openrisk 3 days ago | next |

> 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...

alexey-salmin 3 days ago | root | parent | next |

> 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.

TeMPOraL 3 days ago | root | parent | next |

> 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

shiroiushi 3 days ago | root | parent |

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?

lproven 2 days ago | root | parent | next |

> 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.

Terr_ 2 days ago | root | parent | prev | next |

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.

coremoff 2 days ago | root | parent | prev | next |

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.

shiroiushi 3 days ago | root | parent | prev | next |

>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.

digging 3 days ago | root | parent | prev | next |

A strategy for avoiding one particular death is not a strategy to ensure survival.

There are >1 ways for a civilization to become extinct.

openrisk 2 days ago | root | parent | prev | next |

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.

FrustratedMonky 2 days ago | root | parent | prev | next |

"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'.

nickpinkston 3 days ago | root | parent | prev |

South Park subtitle:

"This is what de-growthers actually believe."

crystal_revenge 3 days ago | root | parent |

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.

nickpinkston 2 days ago | root | parent |

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.

jjk166 2 days ago | root | parent |

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.

nickpinkston 2 days ago | root | parent |

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.

wruza 3 days ago | root | parent | prev | next |

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.

yencabulator 2 days ago | root | parent | next |

Well, the carbon our civilization has been burning started forming about 350-300 million years ago (from Carboniferous period, it's in the name), and the Silurian period was 420-440 million years ago, so what Silurians would have had under their tentacles isn't what we bootstrapped our society with.

Maybe they used plenty of the under-your-tentacles fuel sources, but it's been a very long time since, and it's hard to tell.

https://en.wikipedia.org/wiki/Geologic_time_scale

echelon 2 days ago | root | parent | prev | next |

I'm not a fan of the Silurian hypothesis, but maybe it could have predated Theia?

More tantalizing, maybe there's a universe-level Silurian analog where our Big Bang was predated by another universe teeming with intelligent life.

Maybe we get Silurian'd ourselves.

jjk166 2 days ago | root | parent |

Theia hit Earth within 100-150 million years of the formation of Earth. It seems exceedingly implausible that life could not only emerge but go through all the stages of development necessary to achieve advanced intelligence in such a short time compared to what it took the "second" time around.

wruza 2 days ago | root | parent |

And in that period it wasn’t particularly habitable either. An observer may not find that big of a difference between a recently formed planet and a planet recently hit by another planet.

ComplexSystems 2 days ago | root | parent | prev | next |

One answer is that this "initial phase" may have lasted a total of a few hundred years, which is a tiny blip on geological scales. Even with humans, it looks like it's going that way.

colordrops 3 days ago | root | parent | prev | next |

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.

Byamarro 3 days ago | root | parent | prev |

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.

xg15 2 days ago | prev | next |

> 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...

renewiltord 2 days ago | root | parent |

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.

crystal_revenge 3 days ago | prev | next |

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...

tzs 3 days ago | root | parent | next |

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.

profsummergig 2 days ago | root | parent | prev | next |

> 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

Terr_ 2 days ago | root | parent | next |

They might have just been much better than dinosaurs at not drowning in bogs and other rare fossil-promoting circumstances.

saberdancer 2 days ago | root | parent |

And number of dinosaurs found compared to number of individual dinosaurs that ever lived is staggeringly low.

shmeeed 2 days ago | root | parent | prev | next |

Not a biologist, but OTOH they might have had a very different body structure that doesn't conserve well, e.g. like molluscs.

Or maybe we _did__ find their remains and just have no idea they were part of an intelligent civilization. I mean, that's not a question any respectable researcher would be inclined to raise in the paper about the discovery...

urspx a day ago | root | parent | prev |

I think the point is that the 'people'/their remains might be findable, but trace or proof of their civilization would not?

kevinkeller 3 days ago | root | parent | prev | next |

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.

kergonath 2 days ago | root | parent | next |

> If PETM was due to large scale use of hydrocarbons, there should be evidence of depletion in the strata, right?

And all the byproducts of this use. We are leaving abundant traces of our existence basically everywhere. We can see it in the ground, in the seas, in the ice caps. Our existence will be very obvious to anything caring to just dig for quite a long time.

Terr_ 2 days ago | root | parent | next |

Just because traces are widespread doesn't mean they'll last for 60 million years.

For example, we don't have any ice core data older than ~5 million years. (Much lower, if you limit it to continuous spans.)

kergonath a day ago | root | parent |

The content of the atmosphere gets washed out by rainfall and does end up in the sedimentary record. Similarly, we can follow the oceans’ acidity from sediments. Large chemical changes would also show up in isotope ratios.

jjk166 2 days ago | root | parent | prev | next |

The ice caps are only about 30 million years old, and the land and oceans are similarly transformed over long time scales. The only techno signature I'm aware of that would be clearly detectable 50 million years after our civilization is gone is reinforced concrete, which should produce a worldwide layer of a limestone-like mineral with iron inclusions that would be both unique in the geologic record and difficult to explain by any natural process. If a civilization did not use reinforced concrete nor some other such material that would leave a similar signature, it would be quite difficult to detect at that timescale.

lovecg 2 days ago | root | parent | prev |

We’re talking about 50 million years. Literal continents move in that amount of time.

kergonath a day ago | root | parent |

We get bones and feathers from animals living 10 million years before that. We can find the traces from the Chicxulub impact across the whole world. Same for large volcanic eruptions. Burning enough stuff to cause this kind of global warming would leave plenty of chemical traces. It’s just not serious.

jjk166 2 days ago | root | parent | prev |

I'm not sure if that's a safe assumption. Do we know what the sources we are exploiting right now are going to look like in tens of millions of years? Our models of the evolution of hydrocarbon reserves are based on those we've found, and we simply assume the differences between different deposits are natural in origin. It's easily possible that places where we didn't find hydrocarbons did in fact have them at a previous point in time, or that there was more in a given reserve in the past.

FrustratedMonky 2 days ago | root | parent | prev | next |

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?

baq 2 days ago | root | parent | prev | next |

> 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.

l3x4ur1n 3 days ago | root | parent | prev | next |

Send it to space. To multiple places. Next guys should be able to find it sooner or later.

minorhassle 3 days ago | root | parent |

If 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?

UncleOxidant 3 days ago | root | parent | prev | next |

> a civilization like this would not leave a trace on the geological record.

At all? Like nothing that would be observable 50M years later?

brabel 2 days ago | root | parent |

Nothing built with "usual" materials we have, mostly because of the constant movements and subduction of tectonic plates, as well as volcanism and erosion.

Think about something you believe would last 50 million years. I am sure someone will be able to point out how and why that would just disappear after such ridiculous amount of time.

red_admiral 2 days ago | root | parent |

Aren't the oldest fossils we know of assumed to be something like 500 million years old?

Or you could try leaving particular "signatures" of radioactive elements. Not ones with a short half-life, obviously, but xenon-124 lasts pretty long, tellurium-128 will survive anything except the heat death of the universe, and there's a few others like that.

yencabulator 2 days ago | root | parent |

Sure, how many >300 million year old fossils have we found related to how many animals lived at that time, over that span of time? The problem is many methods might work -- literally you accidentally falling on a trip to Florida might work -- but the probability can be very low.

red_admiral 2 days ago | root | parent | prev |

Put up a plaque reading "This is not a place of honor ..." ?

pvg 3 days ago | prev | next |

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

dang 3 days ago | root | parent | next |

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)

andrewflnr 3 days ago | prev | next |

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.

yencabulator 2 days ago | root | parent | next |

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.

bumby 3 days ago | prev | next |

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.

chubot 3 days ago | root | parent | next |

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

stevenwoo 3 days ago | root | parent | next |

Not only short lifespan (some live four years), but all species die after laying eggs or after the eggs hatch so there can only be genetic transfer of information like the social insects, ants and termites. There would need to be some evolutionary leap to have them survive longer than required now or extraordinary genetic engineering ala Children of Time.

andrewflnr 3 days ago | root | parent |

Not necessarily. You could, in principle, have the information transfer happen via octopuses in their community that aren't laying eggs yet.

stevenwoo 3 days ago | root | parent |

That could be true. But all of the ones I've seen in nature documentaries lay their eggs at approximately the same time which probably were the most interesting to document for laypeople not representative of all these. The four years number popped in my head from this one example, where she tended her eggs for four years but lives about seven years total. Given the length of brooding I would assume these do NOT lay their eggs at the same time like some sort of cicada multiple years cycle. The counter argument is these are solitary animals, so we would need to find a social version of these that do not lay their eggs at the same time, I'd like to see that in the next nature documentary!

https://www.mbari.org/news/deep-sea-octopus-broods-eggs-for-...

yencabulator 2 days ago | root | parent | next |

Even if there was an "egg-laying season", there could be a generation in-between that is not yet ready to lay eggs, that then teaches the newborns. Staggered lives, minimal overlap with direct parent, but still passing cultural heritage as a village.

andrewflnr 3 days ago | root | parent | prev |

Yeah, evolving social behavior is a prereq. We're doing speculative biology, not real biology. :) The idea might be, if they lay eggs at 3 years old, then the 2 year olds do the teaching. But by the time they can do that, I bet it's not that hard to lose the brood-until-you-die behavior either.

Terr_ 2 days ago | root | parent | prev | next |

> Humans do seem to have some the longest life spans on the planet, and that's an important adaptation

Most of that is just using medicine and tools, as opposed to any purely biological longevity factor.

chubot 2 days ago | root | parent |

Medicine increased the average life span, but I don't think it increased the maximum very much

A lot of figures you see are biased by infant mortality and such

Random article I googled - Did Ancient People Die Young?

https://www.sapiens.org/biology/human-lifespan-history/

The outliers are the ones who drive history - I am imagining an 80-year-old wise man or woman, 10,000 years ago, who changed history

We still don't know how language came about, and how writing came about, and I can imagine that a limited life span / reproductive goals would make those things less likely

yencabulator 2 days ago | root | parent |

The severity of wounds was very different even just a hundred years ago. It was dramatically different more than some 5000 years ago. These days mortality is heavily based on infant mortality, but 10,000 years back the statistics might be a bit different. I'm sure infant mortality was still a significant factor, but I'd also expect modern medicine elevated its significance a lot.

https://en.wikipedia.org/wiki/History_of_wound_care

chubot a day ago | root | parent |

Sure, but that changes the average too, not the maximum

When I say maximum, I mean that presumably 10,000 years ago, there were people who didn't get sick, didn't get wounded, etc. They died of "old age"

How long did they live?

There were far fewer of them, but they existed, and were probably productive, passed on knowledge, and moved civilization forward. They could have been leaders, or raised leaders, etc.

joe_the_user 3 days ago | root | parent | prev | next |

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.

shiroiushi 3 days ago | root | parent |

>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.

It is interesting how we evolved all these necessary things pretty quickly, though if we look at other apes, they generally also possess opposable thumbs and binocular vision. Sometimes I wonder if there was help, such as a large, black monolith...

inkcapmushroom 3 days ago | root | parent | prev | next |

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.

NoMoreNicksLeft 3 days ago | root | parent | next |

> 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.

bumby 3 days ago | root | parent | prev | next |

I guess the part that I could’ve been more explicit about is that I am thinking both complex language and complex language skills being necessary together to push civilization forward. The takeaway I had from the articles communication discussion was that their communication, while unique, is focused directly on mating, and predation (or avoiding predation). Those goals seem to be the norm in the animal kingdom. While I think the argument could be made that the human demonstrations can be to the same ends, they are many more layers of abstraction in between which is what ends up creating complex civilization.

(Eg, status is a form of mating, but we humans have so many tangential levels of displaying status that technology like a Lamborghini can become a mating signal, rather than using pure dominance. The combination of complex social behaviors and communication are necessary before the technology develops)

inkcapmushroom 3 days ago | root | parent |

I think we can very easily tell when they are communicating about mating or predation. We can read those signals in virtually any animal, there seem to be near-universal signals which we can easily talk about in research. Maybe when they are just having a chat, it might not look like anything to us, and we can only really tell what they're saying when they're "shouting".

Or maybe we are missing lots of nuanced details being conveyed in the message. We think the tiger stripe aggressive pattern just means "back off", but maybe he's really "reading off" a detailed list of his feats of bravery to intimidate his opponent or spitting the cephalopod equivalent of a diss track!

jjk166 2 days ago | root | parent | prev | next |

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.

Jerrrrrrry 3 days ago | root | parent | prev | next |

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.

sholladay 3 days ago | root | parent | prev |

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...

bumby 3 days ago | root | parent |

My guess is that abstract ideas is an outgrowth of language and also necessary for the development of the complex societies the article is positing. I would also be careful not to conflate complex language (for example, dialects in whales) with the development of complex abstract ideas (for example, mathematics). It seems to me the latter is necessary for the complexity discussed, but unclear if the extent to which it exists in other species. But I agree, hopefully we can learn more someday on the way they are both similar and dissimilar to human cognition.

(I should add that there are some like Stephen Meyer who think certain abstract cognition is more magical and unable to come from basic evolution, but this has a theistic bent)

dboreham 3 days ago | root | parent |

> but this has a theistic bent

Aka is obviously wrong.

bumby 3 days ago | root | parent |

I’m not inclined to believe his hypothesis, but counterclaim have not been proven true to my knowledge either. If we haven’t proven why humans are uniquely able to communicate complex ideas of past/future for example, I’m much more humble about claiming anything is obvious. The irony is that strong positions in the absence of evidence are making similar errors.

madaxe_again 3 days ago | prev | next |

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.

JumpCrisscross 3 days ago | root | parent | prev | next |

> 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.

pvg 3 days ago | root | parent |

Nomadic tribes are sapient, intelligent and have rich cultures, but they aren’t strictly civilisations.

Some pastoral societies have taken serious issue with this view

https://en.wikipedia.org/wiki/Mongol_Empire#/media/File:Mong...

JumpCrisscross 3 days ago | root | parent |

> Some pastoral societies have taken serious issue with this view

Where is the evidence the Mongols took issue with this view? They certainly seemed to recognise the value of cities.

To my knowledge, the practice of falsely conflating intelligence and civilisation to be offended that not every society formed a civilisation is a modern occupation.

pvg 3 days ago | root | parent |

Where is the evidence the Mongols took issue with this view?

I think if you eat all neighbouring civilizations in a few decades, you're definitely a civilization.

JumpCrisscross 3 days ago | root | parent | next |

> if you eat all neighbouring civilizations in a few decades, you're definitely a civilization

If you run the cities, yes. If you only raid them, no.

(The Mongols built roads and founded a Chinese dynasty. They were a civilisation.)

pvg 3 days ago | root | parent |

This is a slightly silly discussion because the 'civilization' the Silurian hypothesis is concerned with is something like human civilization as a whole.

Whether pastoralists are a 'civilization' (or even more fraught, 'civilized') seems like a completely arbitrary distinction to try to make, especially on the basis of something like 'cities'. The ability to organize, direct, coordinate, supply and project military power over great distances is a hallmark of plenty of things we think of as 'civilizations' and the Mongols were easily the world heavyweight champion of that, in their day. A great number of people found out the fact a stone wall is much harder to move than a yurt is not the tremendous civilizational advantage they thought it was.

JumpCrisscross 3 days ago | root | parent |

> is a slightly silly discussion because the 'civilization' the Silurian hypothesis is concerned with is something like human civilization as a whole

Going back to the top comment: “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.”

AlotOfReading 3 days ago | root | parent |

I've done archaeological work in Mongolia. The oldest things I've found predate the last glacial maximum. Those rocks might not have survived a few million more years, but I can certainly think of lithics that would.

pvg 3 days ago | root | parent | prev | next |

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.

bloak 3 days ago | root | parent | prev | next |

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).

Liquix 3 days ago | root | parent | prev | next |

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.

necroforest 3 days ago | root | parent | prev | next |

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".

empath75 3 days ago | root | parent |

I'm with you on intelligence, but the hallmark of civilization is right in the etymology -- the existence of cities.

krisoft 3 days ago | root | parent | next |

> hallmark of civilization is right in the etymology -- the existence of cities.

That is not really the etymology of "civilisation" though. City and civilisation share etymological roots, but city is not the etymological origin of the world civilisation.

And of course then we just ask the question: what are cities? Do gopher, or prairie dog colonies count? (or are those just towns? :)) How about ant colonies or bee hives?

Clearly all of the above share some similarities with some human settlements. They also have important differences of course. So if we want to decide if there are other "civilisations" on Earth parallel with us, we have to be more precise with our definitions.

JumpCrisscross 3 days ago | root | parent |

> city is not the etymological origin of the world civilisation

Civilisations are a subset of societies [1]. Urbanisation is commonly held as a divider between complex societies and full-blown civilisations.

> then we just ask the question: what are cities?

This is valid. I’d say the defining attribute is economies of scale. Ant colonies and bee hives demonstrate elements of this; the sum is greater than the whole.

Whether ants and bees form complex societies is less debatable, unless we reduce the terms to mean intricate where we begin enveloping colonies of trees and every social animal, potentially even just multicellular life, which while poetically pleasing isn’t useful.

[1] https://en.m.wikipedia.org/wiki/Civilization

AnimalMuppet 3 days ago | root | parent | prev |

Well, 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 3 days ago | root | parent |

Or 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.

kijin 3 days ago | root | parent | prev |

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.

mppm 21 hours ago | prev | next |

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.

edent 3 days ago | prev | next |

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

Borrible 3 days ago | root | parent | prev | next |

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".

arethuza 3 days ago | root | parent | prev | next |

As a wise man once said, "Extraordinary claims require extraordinary evidence"...

edent 3 days ago | root | parent |

I think this is all the evidence you will need 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 3 days ago | root | parent |

Perhaps, 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.

palmfacehn 2 days ago | prev | next |

> 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.

lmm 2 days ago | root | parent | next |

> 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?

palmfacehn a day ago | root | parent |

There are a few related responses in this thread.

>Or maybe a triumph thereof?

Losing the ability to describe the Silurian hypothesis or other improbable ideas without prescribing them as objective truths doesn't feel like a triumph. The inability to have a discussion without a pop-materialist crusader interjecting, "But it isn't real!!!" feels like a hindrance.

Flat Earth was just one example to illustrate the trend. Clearly it triggered posters to sneer at disfavored out-groups.

>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 we should accept this trend and appeal to the lowest common denominator, because some heretics might believe the wrong thing? If nothing else, we should appreciate that the religious types describe their world in terms of faith. There's no slight of hand in their presuppositions. They know when they are accepting presuppositions on faith. From my side, one of the biggest criticisms of some the fundamentalists would be their intolerance of differing world views. The above quote is no better in that regard.

>...don’t present fantasies as established facts.

Again, there's an important distinction between prescribing something as an objective truth and describing it for the sake of discussion. Losing the ability to do the latter because some are unable to appreciate the distinction lowers the bar. Forbidding an entire class of hypotheticals because the hoi polloi might not appreciate the distinction is an exercise in paternalism. Although the paternalism feels less than genuine in this case. Equally likely that tribalistic ulterior motives are at play.

Consider found-footage horror films or reality TV. Clearly there is a value in presenting the fictional as real. Would we demand disclaimers to protect the public? If that isn't absurd enough, consider that some regard explicitly fictional events and locations from Marvel films as real.

>Americans think Wakanda and Zamunda are real places

https://www.citizen.co.za/entertainment/celebrity-news/ameri...

If we follow this line of reasoning, even pop-culture hasn't lowered the bar enough for truthiness to prevail.

>> 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

Perhaps instead of lowering the bar to protect the public from what posters here describe as unacceptable beliefs, we should raise the bar. Perhaps we shouldn't be using pejoratives or sneering at others. Instead we should seek to have stimulating discussions, question our own preconceptions and recognize that HN exists within its own bubble. Otherwise, what is the point?

>And then surprised again how quickly they drop it if the belief becomes goes out of fashion and fails to signal in-group membership for whichever bubble

Nursie 9 hours ago | root | parent |

> Perhaps instead of lowering the bar to protect the public from what posters here describe as unacceptable beliefs, we should raise the bar.

Which bar is being lowered? What do you even mean by that?

> Perhaps we shouldn't be using pejoratives or sneering at others.

When they are pushing demonstrably stupid, scientifically illiterate ideas as factual, we absolutely should call this out.

> Instead we should seek to have stimulating discussions, question our own preconceptions

When someone brings up flat earth theories it is likely they are doing it because they're -

a) A true believer, deep in a hole of false belief, angry that the government is hiding the flat-earth truth from them b) Grifting those true believers

Such people aren't challenging preconceptions, they generally either don't understand what they're showing to others as evidence and don't understand what's wrong with it, or they're actively hostile to discussion because their identity is invested in conspiracy theories, or they're actively hostile because any debate threatens their income stream.

> recognize that HN exists within its own bubble. Otherwise, what is the point

I again don't understand what it is you want here? There are no two ways about it, we know that the earth is an oblate spheroid. Getting "outside the bubble" means what? Recognising that there are people who believe otherwise? There are, and they should be pitied. It's not a matter of point of view.

Nobody's stopping you having an amusing little conversation about how a flat earth might work, hell, some of the funniest fiction I know of is set on a Discworld and if you read "Strata" by the same author, you'll find some sci-fi thought experiments around it, and they're great. And nobody's stopping this guy talking about the Silurian hypothesis. In fact surely such things are even more fun if you look at the limitations and objections - how would a Silurian population fit into what we know about the geological record? Someone coming along and saying "Ah, but where's the change in mineral make-up for reason x, y and z, your civilisation would certianly leave that trace?" can add to that, because now you can go back to your hypothesis and account for it! All good fun. It's when you start pushing it as factual and something that did happen, that you'll get people fact-checking.

Honestly your post reads a little like trolling - you seem to be intentionally conflating the intellectual pursuit of stimulating, slightly fantastical discourse with the large population of people who irrationally cling to bullshit.

Look at a different topic for a minute - free energy. Lots of sci-fi exists in which it is posited. Lots of thought experiments exist about it, about the effects it might have on society etc. But when people try to say that they have found a way to do it, we should be sceptical until they show results. And then when they start to monetise this based of hype, should we not call this out? At that point we often see points such as yours raised - change your world view, you should be open to being challenged, isn't it possible you just don't understand the science? But all they really are is exhortations to blind faith, and cover for people who are actively exploiting that faith and the ignorance of others for their own gain.

kergonath 2 days ago | root | parent | prev | next |

> 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.

brabel 2 days ago | root | parent |

> 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.

Just the other day someone posted on a social network that they believe the war going on in Ukraine is "fake". I believe they used the word "Psyop". They claim they do not see any footage of the war, unlike the war in Israel, so it must be fake. So, I posted links to footage of several battles, which are very easy to find even on Youtube, and linked to one of the many "mappers" who post map update videos of the changes in the frontlines daily, which also always include plenty of footage of battles (usually with a couple of weeks delay given that videos from the battles that are still going on are highly sensitive as the military can use them in their favour). The person still denied that those things prove anything, and doubled down by saying the footage just proves their point that the war is not killing a million people (the one-million dead figure seems to be circulating in part of the media in the USA. I believe that's a high estimate , but still realistic when thousands of soldiers seem to be dying on both sides every day, and the war is approaching 3 years already).

It's incredible to me someone that seems like a real person who appears to participate in politics locally (looking at their profile, they are highly politically engaged in Texas with the Republican Party) could just dismiss obvious evidence like that just because it does not support some bizarre belief that they formed... but this seems to be really common these days!

photonthug 2 days ago | root | parent |

Sounds like someone who has got an angle and thinks they can profit from lies / misinformation, I seriously doubt anyone saying that stuff believes it.

On the bright side, Alex jones and infowars have been held accountable for spreading doubt about whether school shootings happened. Anyone who is denying the whole existence of obviously real large-scale conflicts can probably be held accountable in the same way if they are demonstrably profiting from the lies. If on the other hand it’s just signaling allegiance to an in group without merch and money changing hands.. maybe not.

Nursie 2 days ago | root | parent |

> I seriously doubt anyone saying that stuff believes it

I think you’d be surprised. And then surprised again how quickly they drop it if the belief becomes goes out of fashion and fails to signal in-group membership for whichever bubble they occupy.

Specific belief seems quite malleable when what’s important is social signalling.

Nursie 2 days ago | root | parent | prev | next |

> 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.

simiones 2 days ago | root | parent | prev | next |

> 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.

jdthedisciple 2 days ago | root | parent | prev |

> 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.

kergonath 2 days ago | root | parent |

> You mean as improbable and fantastical as the ancient Troy? > Oh right it turned out to actually exist, after much ridicule of its idea!

There is a missing step in your logic. Present facts and they will be believed. Much of the ancient history of the human species is in flux, and specific fields of archaeology get upended regularly.

I will believe in Atlantis, or Thule, or whatever, when there are proofs. In the meantime it’s a fantasy dreamt by ancient Greeks, opportunistically repurposed to justify behaviours ranging from the mundane to war crimes.

> If anything, this kind of closed-mindedness is part of the problem.

Come on. The fact that knowledge evolves does not mean that everything we believe is false right now will be proved at some point. Some things are just false.

photonthug 2 days ago | root | parent |

This comment rubs me the wrong way. The fundamental error for conspiracy-theory types is to confuse "unproven" as "probably true". It's basically the same error when naively wielding the scientific method so as to conflate "unproven" and "disproven".

> I will believe in Atlantis, or Thule, or whatever, when there are proofs. In the meantime it’s a fantasy dreamt by ancient Greeks, opportunistically repurposed

The appropriate attitude for scientists is agnosticism, but this hints that you already have your preferred answer. Skepticism should cut both ways.

Logically, if you'd have trouble proving the existence of our own contemporary cities after the passage of geological time, then you'd likely have trouble with any other cities. And for archaeology specifically, new discoveries happen all the time, more frequently than say fundamental physics, so more humility also seems appropriate. Atlantis in particular might be fraught with baggage, but as another example, scholars are still undecided about whether the hanging gardens of Babylon (one of the wonders of the ancient world) actually existed, where they were exactly, or if they were always legendary. Do you have a strong preference for that too, or does the change in context also change your process/preferences for establishing ontologic / epistemic status there?

> Come on. The fact that knowledge evolves does not mean that everything we believe is false right now will be proved at some point. Some things are just false.

Again, things are false that are proven false. Unproven things are just that, unproven, unless they are categorically impossible. Obligatory "I like science and am not a flat-earther" disclaimer, but science (or those claiming to speak for it) will have to occasionally accept well-intentioned criticism as well as dish it out. The best way to respond to a cult-like following of misinformation is not to build a cult-like following for science.

kergonath a day ago | root | parent |

> It's basically the same error when naively wielding the scientific method so as to conflate "unproven" and "disproven".

That is not what I wrote, at all.

> The appropriate attitude for scientists is agnosticism, but this hints that you already have your preferred answer. Skepticism should cut both ways.

Skepticism means not accepting an argument at face value without some kind of validation. Something that is partly supported by evidence can be used temporarily as the best current explanation and be discarded or improved in the face of new evidence.

What really rubs me the wrong way is people using skepticism as a weapon of disinformation and rhetorical argument. The first thing to be skeptical of is yourself, because 1) as an individual you are very likely to get carried away by ideology or emotion and 2) this is very difficult to correct because you’re using your own brain to assess and correct itself. If your pet theory is unsupported by evidence and you need a whole scaffold of conspiracy theories for it to make some kind of sense, then the first target of skepticism is yourself, not the others. And you really cannot blame other people to point that out.

> Logically, if you'd have trouble proving the existence of our own contemporary cities after the passage of geological time, then you'd likely have trouble with any other cities.

There is a logical misstep here. We have no trouble whatsoever proving that cities existed, even if we did not find every individual city. For the whole Atlantis thing to make sense, you’d need a whole species able to build cities and manipulate climate intentionally or not, and yet they never left any trace outside this specific location, and something cataclysmic that at the same time also left no trace. It’s not a problem of lack of people looking for it, either. I am really sorry if it annoys you but here it is: the whole thing is entirely unsupported. Show some evidence and this will change. Do your work: it’s not a religion and we are not supposed to accept unfounded beliefs.

> And for archaeology specifically, new discoveries happen all the time, more frequently than say fundamental physics, so more humility also seems appropriate.

You are making that mistake again, so let me reiterate: an evolving field of knowledge does not mean that an unproven theory has any weight and should be accepted uncritically just because someone might find it in the future. Though I do agree on humility, but humility is not only for others, just like skepticism.

mncharity 3 days ago | prev | next |

> 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

yencabulator 2 days ago | root | parent |

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.

dhosek 3 days ago | prev | next |

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.

dboreham 3 days ago | root | parent |

Actually it's the shoe layer.

perihelions 3 days ago | root | parent | next |

Evidence for the cephalopod hypothesis. Sentient octopusers would have had gone through large numbers of shoes

bregma 2 days ago | root | parent |

Or gloves. Depends on how you look at it.

kombookcha 2 days ago | root | parent |

If 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?

Anotheroneagain 2 days ago | prev | next |

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.

ProjectArcturis 3 days ago | prev | next |

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.

bokoharambe 3 days ago | root | parent | next |

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.

ragebol 3 days ago | root | parent | prev | next |

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?

nkrisc 3 days ago | root | parent | next |

Because with a small amount of your own energy as input, you unlock vast amounts of potential chemical energy. No other tool used by other animals comes anywhere close in terms of efficiency. And no other animal is anywhere near as "civilized" (loaded term, I know) as humans are.

It is clear there is something different between humans and all other animals. And one obvious difference is mastery of fire.

> 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.

Which would probably never have occurred in humans without mastery of fire. I think that mastery of fire is the common precursor of any trait you could point to as the defining feature of civilization.

Now it's possible we will find unambiguous traits of "civilization" among some other species that hasn't mastered fire (whether here on Earth or elsewhere), but until then I do believe that it is a prerequisite.

ChrisMarshallNY 3 days ago | root | parent |

I don’t remember exactly where I read it (might have been here), but Margaret Mead is quoted as saying that the earliest sign of civilization, was a long-healed femoral fracture, in an ancient skeleton. In nature, that kind of injury is a death sentence. It meant that the injured person was taken care of, long enough to heal.

Maybe we’ll find fossils, with healed “death sentence” injuries.

If anyone had ever read Lovecraft’s The Mountains of Madness, he posited a different theory about Cretaceous civilizations.

troyvit 3 days ago | root | parent |

I'd take this with a grain of Silurian Salt, but there is some fossil evidence that a Tyrannosaurus Rex or two healed from injuries significant enough that surviving them would almost require help from somebody.

The fossil of Barbara[0] "shows a particularly bad break, which goes right through the site of the tendon attachment, so most probably the tendon would have been torn off the bone [...]" If you're a very large two-legged creature a break like that could be a death sentence, but the fossilized break shows signs of healing.

Sue[1] is one of the most famous T. Rex fossils and she shows many healed injuries including broken bones and bacterial infections. It's highly possible that her species is just incredibly tough, but it's also possible that they took care of each other to some degree.

[0] https://www.iflscience.com/meet-barbara-the-pregnant-t-rex-w...

[1] https://www.newscientist.com/article/dn1393-sue-postmortem-r...

AnimalMuppet 3 days ago | root | parent | prev | next |

Why 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.

PhasmaFelis 3 days ago | root | parent | next |

Until the industrial age, I think fire was less about having more energy to work with and more about things that could never be done with any amount of mechanical power: heat, light, cooking and all its many benefits, repelling nocturnal predators, and transforming available materials in many useful ways (including smelting but also e.g. fire-hardened wood).

It did also replaced mechanical energy in some ways, e.g. hollowing out bowls or canoes, primitive mining by using large fires to crack rock faces. But I feel like those are less transformative than the other effects.

PaulHoule 3 days ago | root | parent | prev |

Also fire will be a great help in figuring out other chemistry.

There's a hypothetical alternate path where you build the "head end" of civilization using advanced biotechnology, synthetic organism, fermentation, 3-d printing and such. It's an attractive path for human space colonists but how would you figure out the genetic code without metal, glass, computers and such?

Teever 3 days ago | root | parent |

I think that we're kind of biased about these sort of things due to the limitations that evolution has placed on most animals.

We take for granted that we cannot regrow lost limbs or direct individual cells to grow into arbitrary organs as directed by our brains because we can't do it but there's no intrinsic biological reason why that must be so.

In a hypothetical first contact situation with intelligent life as we know it they may find it absurd that we can't do those things and wonder how we reached the technological level that we have despite having to spend so many resources on hospitals, work place safety and mechanical R&D instead of just growing what we need what we need it.

Our understanding of things like metal, glass, and computers would be totally different and far more implicit if we could simply grow organs or organisms that produce things for us on a molecular level if evolution had granted our brains the ability to control individual cells of our body.

PaulHoule 3 days ago | root | parent |

If a species were committed to very long survival or space travel there is a good chance, I think, they would consider making changes to their own biology.

For instance most of the places that are "habitable" in this universe are on water moons or outer solar system/interstellar bodies that have water inside because of pressure and tidal and geothermal heating. A motivated enough race could create some species (is this the right language?) that would represent itself to take advantage of these sorts of habitats.

Teever 2 days ago | root | parent |

Yeah I think that's where we're going too. Just like multicellular organisms are metaorganisms that bring all the advantages that this entails the next level will be metaspecies.

It's going to be really fascinating when we unlock the true power of single cells and an individual can use those cells to generate any sort of body type that they want or any sort of complex structure to build things out of.

Imagine structures built out of bone or enamel. It sounds kind of crazy but it isn't, We already build structures out of wood and we insulate them with wool or down.

andrewflnr 3 days ago | root | parent | prev | next |

> This tool provides access to an enormous new source of energy, which opened a myriad of possibilities unavailable to animals.

I'm not going to stand by that reasoning personally, but it's a pretty distinct change in kind.

SkyBelow 3 days ago | root | parent | prev | next |

>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.

dboreham 3 days ago | root | parent |

Language seems to me to be a gradient that extends well into other species. My cats for example communicate with me quite a bit. Even deer do so. They only have a couple of "words" but it's obvious they intend to communicate distinct concepts.

jjk166 2 days ago | root | parent | prev | next |

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.

regnull 3 days ago | prev | next |

I wonder for how long the satellites in the Earth's orbit would stay in orbit and be detectable as artificial entities.

jjk166 2 days ago | root | parent | next |

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.

hollerith 3 days ago | root | parent | prev |

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.

askvictor 3 days ago | root | parent | prev |

Like, "in the order of a billion years" very long time?

margalabargala 3 days ago | root | parent | next |

Probably 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 3 days ago | root | parent | prev | next |

Even 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.

transfire 3 days ago | prev | next |

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.

LargoLasskhyfv 3 days ago | root | parent |

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?

dvh 3 days ago | prev | next |

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)?

margalabargala 3 days ago | root | parent |

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.

henjodottech 3 days ago | prev | next |

Not a mention of Octopolis or Octlantis. Settlements of gloomy octopuses in Jervis Bay, Australia.

Liquix 3 days ago | root | parent |

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...

anentropic 3 days ago | prev | next |

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?

pvg 3 days ago | root | parent | next |

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.

JumpCrisscross 3 days ago | root | parent | prev | next |

> 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 3 days ago | root | parent |

Wait, 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 3 days ago | root | parent | next |

0.00000001% of animals are fossilized.

99.9999% of animals are extinct.

We had almost nothing, but a lot of it was inferrable.

flir 3 days ago | root | parent |

I 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 3 days ago | root | parent | 

  >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.

JumpCrisscross 3 days ago | root | parent | prev |

> thought mud was great for preserving fossils?

If rapidly and anoxically deposited. Undersea landslides and volcanoes do that. Dredging operations may, too.

flir 3 days ago | root | parent |

I really chewed up my original comment. "a mudslide or a storm" was supposed to bind to the bit about organic fossils, not the bit about inorganic artifacts.

I think "rapid" might be a relative term (I'm thinking of the Mary Rose and the Vasa). When you get to the more durable artifacts that come with a technological civilization we really should be thinking in decades, maybe centuries.

short_sells_poo 3 days ago | root | parent | prev | next |

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.

causal 3 days ago | root | parent | prev | next |

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.

namaria 3 days ago | root | parent | prev |

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.

jayrot 3 days ago | root | parent |

> There are weird structures that we discovered and haven't yet made sense of as well.

Do you mean biological structures? Or do you mean physical/geological/natural structures? If the latter, can you give some examples? Specifically of structures we haven’t made sense of that could be “intelligent design”, as you seem to be suggesting.

somethingsome 3 days ago | prev | next |

>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

cubefox 3 days ago | prev |

> 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 2 days ago | root | parent |

> If modern housing can't survive geological time, then dinosaur fossils also can't survive it.

That assumption does not hold.

cubefox 2 days ago | root | parent |

A 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 20 hours ago | root | parent |

And 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 19 hours ago | root | parent |

> 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.