteroid impact or other huge natural disaster after successfully maintaining an advanced civilization for hundreds of thousands of years, FAR longer than our probably ill-fated civilization has managed. They might have also left the planet. Or they could have transcended into energy beings.
External factors are the obvious answer, the Earth and its planetary environment are actively evolving over geological scales.
Another intriguing possibility is some sort of senility setting in after long-term evolutionary success. The intelligent cephalopods eventually got tired seeking answers from a mysterious Universe and settled for the quite life.
"their strategy to ensure survival didn't do too well "
We aren't doing that well either. Too early to tell. But I think we've shown enough problems to at least speculate on how we will do during the coming 'great filters'.
That's the exact opposite of what de-growthers believe (though my experience has been that most 'de-growthers' are in fact imaginary straw men since I've only met people decrying them, none truly espousing these beliefs as a strategy).
The beliefs described by the parent are basically the de facto beliefs of everyone who believes the climate crisis can be solved through some form of accelerationism.
I don't think there's even a question that the only proven method of reducing emissions and slowing climate change is to leave fossil fuels in the ground (which is by definition de-growth in practice). But there has never been any remotely serious will for actions of this nature.
What you actually have to "prove" is that you can pass/execute the laws required to "leave the fossil fuels in the ground".
All evidence thus far is that it's not happening, no one even votes for that under democracies.
So far, all evidence is that we can pass laws, create engineering, and cause behavior change that leads to reducing carbon emissions without hurting growth.
If you care about reducing carbon, the strategy of "destroy capitalism first" isn't going to happen at all, and especially not soon enough to have the impact you want.
Parent comment does not say that their preffered, nonetheless the only way to "leave the fossil fuels in the ground" is to pass laws mandating that, nor that they favor a "destroy capitalism first" approach. Leaving fossil fuels in the ground by say encouraging the adoption of another energy source like solar has thus far been a successful strategy.
The people publishing books using the term "degrowth" (Jason Hickel, etc.) do call for destroying capitalism and believe fighting for climate change isn't compatible with growth.
Green growth people (like myself) argue that we can grow without incurring the negative carbon impacts given proper policy / tech.
We very much want solar, etc. technologies that do this. Degrowth isn't the solution.
A theory about a previous advanced civilization must first and foremost explain how and why it skipped using all the obvious under-your-feet materials and fuel sources in its initial phase.
And taking it even further, maybe they still exist, but have advanced so far they are undetectable to our simple minds and senses, similar to how an ant or bacteria has no idea about our existence. Maybe there are millions of advanced species that we can't detect, considering that there are millions of species we are aware of, and statistically it's unlikely that we would be the most advanced.
That's actually a factor that diseases aim for. Mortal diseases don't spread as much as the ones that don't damage the host as much. Because of this, severe diseases sometimes evolve into mild ones.
> 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.
To be fair, a species can achieve that without any intelligence or civilization whatsoever if they just manage to grow their population enough.
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.
This change is not just "detectable" today, it became the basis of most life on the planet.
Another one is the Azolla event hypothesis where a variety of fern grew so much that as it died and sank to the ocean it sequestered massive amounts of carbon, enough to alter the climate.
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."
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.
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 could 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.
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.
But since here about this I've been fascinated by the problem of sending messages 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?
Some ideas for sending messages to the next civilization.
1. Genetically modify as many wild plants and animals as we can to have a message encoded in their DNA, and release them back into the wild.
2. In areas that we expect to be geologically not much changed over the next 50 million years arrange concentrations of long lived radioactive materials in patterns that are obviously not natural. Encode a message in those patterns.
3. We could probably do something on the moon with nuclear weapons that could make a long fairly straight trench or series of parallel trenches that would be visible in telescopes and either be obviously non-natural or at least interesting enough to get them to go take a look.
Leave millions of metal spheres, cubes, tetrahedrons, octahedrons, dodecahedrons, and icosahedrons there which contain messages inside.
Google is telling me that any given spot on the moon gets hit be a meteoroid of ping pong ball size or greater about every 1000 years, so many of the messages will likely be destroyed over 50 million years, but maybe enough will make it.
BTW, is meteoroid the correct term? That's what Google's summary used and according to the dictionary definition as a small body that would become a meteor if it entered the Earth's atmosphere it would be correct but when we are talking about impacts on other planets or moons I'm not sure we should restrict meteor and meteorite to just meteoroids that are in or have hit after passing through Earth's atmosphere, respectively.
> a rapid increasing in global temperature (and CO2 concentrations) around between 60-50 million years ago
> a civilization like this would not leave a trace on the geological record
Am curious: if dinosaurs can be found with intact skin [1], after 110 million years, why not remains of the civilization's "people" (bones etc.) after 60-50 million years?
If PETM was due to large scale use of hydrocarbons, there should be evidence of depletion in the strata, right? For example, currently not all sources are uniformly exploited -- some coal seams and oilfields are all but depleted, others are currently being extracted, and others are yet to be found/exploited.
We should have seen signs of similar non-uniform usage in the strata from before that time period. I wonder if any research has been done on this.
Has someone done the math on what Hydrocarbons (coil, oil) would have been available 60 million years ago?
Would they have been using the same deposits we are suing, or would new deposits have formed over the last 60 million years?
Or could they have depleted their own, but what was un-usable 60 million years ago, have become usable today. Like something that was marsh land 60 million years ago, be coal today?
> current climate crisis caused by the rapid use of hydro-carbons.
The problem I see is they either had to use sustainable hydrocarbons (so, carbon-neutral) or they would have used up the fossil fuels we're currently using.
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.
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.
It could be as simple as the evolution of fish jaws making the mollusc shell insufficient defense. Or fish eyes/pressure sense/etc developing enough to notice hiding molluscs better. It's plausible that earlier predators were below the threshold of extinction-level risk. Flipping the perspective, humans were below an extinction-level risk for most large land animals for a long time.
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.
Despite being mollusks, like clams and oysters, these animals have very large brains and exhibit a curious, enigmatic intelligence.
I followed them through the sea, and also began reading about them, and one of the first things I learned came as a shock: They have extremely short lives — just one or two years.
Humans do seem to have some the longest life spans on the planet, and that's an important adaptation -- "grandmother hypothesis" and all that. I can see that generational knowledge is big deal, even in my own family, and in my coworkers' families.
Or you can look at the family of (ironically) Charles Darwin, with Francis Galton, and so forth
The outliers among primates move the civilization forward. So just having a few people with big brains, who absorb knowledge from their predecessors, is a big deal.
Though of course there could be some cephalopod species that evolved to live 100 years ... and then for some reason they disappeared, or lost that adaptation
One point to note is that humans evolved from apes at a quick pace. I've heard claims that longer life-span, the ability to engage in complex vocalizations, opposable thumbs, upright stance, binocular vision and so-forth are all pretty recent innovation over evolutionary short period, with large brain size turning out to be last addition.
The human package might be not much more complex than "start with a rock-throwing mob and features providing benefits"
So, on the surface, you could have a species that sprinted to all the features required for civilization - and then destroyed itself in a blaze of less-than-glory as we seem on a trajectory to do.
Edit: Note, I should add that I'd actually doubt this scenario could happen only because the evolution of human seems part of the general acceleration of evolution that can be seen throughout geological history.
There is discussion in the article about cephalopod communication, and how they use complex patterning and physical movement to communicate with each other. Is their level of communication and their information transfer speed as high as language? I don't think we can know very well without asking a cephalopod.
Now, that whole section is talking about modern cuttlefish, so I would agree with you regarding the author's hypothetical nautilus civilization.
The cephalopods we observe today would be many millions of years removed from the Silurian cephalopods. It would be like trying to gauge the language capabilities of humans from observing squirrels.
Memorized inherited tacit knowledge around campfires may had been our own specie's cultural medium, but other ways (with slower bitrate) can easily be entertained.
Vocalizations and their evolution were banned from discussion in the Royal Society because they did not leave a fossil record, so even meta-science was harder back then.
As for knowledge transfer, we know that they can teach other how to perform certain tasks. But beyond that, there seems to be a lack of research. Do they have complex language and can they transfer abstract “ideas”? My guess would be yes, but they communicate through color changes in ways that we have a hard time understanding. It seems likely that birds and whales have complex language, but we haven’t cracked the code on that even though their communication is much more like ours. Hopefully we find out some day.
I often think that a more interesting question would be that if there were another civilisation here on earth right now, would we even recognise it as such?
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.
> We are terribly preoccupied with tool use and physical artefacts as a defining factor of intelligence
In the context of civilisation, intelligence isn’t enough. Nomadic tribes are sapient, intelligent and have rich cultures, but they aren’t strictly civilisations.
The urban distinction is important because of economies of scale: pastoral societies are energy constrained. That doesn’t make them less interesting, again strictly speaking, personally it sort of does, but it does make them less powerful.
Within the Silurian context, the urban distinction is almost demanding: if humans stopped at Neolithic pastoralism, there is a good chance all evidence of our tool use would have disappeared within a few millennia, let alone millions of years.
Maybe but it's also because these things are evidence of cultural transmission - a thing for which there hasn't been strong evidence of in other species and people do look for it in other ways.
When talking about aliens people often use the word "civilisation" to mean just "intelligence" and perhaps that's what you're doing because you're thinking about something that doesn't resemble a human civilisation. I agree with you that an alien intelligence might be very different from a human civilisation. Also, an alien intelligence might not even qualify as a form of life (it might be an artificial intelligence).
our senses are only equipped to experience small subsets of the whole - there's a huge range of sounds impercetible to human ears, our eyes can only perceive light in the visible spectrum, a dog's nose can detect orders of magnitude more information than a human's.
if the five senses can only percieve a fraction of that which they have been honed for over millennia, it's not unreasonable to wonder if there is much more to the world/earth than meets the eye, inaccessible and unintelligible to physical ape life or existing in ways we aren't equipped to percieve.
Interesting hypothetical, though I would put my money on birds rather than cephalopods :)
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.
Primates first appeared around 65 million years ago.
The earliest dinosaurs arose over 200 million years ago.
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.
This extremely likely scientific theory is explored in Hibbett, MJ's "Dinosaur Planet"
> The proposition that this was the case, is what I consider the actual most interesting hypothesis most likely to be false
>Probably the esteemed reader has noticed by now that I am no true believer in the Silurian hypothesis, but I like to entertain it
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.
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.
> Unfortunately, the era of "fact-check" and truthiness has spawned a class of professional debunkers.
This is a reaction to the “alternative facts” and the waves of general bullshit.
> At one point there were those who engaged in debates over flat-earth for the sake of honing rhetorical skills.
It’s one thing to engage in debates with your mates; it’s another to be subjected to a constant barrage of misinformation. Also, a couple of my mates from the “just asking rhetorical questions” period went full conspiracy theorists after a decade or so. I am less and less inclined to think that they were playing the devil’s advocates even back then.
> Flat-earth is typically used as a pejorative at HN.
Well, yeah. It’s the dumbest, most falsifiable of the stupid conspiracy theories, mixed in with a solid dose of religious fundamentalist. It’s not just games, at least not for everyone. Far too many people take it seriously, so it is unreasonable to act like it’s all fun and games.
Conspiracy theory is a self-reinforcing loop and people primed for this sort of thing do jump onto the next one without much critical thinking.
> We haven't entirely lost the ability to have stimulating conversations about Silurians, Atlanteans or other improbable fantasy scenarios, but the trend is approaching.
Fantasy is fantasy. This is not it. If you want to write a book about whatever thing you can think of, then have at it. The problem is when a fairy tale about aliens becomes gospel. So, if you don’t want to be debunked, don’t present fantasies as established facts.
> Today adults crusade against these absurdities without the slightest inkling of self-irony.
> Perhaps other posters can point to the underlying causes.
It's because a lot of the flat-earthers out there on the internet actually believe it. It's no longer an amusing discourse, fun little game or intellectual pursuit for the high-minded playful contrarian, it has transitioned to an actual conspiracy theory with actual adherents.
> Flat-earth is typically used as a pejorative at HN.
As it should be, given the above. It has become part of the wider conspiracy-sphere alongside chemtrails, 9/11 'truth' and all the other crap. It's no longer a sign of high intelligence or curiosity when someone brings it up, if it ever was.
Compare "BirdsArentReal", though honestly I expect that eventually to go the same way.
> At one point there were those who engaged in debates over flat-earth for the sake of honing rhetorical skills.
Do you have any proof that modern flat earthers were ever anything but a silly conspiracy group? The history I know of is of bizarre little flat earth cult groups denying basic science like this, and people outside their bubbles being amazed that they are not being sarcastic when encountering them in the wild.
Denying basic knowledge known since the ancient greeks or earlier is absurd to engage with.
And now I'm just sitting here imagining tentacles rising up from a puddle, holding a tightly wrapped fish-skin container, to do an experiment in the air.
Maybe they'd think of "going into the air" like early human chemists think of donning protective aprons. Air keeps the chemicals from getting on your skin.
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.
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.
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.
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.
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.
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.
Cephalopods, of course, would have no opportunity to master fire.
It's not any particular technical development that separates humans from other animals, but the human relationship to technology as such. Humans only live by way of inserting external objects between themselves and nature, and they do this in an open-ended way. One could also talk about human self-domestication, and agriculture as a self-expanding ecosystem... Fire doesn't really capture the way humans actively modify their own conditions of life.
Why fire? Why is that so different from other tools that require significant effort to create?
Some animals use some tools, but mostly just sticks IIRC, with no effort to creating them, beyond breaking one off a tree.
Maybe the criterion 'spend a lot of effort to create a tool' is the criterion, since having the time to spend on tool making requires someone else to get food for you etc. so is that getting towards a civilization?
>In particular, I believe the domestication of fire is the dividing line between humans and animals.
Must there be only 1 line? To me, language is another important one as it greatly increases the efficiency that one can communicate information generation to generation and it seems to have an impact on how we think. Children raised without exposure to language seem to suffer developmental issues, though this isn't well studied given the ethical issues involved in such a study.
As to how much communication is needed to count as a language, that is much harder to draw a definite line given that other species do communicate, but we don't consider them to have a language.
We don't even know when humans domesticated fire, though it certainly long predates the rise of civilization by any reasonable definition.
Certainly fire was a killer app for early hominids, but it doesn't mean it is a necessary step, nonetheless the necessary step on the road to intelligence.
The LAGEOS satellites, which are in an extremely stable orbit and made from dense materials that should maximize their stability, are expected to re-enter Earth's atmosphere in 8.4 million years.
I think the main indicator of intelligent civilization would be burial sites and memorial monuments.
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.
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)?
An adult human at rest breathes about 500mL air per breath, at about 12 breaths per minute. The inhaled air is about 21% O2, and the exhaled air is about 16% O2.
The density of air is 1.225 kg/m3, which is 1.225 g/liter. So 5% of a half-liter breath is, ballpark, 0.03 grams oxygen per breath, which at one breath per five seconds is 0.006 grams oxygen per second.
Dissolved oxygen in ocean water is about 0.008 g/liter. Fish are very efficient at extracting this, up to 80%. Squids and octopi are much less efficient, with octopi hanging out more in the 40% range, and squids much lower.
So this means that for every liter of water processed, an example octopus receives 0.003 grams oxygen, and if such an octopus were able to process two liters of water per second across their gills, they would receive as much O2 as a human.
This is not such an incredibly high number that it rules out cephalopod intelligence, especially when considering size differences.
to save any interested parties a search: groups of 10-15 octopi have been dubbed 'octlantis' and 'octopolis' after being discovered off the coast of Australia. this is remarkable because octopi (including gloomy octopi) were previously thought to be largely solitary creatures which only interact when mating. octlantis features social hierarchies, disputes, and dens fashioned out of the shells of their prey which the creatures have been recorded evicting each other from. interesting stuff
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?
I haven't read the paper either but billions upon billions of organisms constantly have some tiny chance of ending up in the conditions where they fossilize and could later be found. A few thousand or million exposed structures over the few-thousand-year lifetime of a civilization is, in comparison, a microscopically smaller chance of preservation. Nature, in contrast, gets effectively infinite shots at this, the fossils record still has gaps that dwarf the lifespan of human civilization as it is.
> 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?
Broadly speaking, fossils are rare and we site our cities on river deltas and such which have bad conditions for them.
Perhaps it's down to scale? If a single relief of a single building block survives, is that still considered a ruin of a football stadium, or just an imprint of a building block? The Colosseum would certainly not be able to survive for 100 million years. If some intelligent beings find a single building block while doing archaeology, they'll likely not be able to recognize it's purpose, if they even recognize the building block for what it is.
The structural integrity of (comparatively) smaller fossils is much more likely to survive for 100s of millions of years. A large building will be eroded by roots, wind, acid rain, etc. A fist sized rock containing the imprint of a trilobite, buried in soil and safe from most elements, will easily survive for 100s of millions of years.
Or perhaps the author meant that the vast majority of our buildings are not built to last. An asphalt highway - if unmaintained - will be unrecognizable in a hundred years. Roman roads survived for a few 1000 years because of their very crude nature: they are just a pile of rocks. But even such structures will fall prey to soil erosion and the relentless assault of nature. Unless said roads see foot traffic, they'd be also quickly overrun by trees and grasses.
It's a numbers game. The stadiums, highways, etc. are very few and are being built during a blink of history, compared to fossils which typically come from animals that were around for tens or even hundreds of millions of years. The sheer number of creatures that lived and died means we've had a few lucky pieces preserved.
Earth's surface isn't very static. On a geological timescale it is constantly moving and churning.
>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.
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.
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.
> the hypothesis postulates that previously a species different from ours had achieved high intelligence and technological civilization on this planet
An interesting special version of this hypothesis is that if a species has achieved truly high intelligence and advanced technology, it may by design not have left any traces. Not because of modesty but because long-term sustainable existence actually required being light on environmental impact.
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.
The downside of the deep-sea tree-huger cephalopod scenario is that it is even harder to falsify...
> 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.
Well apparently their strategy to ensure survival didn't do too well since we're discussing an extinct civilization here.
> Well apparently their strategy to ensure survival didn't do too well since we're discussing an extinct civilization here.
Maybe they're "extinct here", because they just left.
BTW. this is actually a big theme in David Brin's Uplift saga[0]. Basically, you have all these alien civilizations, more and less friendly to each other, but bound by some common rules, some of which regulate sustainable colonization. This includes an exclusive right to settle and use a habitable planet with a biosphere for $whatever number of millenia, and after that time, the civilization there is supposed to pack up and leave, fix environmental damage, and erase any trace of their existence, commonly achieved by dumping everything into the planet's subduction zones so it gets naturally recycled; after that, the planet is to lie fallow for ${some other number} of millenia, to give nature a chance at creating more biodiversity and stuff.
Quite ingenious setting, if you ask me.
--
[0] - https://en.wikipedia.org/wiki/Uplift_Universe
The problem I see with this scenario is: if you're a biological being, planets with a compatible biosphere are probably extremely rare. Just having a biosphere might not be sufficient, if the makeup of the atmosphere is poisonous to you or it's too hot or cold for the way your species evolved. So why would alien civilizations agree to such a thing instead of just adopting a planet and staying there? The whole premise seems to agree that the aliens are all biologically compatible with each other, despite evolving on different worlds. Perhaps they bio-engineer themselves each time they settle on a new world?
> So why would alien civilizations agree to such a thing instead of just adopting a planet and staying there?
I'm guessing you've not read them?
The gimmick of the series is that all sentient species were uplifted from non-sentient animals, and they were uplifted by species that were uplifted, which in turn were uplifted... and none of them knows by whom or by what. The "progenitors", the hypothesized first sentients that uplifted a presumed first generation, are lost to prehistory and nobody knows.
So there is a shared culture and a small degree of shared biology, because each generation of uplifters uses existing models of sentient species to model new sentient species. There are only so many ways to invent the wheel, although Brin was very imaginative indeed in this.
Humans were not uplifted; we're called "wolflings" and as a terrifying novel abomination would have been exterminated upon discovery, were it not for the novels' future setting having us already started work uplifting dolphins, chimpanzees, orang utans and a handful of other species. If humans were not a progenitor species the aliens would have extirpated us -- but we have client species of our own.
He does have answers to most of the objections one might come up with.
Brin's ideas were influenced by Larry Niven, and riffed upon by Terry Pratchett in his early SF works. Later Brin novels riff on ideas from his own earlier ones.
In their time, in the 1980s, I really enjoyed them. I own them all, several in hardback. I haven't re-read them in decades so I don't know how they hold up, but Brin is alive and still active.
In that galactic society, a races' power and prestige are measured by what client races that have "uplifted", taking species that naturally evolved on those fellow planets and then engineering then with intelligence and directing their society. (To some extent in the other direction too: A race might have powerful patrons or grandpatrons that are still around.)
Anyway, point is that for the kinds of races likely to get their manipulators on a fresh planet, direct colonization is often way down their list of priorities. (And perhaps most of their population is already in a Dyson swarm or something.)
Also, the deep history of visits means there's been time for a lot of similar biology to spread around.
it's a bit more involved than that, IIRC (been a while) - the civilisations involved typically migrate around the galaxy, entierly abandoning entire arms of the milky way and moving to another; agreements with other non-compatible civilisations mean that those that remain exist in an extremely hostile environment (the wars between the oxygen and hydrogen breathers, in particular, were notable until they managed to come to this arrangement).
There are also significant numbers of extremely agressive and militaristic civilisations, mostly held back by the laws and customs of setting, who would gleefully seek out and destroy anyone not following along.
We’re talking millions of years. Maybe they’re post-biological.
>Well apparently their strategy to ensure survival didn't do too well since we're discussing an extinct civilization here.
Not necessarily. They could have existed hundreds of millions of years ago, and become victims of the Chixhulub asteroid impact or other huge natural disaster after successfully maintaining an advanced civilization for hundreds of thousands of years, FAR longer than our probably ill-fated civilization has managed. They might have also left the planet. Or they could have transcended into energy beings.
A strategy for avoiding one particular death is not a strategy to ensure survival.
There are >1 ways for a civilization to become extinct.
External factors are the obvious answer, the Earth and its planetary environment are actively evolving over geological scales.
Another intriguing possibility is some sort of senility setting in after long-term evolutionary success. The intelligent cephalopods eventually got tired seeking answers from a mysterious Universe and settled for the quite life.
"their strategy to ensure survival didn't do too well "
We aren't doing that well either. Too early to tell. But I think we've shown enough problems to at least speculate on how we will do during the coming 'great filters'.
South Park subtitle:
"This is what de-growthers actually believe."
That's the exact opposite of what de-growthers believe (though my experience has been that most 'de-growthers' are in fact imaginary straw men since I've only met people decrying them, none truly espousing these beliefs as a strategy).
The beliefs described by the parent are basically the de facto beliefs of everyone who believes the climate crisis can be solved through some form of accelerationism.
I don't think there's even a question that the only proven method of reducing emissions and slowing climate change is to leave fossil fuels in the ground (which is by definition de-growth in practice). But there has never been any remotely serious will for actions of this nature.
What you actually have to "prove" is that you can pass/execute the laws required to "leave the fossil fuels in the ground".
All evidence thus far is that it's not happening, no one even votes for that under democracies.
So far, all evidence is that we can pass laws, create engineering, and cause behavior change that leads to reducing carbon emissions without hurting growth.
If you care about reducing carbon, the strategy of "destroy capitalism first" isn't going to happen at all, and especially not soon enough to have the impact you want.
Parent comment does not say that their preffered, nonetheless the only way to "leave the fossil fuels in the ground" is to pass laws mandating that, nor that they favor a "destroy capitalism first" approach. Leaving fossil fuels in the ground by say encouraging the adoption of another energy source like solar has thus far been a successful strategy.
The people publishing books using the term "degrowth" (Jason Hickel, etc.) do call for destroying capitalism and believe fighting for climate change isn't compatible with growth.
Green growth people (like myself) argue that we can grow without incurring the negative carbon impacts given proper policy / tech.
We very much want solar, etc. technologies that do this. Degrowth isn't the solution.
Of course, we do have tree hugging octopus today: Save the Pacific Northwest Tree Octopus! https://zapatopi.net/treeoctopus/ (j/k)
A theory about a previous advanced civilization must first and foremost explain how and why it skipped using all the obvious under-your-feet materials and fuel sources in its initial phase.
And taking it even further, maybe they still exist, but have advanced so far they are undetectable to our simple minds and senses, similar to how an ant or bacteria has no idea about our existence. Maybe there are millions of advanced species that we can't detect, considering that there are millions of species we are aware of, and statistically it's unlikely that we would be the most advanced.
That's actually a factor that diseases aim for. Mortal diseases don't spread as much as the ones that don't damage the host as much. Because of this, severe diseases sometimes evolve into mild ones.
> 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.
To be fair, a species can achieve that without any intelligence or civilization whatsoever if they just manage to grow their population enough.
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.
This change is not just "detectable" today, it became the basis of most life on the planet.
[1] https://asm.org/articles/2022/february/the-great-oxidation-e...
Another one is the Azolla event hypothesis where a variety of fern grew so much that as it died and sank to the ocean it sequestered massive amounts of carbon, enough to alter the climate.
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."
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.
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 could 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.
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.
But since here about this I've been fascinated by the problem of sending messages 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?
0. https://en.wikipedia.org/wiki/Paleocene%E2%80%93Eocene_Therm...
Some ideas for sending messages to the next civilization.
1. Genetically modify as many wild plants and animals as we can to have a message encoded in their DNA, and release them back into the wild.
2. In areas that we expect to be geologically not much changed over the next 50 million years arrange concentrations of long lived radioactive materials in patterns that are obviously not natural. Encode a message in those patterns.
3. We could probably do something on the moon with nuclear weapons that could make a long fairly straight trench or series of parallel trenches that would be visible in telescopes and either be obviously non-natural or at least interesting enough to get them to go take a look.
Leave millions of metal spheres, cubes, tetrahedrons, octahedrons, dodecahedrons, and icosahedrons there which contain messages inside.
Google is telling me that any given spot on the moon gets hit be a meteoroid of ping pong ball size or greater about every 1000 years, so many of the messages will likely be destroyed over 50 million years, but maybe enough will make it.
BTW, is meteoroid the correct term? That's what Google's summary used and according to the dictionary definition as a small body that would become a meteor if it entered the Earth's atmosphere it would be correct but when we are talking about impacts on other planets or moons I'm not sure we should restrict meteor and meteorite to just meteoroids that are in or have hit after passing through Earth's atmosphere, respectively.
> a rapid increasing in global temperature (and CO2 concentrations) around between 60-50 million years ago
> a civilization like this would not leave a trace on the geological record
Am curious: if dinosaurs can be found with intact skin [1], after 110 million years, why not remains of the civilization's "people" (bones etc.) after 60-50 million years?
1. https://en.wikipedia.org/wiki/Borealopelta
If PETM was due to large scale use of hydrocarbons, there should be evidence of depletion in the strata, right? For example, currently not all sources are uniformly exploited -- some coal seams and oilfields are all but depleted, others are currently being extracted, and others are yet to be found/exploited.
We should have seen signs of similar non-uniform usage in the strata from before that time period. I wonder if any research has been done on this.
Has someone done the math on what Hydrocarbons (coil, oil) would have been available 60 million years ago?
Would they have been using the same deposits we are suing, or would new deposits have formed over the last 60 million years?
Or could they have depleted their own, but what was un-usable 60 million years ago, have become usable today. Like something that was marsh land 60 million years ago, be coal today?
I think the only option is to leave several copies of the message on the moon, and hope they stumble upon a copy.
> current climate crisis caused by the rapid use of hydro-carbons.
The problem I see is they either had to use sustainable hydrocarbons (so, carbon-neutral) or they would have used up the fossil fuels we're currently using.
Send it to space. To multiple places. Next guys should be able to find it sooner or later.
> a civilization like this would not leave a trace on the geological record.
At all? Like nothing that would be observable 50M years later?
Put up a plaque reading "This is not a place of honor ..." ?
Related discussion about a year ago https://news.ycombinator.com/item?id=38668884
And some threads from 2, 4, 5 and 7 years ago (did a pre-civilization discuss the possibility of a pre-pre-civilization?)
https://news.ycombinator.com/item?id=34755970
https://news.ycombinator.com/item?id=23654393
https://news.ycombinator.com/item?id=21840320
https://news.ycombinator.com/item?id=17899478
Thanks! Macroexpanded:
Possible to detect an industrial civilization in geological record? (2018) - https://news.ycombinator.com/item?id=38668884 - Dec 2023 (187 comments)
Silurian Hypothesis - https://news.ycombinator.com/item?id=34755970 - Feb 2023 (60 comments)
Did Advanced Civilizations Exist Before Humans? Silurian Hypothesis [video] - https://news.ycombinator.com/item?id=32837757 - Sept 2022 (1 comment)
Silurian Hypothesis: Were There Civilizations on Earth Before Humans? (2018) - https://news.ycombinator.com/item?id=23654393 - June 2020 (138 comments)
The Silurian Hypothesis - https://news.ycombinator.com/item?id=21840320 - Dec 2019 (52 comments)
Silurian hypothesis - https://news.ycombinator.com/item?id=17899478 - Sept 2018 (7 comments)
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.
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.
It could be as simple as the evolution of fish jaws making the mollusc shell insufficient defense. Or fish eyes/pressure sense/etc developing enough to notice hiding molluscs better. It's plausible that earlier predators were below the threshold of extinction-level risk. Flipping the perspective, humans were below an extinction-level risk for most large land animals for a long time.
The presence of fast predators on land certainly didn't prevent us from evolving.
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 read somewhere that cephalopods are kind of like "individual flashes of genius".
They develop large brains very rapidly, with lots of skills, BUT they don't pass on their skills, in part because they die quickly!
This article mentions that:
https://www.nytimes.com/2016/12/02/opinion/sunday/octopuses-...
Despite being mollusks, like clams and oysters, these animals have very large brains and exhibit a curious, enigmatic intelligence.
I followed them through the sea, and also began reading about them, and one of the first things I learned came as a shock: They have extremely short lives — just one or two years.
Other discussion - https://tonmo.com/threads/why-dont-octopus-and-other-cephlap...
---
Humans do seem to have some the longest life spans on the planet, and that's an important adaptation -- "grandmother hypothesis" and all that. I can see that generational knowledge is big deal, even in my own family, and in my coworkers' families.
Or you can look at the family of (ironically) Charles Darwin, with Francis Galton, and so forth
The outliers among primates move the civilization forward. So just having a few people with big brains, who absorb knowledge from their predecessors, is a big deal.
Though of course there could be some cephalopod species that evolved to live 100 years ... and then for some reason they disappeared, or lost that adaptation
One point to note is that humans evolved from apes at a quick pace. I've heard claims that longer life-span, the ability to engage in complex vocalizations, opposable thumbs, upright stance, binocular vision and so-forth are all pretty recent innovation over evolutionary short period, with large brain size turning out to be last addition.
The human package might be not much more complex than "start with a rock-throwing mob and features providing benefits"
So, on the surface, you could have a species that sprinted to all the features required for civilization - and then destroyed itself in a blaze of less-than-glory as we seem on a trajectory to do.
Edit: Note, I should add that I'd actually doubt this scenario could happen only because the evolution of human seems part of the general acceleration of evolution that can be seen throughout geological history.
There is discussion in the article about cephalopod communication, and how they use complex patterning and physical movement to communicate with each other. Is their level of communication and their information transfer speed as high as language? I don't think we can know very well without asking a cephalopod.
Now, that whole section is talking about modern cuttlefish, so I would agree with you regarding the author's hypothetical nautilus civilization.
The cephalopods we observe today would be many millions of years removed from the Silurian cephalopods. It would be like trying to gauge the language capabilities of humans from observing squirrels.
Memorized inherited tacit knowledge around campfires may had been our own specie's cultural medium, but other ways (with slower bitrate) can easily be entertained.
Vocalizations and their evolution were banned from discussion in the Royal Society because they did not leave a fossil record, so even meta-science was harder back then.
Would you count group hunting as “highly complex social behavior”? It’s not just a numbers thing, they communicate and coordinate with the group.
https://www.npr.org/2024/09/23/nx-s1-5120912/octopuses-and-f...
Octopuses also build colonies, using coconut shells and other tools.
https://www.newscientist.com/article/dn18281-octopuses-use-c...
https://www.science.org/content/article/scientists-discover-...
https://mashable.com/article/octopus-garden-colony-deep-sea-...
They can also solve human made puzzles.
https://journals.plos.org/plosone/article?id=10.1371/journal...
As for knowledge transfer, we know that they can teach other how to perform certain tasks. But beyond that, there seems to be a lack of research. Do they have complex language and can they transfer abstract “ideas”? My guess would be yes, but they communicate through color changes in ways that we have a hard time understanding. It seems likely that birds and whales have complex language, but we haven’t cracked the code on that even though their communication is much more like ours. Hopefully we find out some day.
https://www.scientificamerican.com/article/the-mind-of-an-oc...
https://www.forkingpaths.co/p/the-evolution-of-stupidity-and...
I often think that a more interesting question would be that if there were another civilisation here on earth right now, would we even recognise it as such?
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.
Check out the book "Mountain in the Sea", it's based on that premise and is a nebula award winner
> We are terribly preoccupied with tool use and physical artefacts as a defining factor of intelligence
In the context of civilisation, intelligence isn’t enough. Nomadic tribes are sapient, intelligent and have rich cultures, but they aren’t strictly civilisations.
The urban distinction is important because of economies of scale: pastoral societies are energy constrained. That doesn’t make them less interesting, again strictly speaking, personally it sort of does, but it does make them less powerful.
Within the Silurian context, the urban distinction is almost demanding: if humans stopped at Neolithic pastoralism, there is a good chance all evidence of our tool use would have disappeared within a few millennia, let alone millions of years.
tool use and physical artefacts
Maybe but it's also because these things are evidence of cultural transmission - a thing for which there hasn't been strong evidence of in other species and people do look for it in other ways.
When talking about aliens people often use the word "civilisation" to mean just "intelligence" and perhaps that's what you're doing because you're thinking about something that doesn't resemble a human civilisation. I agree with you that an alien intelligence might be very different from a human civilisation. Also, an alien intelligence might not even qualify as a form of life (it might be an artificial intelligence).
There probably is depending on your definition of a civilization. I’d imagine it looks something like an https://en.m.wikipedia.org/wiki/Ant_supercolony
our senses are only equipped to experience small subsets of the whole - there's a huge range of sounds impercetible to human ears, our eyes can only perceive light in the visible spectrum, a dog's nose can detect orders of magnitude more information than a human's.
if the five senses can only percieve a fraction of that which they have been honed for over millennia, it's not unreasonable to wonder if there is much more to the world/earth than meets the eye, inaccessible and unintelligible to physical ape life or existing in ways we aren't equipped to percieve.
yeah, and as far as I'm aware there isn't even a definition of "civilization" or "intelligence" that doesn't boil down to "sufficiently like me".
Trust me, if there were another civilization anywhere near us, we'd be at war with it.
No matter what the other civilization looks like, that's how we've always reacted. It's almost a defining characteristic of our civilization.
Interesting hypothetical, though I would put my money on birds rather than cephalopods :)
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.
The Silurian Hypothesis: Would it be possible to detect an industrial civilization in the geological record? (2019) https://arxiv.org/pdf/1804.03748
Primates first appeared around 65 million years ago.
The earliest dinosaurs arose over 200 million years ago.
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.
This extremely likely scientific theory is explored in Hibbett, MJ's "Dinosaur Planet"
http://www.mjhibbett.co.uk/dinosaurplanet/nindex.php
This is also pretty heavily explored in Voyager's Distant Origin episode.
https://en.wikipedia.org/wiki/Distant_Origin
And in Leonard Richardson's somewhat silly "Let Us Now Praise Awesome Dinosaurs" http://strangehorizons.com/fiction/let-us-now-praise-awesome...
And in Cixin Liu’s short story "Devourer" they even come back to earth for a last visit...
Of course, this has a back-story/history, see "Of Ants and Dinosaurs".
As a wise man once said, "Extraordinary claims require extraordinary evidence"...
> extremely likely
I think you misspelled "unlikely"...?
> The proposition that this was the case, is what I consider the actual most interesting hypothesis most likely to be false
>Probably the esteemed reader has noticed by now that I am no true believer in the Silurian hypothesis, but I like to entertain it
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.
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.
> It feels like an indictment of the pop-materialist world view, mass media control structures or just our current era of Internet.
Or maybe a triumph thereof? If people now care about what's true and dislike spreading interesting falsehoods, isn't that a good thing?
> Unfortunately, the era of "fact-check" and truthiness has spawned a class of professional debunkers.
This is a reaction to the “alternative facts” and the waves of general bullshit.
> At one point there were those who engaged in debates over flat-earth for the sake of honing rhetorical skills.
It’s one thing to engage in debates with your mates; it’s another to be subjected to a constant barrage of misinformation. Also, a couple of my mates from the “just asking rhetorical questions” period went full conspiracy theorists after a decade or so. I am less and less inclined to think that they were playing the devil’s advocates even back then.
> Flat-earth is typically used as a pejorative at HN.
Well, yeah. It’s the dumbest, most falsifiable of the stupid conspiracy theories, mixed in with a solid dose of religious fundamentalist. It’s not just games, at least not for everyone. Far too many people take it seriously, so it is unreasonable to act like it’s all fun and games.
Conspiracy theory is a self-reinforcing loop and people primed for this sort of thing do jump onto the next one without much critical thinking.
> We haven't entirely lost the ability to have stimulating conversations about Silurians, Atlanteans or other improbable fantasy scenarios, but the trend is approaching.
Fantasy is fantasy. This is not it. If you want to write a book about whatever thing you can think of, then have at it. The problem is when a fairy tale about aliens becomes gospel. So, if you don’t want to be debunked, don’t present fantasies as established facts.
> Today adults crusade against these absurdities without the slightest inkling of self-irony.
> Perhaps other posters can point to the underlying causes.
It's because a lot of the flat-earthers out there on the internet actually believe it. It's no longer an amusing discourse, fun little game or intellectual pursuit for the high-minded playful contrarian, it has transitioned to an actual conspiracy theory with actual adherents.
> Flat-earth is typically used as a pejorative at HN.
As it should be, given the above. It has become part of the wider conspiracy-sphere alongside chemtrails, 9/11 'truth' and all the other crap. It's no longer a sign of high intelligence or curiosity when someone brings it up, if it ever was.
Compare "BirdsArentReal", though honestly I expect that eventually to go the same way.
> At one point there were those who engaged in debates over flat-earth for the sake of honing rhetorical skills.
Do you have any proof that modern flat earthers were ever anything but a silly conspiracy group? The history I know of is of bizarre little flat earth cult groups denying basic science like this, and people outside their bubbles being amazed that they are not being sarcastic when encountering them in the wild.
Denying basic knowledge known since the ancient greeks or earlier is absurd to engage with.
[dead]
> Atlanteans
> Improbable fantasy
You mean as improbable and fantastical as the ancient Troy?
Oh right it turned out to actually exist, after much ridicule of its idea!
If anything, this kind of closed-mindedness is part of the problem.
Dismissing the abundant evidence for Atlantis is hindering our progress of finding it at best.
> experimental chemistry and physics would be harder to pull off underwater
Amphibious octopuses?[1] In the widespread and connected shallow seas of a supercontinent world?
[1] BBC Earth https://www.youtube.com/watch?v=ebeNeQFUMa0
And now I'm just sitting here imagining tentacles rising up from a puddle, holding a tightly wrapped fish-skin container, to do an experiment in the air.
Maybe they'd think of "going into the air" like early human chemists think of donning protective aprons. Air keeps the chemicals from getting on your skin.
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.
Actually it's the shoe layer.
Relevant PBS Space time video. https://www.youtube.com/watch?v=vyEWLhOfLgQ
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.
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.
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.
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.
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.
Cephalopods, of course, would have no opportunity to master fire.
It's not any particular technical development that separates humans from other animals, but the human relationship to technology as such. Humans only live by way of inserting external objects between themselves and nature, and they do this in an open-ended way. One could also talk about human self-domestication, and agriculture as a self-expanding ecosystem... Fire doesn't really capture the way humans actively modify their own conditions of life.
Why fire? Why is that so different from other tools that require significant effort to create?
Some animals use some tools, but mostly just sticks IIRC, with no effort to creating them, beyond breaking one off a tree. Maybe the criterion 'spend a lot of effort to create a tool' is the criterion, since having the time to spend on tool making requires someone else to get food for you etc. so is that getting towards a civilization?
>In particular, I believe the domestication of fire is the dividing line between humans and animals.
Must there be only 1 line? To me, language is another important one as it greatly increases the efficiency that one can communicate information generation to generation and it seems to have an impact on how we think. Children raised without exposure to language seem to suffer developmental issues, though this isn't well studied given the ethical issues involved in such a study.
As to how much communication is needed to count as a language, that is much harder to draw a definite line given that other species do communicate, but we don't consider them to have a language.
We don't even know when humans domesticated fire, though it certainly long predates the rise of civilization by any reasonable definition.
Certainly fire was a killer app for early hominids, but it doesn't mean it is a necessary step, nonetheless the necessary step on the road to intelligence.
I wonder for how long the satellites in the Earth's orbit would stay in orbit and be detectable as artificial entities.
The LAGEOS satellites, which are in an extremely stable orbit and made from dense materials that should maximize their stability, are expected to re-enter Earth's atmosphere in 8.4 million years.
The ones in high orbits would probably remain a very long time.
I wonder if NORAD would have detected it if a satellite remained from the previous civilization.
I think the main indicator of intelligent civilization would be burial sites and memorial monuments.
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.
That was actually put to the test, by really thinking hard about it, around 2018, or so. By serious scientists, not van Däniken types, or similar.
The conclusion was that we couldn't tell, between slowly milled between mile-high ice-shields and fluctuations of seawater-level alone.
Maybe, just maybe there would be the chance of some monument surviving buried in the center of a 'kraton', but why?
Do we build monuments there, now?
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)?
Let's do the math.
An adult human at rest breathes about 500mL air per breath, at about 12 breaths per minute. The inhaled air is about 21% O2, and the exhaled air is about 16% O2.
The density of air is 1.225 kg/m3, which is 1.225 g/liter. So 5% of a half-liter breath is, ballpark, 0.03 grams oxygen per breath, which at one breath per five seconds is 0.006 grams oxygen per second.
Dissolved oxygen in ocean water is about 0.008 g/liter. Fish are very efficient at extracting this, up to 80%. Squids and octopi are much less efficient, with octopi hanging out more in the 40% range, and squids much lower.
So this means that for every liter of water processed, an example octopus receives 0.003 grams oxygen, and if such an octopus were able to process two liters of water per second across their gills, they would receive as much O2 as a human.
This is not such an incredibly high number that it rules out cephalopod intelligence, especially when considering size differences.
Not a mention of Octopolis or Octlantis. Settlements of gloomy octopuses in Jervis Bay, Australia.
to save any interested parties a search: groups of 10-15 octopi have been dubbed 'octlantis' and 'octopolis' after being discovered off the coast of Australia. this is remarkable because octopi (including gloomy octopi) were previously thought to be largely solitary creatures which only interact when mating. octlantis features social hierarchies, disputes, and dens fashioned out of the shells of their prey which the creatures have been recorded evicting each other from. interesting stuff
https://www.smithsonianmag.com/smart-news/octopus-city-obser...
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?
I haven't read the paper either but billions upon billions of organisms constantly have some tiny chance of ending up in the conditions where they fossilize and could later be found. A few thousand or million exposed structures over the few-thousand-year lifetime of a civilization is, in comparison, a microscopically smaller chance of preservation. Nature, in contrast, gets effectively infinite shots at this, the fossils record still has gaps that dwarf the lifespan of human civilization as it is.
> 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?
Broadly speaking, fossils are rare and we site our cities on river deltas and such which have bad conditions for them.
Perhaps it's down to scale? If a single relief of a single building block survives, is that still considered a ruin of a football stadium, or just an imprint of a building block? The Colosseum would certainly not be able to survive for 100 million years. If some intelligent beings find a single building block while doing archaeology, they'll likely not be able to recognize it's purpose, if they even recognize the building block for what it is.
The structural integrity of (comparatively) smaller fossils is much more likely to survive for 100s of millions of years. A large building will be eroded by roots, wind, acid rain, etc. A fist sized rock containing the imprint of a trilobite, buried in soil and safe from most elements, will easily survive for 100s of millions of years.
Or perhaps the author meant that the vast majority of our buildings are not built to last. An asphalt highway - if unmaintained - will be unrecognizable in a hundred years. Roman roads survived for a few 1000 years because of their very crude nature: they are just a pile of rocks. But even such structures will fall prey to soil erosion and the relentless assault of nature. Unless said roads see foot traffic, they'd be also quickly overrun by trees and grasses.
It's a numbers game. The stadiums, highways, etc. are very few and are being built during a blink of history, compared to fossils which typically come from animals that were around for tens or even hundreds of millions of years. The sheer number of creatures that lived and died means we've had a few lucky pieces preserved.
Earth's surface isn't very static. On a geological timescale it is constantly moving and churning.
The fossil record is incredibly fragmented and incomplete.
There are weird structures that we discovered and haven't yet made sense of as well.
The known unknowns in science vast outnumber the known knowns.
>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.
I find this so sad, there is less and less place for humor in society to not offend anyone
We are in a golden age of comedy. There is literally more comedy in wider and deeper streams available for your consumption than ever before.
I just want to show my support for this statement by a fellow monkey
Just leaving this here in case anyone does a search for the name: Graham Hancock.
I prefer Randall W. Carlson.
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I'm waiting for it to become octopies.
octopodes
There’s an octoplethora of octoplurals!
And none of them more correct than the others.
> 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.
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.