14 ms·
The Silurian Hypothesis
- pvg 2y agoRelated discussion about a year ago https://news.ycombinator.com/item?id=38668884 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=34755970 https://news.ycombinator.com/item?id=23654393 https://news.ycombinator.com/item?id=23654393 https://news.ycombinator.com/item?id=21840320 https://news.ycombinator.com/item?id=21840320 https://news.ycombinator.com/item?id=17899478 https://news.ycombinator.com/item?id=17899478
- deleted 2y ago[deleted]
- dang 2y agoThanks! Macroexpanded: Possible to detect an industrial civilization in geological record? (2018) - https://news.ycombinator.com/item?id=38668884 https://news.ycombinator.com/item?id=38668884 - Dec 2023 (187 comments) Silurian Hypothesis - https://news.ycombinator.com/item?id=34755970 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 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 https://news.ycombinator.com/item?id=23654393 - June 2020 (138 comments) The Silurian Hypothesis - https://news.ycombinator.com/item?id=21840320 https://news.ycombinator.com/item?id=21840320 - Dec 2019 (52 comments) Silurian hypothesis - https://news.ycombinator.com/item?id=17899478 https://news.ycombinator.com/item?id=17899478 - Sept 2018 (7 comments)
- madaxe_again 2y agoI 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.
- malfist 2y agoCheck out the book "Mountain in the Sea", it's based on that premise and is a nebula award winner
- world2vec 2y agoIt's an amazing book, highly recommend.
- madaxe_again 2y agoSounds very much like my cup of tea, thanks! I’ve ordered it.
- necroforest 2y agoyeah, 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".
- empath75 2y agoI'm with you on intelligence, but the hallmark of civilization is right in the etymology -- the existence of cities.
- AnimalMuppet 2y agoWell, all right, do ants form cities? Yes, they do, at least of a kind. You could even argue that lichen is a city, inhabited by multiple species. I mean, I'm not sure I'd go so far as to argue than either of those really are a civilization. But if "city" is your sole criterion...
- PaulHoule 2y agoOr a beehive. Bees moved into the basement window of my house and watching them go in and out it seemed to me that this single beehive had more departures and arrivals than all the commercial airports in the world put together. If you look at the problem of "bee decline" from the viewpoint of the beekeeper where you are responsible for it you are responsible for a "city" of 50,000 insects that faces all kinds of threats from the inside and outside.
- ProjectArcturis 2y agoThe 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.
- deleted 2y ago[deleted]
- ragebol 2y agoWhy 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?
- tantalor 2y agoFire = automation
- AnimalMuppet 2y agoWhy fire? Because, as the GP said, it lets you use energy that isn't your own physical, biological energy. It lets you "level up" in a way that a muscle-powered tool doesn't. What they didn't say: It also lets you smelt metals. That lets you build much better tools.
- anentropic 2y agohaven'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?
- JumpCrisscross 2y ago> 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.
- flir 2y agoWait, wait, I thought mud was great for preserving fossils? Eg that Albertan Nodosaur fossil that turned up recently. And if they're working stone, the evidence won't even need a preservation step, because it was never organic - just a mudslide or a storm.
- Jerrrrrrry 2y ago0.00000001% of animals are fossilized. 99.9999% of animals are extinct. We had almost nothing, but a lot of it was inferrable.
- flir 2y agoI feel like everyone's jumping over the worked stone. We're assuming a technological civilization here, but without accidental geoengineering or even surviving artifacts. Flaked flint and pottery get everywhere. It just doesn't seem likely to me. The arguments seem very "God of the gaps" in nature.
- Jerrrrrrry 2y ago>The arguments seem very "God of the gaps" in nature. It is an argument from ignorance, but the timescales of pottery (1-20k ya) dwarf the porcelain thrones and nitrous oxide disposables that will be the only remaining artifact of our existence in 10 million years. Which is still a brief moment in time, compared to the timescales of the epoch proceeding.
- dghf 2y ago[flagged]
- henjodottech 2y agoNot a mention of Octopolis or Octlantis. Settlements of gloomy octopuses in Jervis Bay, Australia.
- Liquix 2y agoto 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-observed-180964936/ https://www.smithsonianmag.com/smart-news/octopus-city-obser...
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- edent 2y agoPrimates 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 http://www.mjhibbett.co.uk/dinosaurplanet/nindex.php
- ajdude 2y agoThis is also pretty heavily explored in Voyager's Distant Origin episode. https://en.wikipedia.org/wiki/Distant_Origin https://en.wikipedia.org/wiki/Distant_Origin
- arethuza 2y agoAs a wise man once said, "Extraordinary claims require extraordinary evidence"...
- edent 2y agoI think this is all the evidence you will need https://mjhibbett.bandcamp.com/track/the-theory-of-a-dinosaur-planet https://mjhibbett.bandcamp.com/track/the-theory-of-a-dinosau... The Cretaceous-Tertiary Extinction event occurred, as far as we know, Sixty five point five million years ago But even the interval of error in that estimated date Is longer than it took us humans to evolve from apes And if in that time we mammals managed to conquer space I believe the Dinosaurs could have done the same
- shiroiushi 2y agoPerhaps, but one big problem is the rocket equation: dinosaurs are generally very large compared to humans, so they'd need huge spaceships to carry them, and as we know, the rocket equation means you need far more fuel to lift an amount of mass to orbit. Perhaps only some smaller species of dinosaur evolved into an intelligent civilization.
- bumby 2y agoThe 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.
- Jerrrrrrry 2y agoMemorized 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.
- inkcapmushroom 2y agoThere 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.
- NoMoreNicksLeft 2y ago> s their level of communication and their information transfer speed as high as language? First, spoken language isn't extraordinarily fast. Most of us here have experienced points in our lives where speech has seemed laboriously slow. Second, we have through much of recorded history, relied upon correspondence and the written word, where communicating a few sentences worth of ideas took weeks. It is not outlandish to think that complicated, colorful shapes on the cuttlefish's back (pictures in the link, if you need a reminder) could convey an entire sentence' worth of information. With a refresh rate of what, 5 seconds? More than enough for human-speech-level speed. Whatever other challenges they face, communication just isn't one of those.
- andrewflnr 2y agoBefore 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.
- jjk166 2y agoThe presence of fast predators on land certainly didn't prevent us from evolving.
- yencabulator 2y agoIt 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.
- openrisk 2y ago> 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...
- sdenton4 2y agoOf course, we do have tree hugging octopus today: Save the Pacific Northwest Tree Octopus! https://zapatopi.net/treeoctopus/ https://zapatopi.net/treeoctopus/ (j/k)
- alexey-salmin 2y ago> 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.
- nickpinkston 2y agoSouth Park subtitle: "This is what de-growthers actually believe."
- crystal_revenge 2y agoThat'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.
- dvh 2y agoIf 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)?
- margalabargala 2y agoLet'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.
- regnull 2y agoI wonder for how long the satellites in the Earth's orbit would stay in orbit and be detectable as artificial entities.
- hollerith 2y agoThe 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.
- askvictor 2y agoLike, "in the order of a billion years" very long time?
- hollerith 2y agoI don't know.
- margalabargala 2y agoProbably not. The moon was formed in a massive impact 4.5 billion years ago which for a time, gave the Earth a ring. There would have been large, human-satellite-sized rocks at every orbital altitude. None of these remain. We would expect the number remaining in orbit to decrease asymptotically over time, so if it has decreased to zero (or one, technically) then clearly satellites cannot remain in Earth orbit for many billions of years.
- mr_toad 2y agoEven the orbit of the Moon has shifted significantly over billions of years. Aside from orbital changes, things in space erode. A combination of meteoroid impacts, radiation, solar wind, and ablation will eventually obliterate most artefacts in space.
- aa-jv 2y ago>I wonder if NORAD would have detected it if a satellite remained from the previous civilization. We might've come pretty close: https://en.wikipedia.org/wiki/Black_Knight_satellite_conspiracy_theory https://en.wikipedia.org/wiki/Black_Knight_satellite_conspir...
- somethingsome 2y ago>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
- monkeydreams 2y agoWe are in a golden age of comedy. There is literally more comedy in wider and deeper streams available for your consumption than ever before.
- monkeycantype 2y agoI just want to show my support for this statement by a fellow monkey
- stonethrowaway 2y agoJust leaving this here in case anyone does a search for the name: Graham Hancock.
- LargoLasskhyfv 2y agoI prefer Randall W. Carlson.
- dhosek 2y agoIt’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.
- dboreham 2y agoActually it's the shoe layer.
- perihelions 2y agoEvidence for the cephalopod hypothesis. Sentient octopusers would have had gone through large numbers of shoes
- bregma 2y agoOr gloves. Depends on how you look at it.
- kombookcha 2y agoIf an ancient octopus wanted to wear some rubber-like workwear to do his dirty civilization-building, would he wear a big glove with 8 'fingers', or would he wear a flexible thimble on each tentacle?
- dhosek 2y agoI think it would be individual sucker covers.
- kombookcha 2y agoGod what a pain in the ass to put them all on and take them all off, no wonder they didn't make it
- lproven 2y ago
- mncharity 2y agoThe Silurian Hypothesis: Would it be possible to detect an industrial civilization in the geological record? (2019) https://arxiv.org/pdf/1804.03748 https://arxiv.org/pdf/1804.03748
- crystal_revenge 2y agoSurprised 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_Thermal_Maximum https://en.wikipedia.org/wiki/Paleocene%E2%80%93Eocene_Therm...
- l3x4ur1n 2y agoSend it to space. To multiple places. Next guys should be able to find it sooner or later.
- minorhassle 2y agoIf only there was some way to mark a planet with a special marker.. that could be seen from anywhere in the solar system from any angle. Maybe some rings?
- tzs 2y agoSome 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.
- mncharity 2y ago> 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 https://www.youtube.com/watch?v=ebeNeQFUMa0
- yencabulator 2y agoAnd 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.
- deleted 2y ago[deleted]
- transfire 2y agoI 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.
- LargoLasskhyfv 2y agoThat 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?
- cubefox 2y ago> 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.
- jjk166 2y ago> If modern housing can't survive geological time, then dinosaur fossils also can't survive it. That assumption does not hold.
- cubefox 2y agoA lot of houses use hard stone in various places, sometimes even granite, which is a lot more durable than any fossilized skeleton. So the assumption definitely holds.
- jjk166 2y agoAnd those stones will survive, but the structure they are a part of will not. When you pull a stone out of a structure, it becomes just a stone. Structures become unrecognizable in a relatively short time span. Fossils are as durable as stone (indeed they are stone) but their structure is preserved in such a way that they remain distinctly identifiable for millions of years.
- cubefox 2y ago> When you pull a stone out of a structure, it becomes just a stone. With a specific shape (e.g. square) that could only have been produced by the Silurians, not by natural processes.
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- palmfacehn 2y ago> 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.
- Nursie 2y ago> 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.
- varelse 2y ago[dead]
- jdthedisciple 2y ago> 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.
- Anotheroneagain 2y agoSometimes 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.
- xg15 2y ago> 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-event-how-cyanobacteria-change https://asm.org/articles/2022/february/the-great-oxidation-e...
- renewiltord 2y agoAnother 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.
- throwawayffffas 2y agoRelevant PBS Space time video. https://www.youtube.com/watch?v=vyEWLhOfLgQ 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.
- mppm 2y agoInteresting 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.