[DannyB2]

If there were an industrial civilization here before us (modern humans) then it would be astonishing that in all of the fossils we have discovered, we've never yet discovered a single ancient nut, bolt, screwdriver, wrench, etc. Not one single wire or cast metal part.

As per the article, that civilization would have to predate all of the vast history of evolution that we know of. Wouldn't some higher life forms from such an earlier civilization have been in the fossil record?

[safety1st]

I think the argument goes that if the civilization was sufficiently old and short-lived, no we probably wouldn't find any fossilized evidence. For example we've only found about one dinosaur fossil per 10,000 years of dinosaur history. The dinosaurs were around for a long time, from 65-250 million years ago. Humans have only been industrialized for around 200 years. If you imagine a dinosaur civilization that's industralized for 1,000 years before it kills itself off, they still hung on 5 times longer than we have so far and yet we probably wouldn't have found fossils of their wrenches. (Not to mention that our archaeology is concentrated on places where humans lived which have little correlation to whatever might have been a good site for a dino city 100 million years ago.)

The authors of the Silurian hypothesis paper believe it's unlikely that there was an ancient non-human industrialized civilization. But they think if there was we wouldn't find its fossils. We might need to look for other markers like climate variances, radioactive materials or artifacts on the moon. Maybe some civilization arose, got stuck in the bronze age or early industrial tech for a thousand years, didn't generate those signatures, then died out. If our fossil record isn't thorough enough to find them then that possibility seems hard to disprove.

Wikipedia has a bit more detail on the Silurian hypothesis: https://en.wikipedia.org/wiki/Silurian_hypothesis

And the actual paper is here: https://www.cambridge.org/core/journals/international-journa...

[ethbr0]

In order for a civilization to be undetectable, you'd essentially bound terms in a terrestrial version of the Drake Equation [0]

You'd need a civilization that did not produce long-lived technological signatures (e.g. glass panes), that did not have a large number of individuals (i.e. produce remains), that did not substantially alter their environment (i.e. leave geographic markers), AND that did not consume easily available resources (e.g. oil/gas or metal ore).

Which is to say... possible, but not very likely.

[0] https://en.m.wikipedia.org/wiki/Drake_equation#Equation

[safety1st]

After 100 million years, would any of those signatures be detectable? Glass decomposes, only takes a million years or so. The continents themselves have rearranged so any bets about structures that still remain are off. Depletion of easily available resources perhaps, but if a bunch of iron deposits were mined out that long ago, how would we know now?

This is the topic of the paper, I think the authors settled on climate markers and radiation from elements like plutonium-239 as among the very few pieces of evidence that might still be around on that time scale. They also observe that there has likely been enough exploitable energy in the form of oil, natural gas etc. to support an industrial civilization since about 250 million years ago.

[ethbr0]

Some glass decomposes.

It's chemically inert like aluminum (after oxidizing, e.g. foil), so the processes acting on it are mechanical and subject to probability.

Some amount is going to be abraded, buried, etc, but you only need a few pieces to remain. Given their ubiquity in our culture, there'd be some somewhere.

[carlmr]

>Given their ubiquity in our culture, there'd be some somewhere.

Yet we can barely imagine a society without wheels, but some human cultures in South America didn't get that idea.

Assuming that every civilization invented glass is very tenuous.

[mbostleman]

To me the most important component is not having a large number of individuals. Which is to say there was not a large amount of physical artifacts of the tech left behind. That seems to me like there would not be enough demand to scale much tech. So it's kind of a circular problem.

[cubefox]

> For example we've only found about one dinosaur fossil per 10,000 years of dinosaur history. The dinosaurs were around for a long time, from 65-250 million years ago.

Dinosaurs presumably fossilize very badly compared to many artificial artifacts, like buildings made out of machined stone.

[withinboredom]

Man, I’ve been in castles that are less than a thousand years old that are barely recognizable. Machu pichu is a good one as well.

[inglor_cz]

Castles that stay above ground, yes, but there likely would be some buried structures, too.

Pompeii looked remarkably fresh when dug out.

[withinboredom]

Pompeii was literally buried in a matter of hours, so that’s kind of a unique case. Any underground structures would be turned into a cave from water seeping in. Most people don’t dig into the side of caves, so it’s likely we’d never know. A great example is the millennium old water passages in Afghanistan. You can’t tell they are man made any more.

The point stands, most things don’t survive all that long (in the grand scheme of things). Occasionally, the conditions are exactly right to preserve something, but there is a limit.

[cubefox]

Structures / cities might also get buried within a few hundred years due to overgrowth.

[datavirtue]

Sufficient sized meteorite impact would melt the entire surface of the planet.

[jiggawatts]

That did happen — the Moon is theorised to have formed from the ejecta of a planet-sized impactor.

However, that happened very early in the history of the solar system, likely before life had a chance to start.

[K0balt]

On the timescale we are looking at coastal areas are completely destroyed or created and substantial destruction and renewal of crust occurs. No guarantee of anything being found at all.

[cubefox]

Dinosaur fossils also didn't have a guarantee of being found. It's all in the probability.

[K0balt]

If you flip a fair coin 1000 times I guarantee it comes up heads at least once. If you set a cup on a table I guarantee it won’t pass through the table, even though both the glass and the table are mostly empty space.

Those things also are all in the probability.

[rini17]

Stone does weather too. It either needs uninterrupted dry climate (not really possible for millions of years) or being placed inside a stable geological formation (we don't usually build that way).

[cubefox]

I'd bet stone weathers many orders of magnitude less than dinosaur bones.

[JumpCrisscross]

Fossils are stone. The porous bone that housed the minerals are long gone by the time we find them.

[cubefox]

We are talking about actual bones in living animals though, and those surely fossilize (preserve over eons) much more rarely than many civilizational artifacts.

[benj111]

But we don't have any evidence for anything approaching civilisation, fair enough humans have been industrialised for 200 years, but they've been building to that point for 10s of 1000s of years.

[safety1st]

If there was a stone age dinosaur civilization that lasted for 10,000 years, what evidence of it would survive? We only even have one fossil of a dinosaur per 10,000 years of dinosaur history. They key idea is how sparse our fossil record is compared to the vastness of life's history. Plus we are talking about 100,000,000 years ago - the chance a flint or metal tool, or a stone building would survive that long and be found by us is zero or close to it.

[csomar]

It's also not far fetched. The only "remains" of the dinosaurs era are birds. These are smart animals that actually build their homes. It's possible that dinosaurs had and built homes and maybe had a small civilization.

[colordrops]

Another argument goes that they transcending to technology and form beyond what we can comprehend, covered their tracks, and left us be because we aren't interesting or to avoid interfering in our development. Perhaps our perception through the 5 senses and an understanding of reality as a physical universe of spacetime is just a short phase between being an animal and being a multidimension being.

[fsloth]

That’s basically a ”rapture” hypothesis. ”We can’t see them because of ancient technobabble sciencemagic lifted them to another realm”.

In otherwords this is a supernatural, not natural hypothesis.

In other words, that’s more of a religious rather than scientific hypothesis.

It’s cool to have inspiration from where-ever, the whole point of religion and art is that they don’t need to be scientific.

But one really shouldn’t confuse non-scientific inspiration with actual science. Confusing the two leads to arguments like earth is 6000 years old and god just faked all the fossil evidence etc.

[bmitc]

> In other words, that’s more of a religious rather than scientific hypothesis.

I get what you're getting at, but I don't think it's so clear cut. Religion is more about organizational beliefs than just beliefs. Many parts of science are pretty far fetched in terms of us only knowing a bit with a very tightly constrained perspective (humans sitting on Earth with limited technology in the Solar System in the Milky Way) but making leaping conjectures. So in fact, science and religion have some shared analogues. (C.f. Paul Feyerabend.)

Certainly, the hypothesis you replied to is incredibly far fetched. But I don't think it's religious. It's more fantasy.

[tiberious726]

It's not falsifiable, therefore not scientific

[bmitc]

To be clear, I didn't say it was scientific.

[K0balt]

TBF we are assuming that we universally know what toolness looks like. There easily could be other forms of or paths to technology that we are completely ignorant of, even to the point of being ignorant of our ignorance.

[Izkata]

A much less out-there version was in Star Trek, they built spaceships and left, bringing most/all of their civilization with them. That version was just treated as lost history, with whatever may have been left behind simply not having been found yet or having decayed over such a long time period.

[Ekaros]

Big issue with this is would any species care to do that? To clean up planet used for years, decades or centuries by decent population would be massive undertaking. Probably magnitudes bigger than getting there in first place...

[colordrops]

Downvoters; I'm not arguing for this, just mentioning one of the arguments I've heard. I was going to be explicit about this and it looks like I should have been.

[mock-possum]

Yeah that’s more of a sci-fi plot than an argument.

[DrSiemer]

Isn't it one of the more likely answers to the Fermi paradox? "Transcending" could also be "everyone got really into VR and stopped caring about actual reproduction".

[mrangle]

Where are the tools that carved the high relief sculptures at Gobekli Tepe, around 12,000 years ago?

Where are the high relief carvings that predate Gobekli Tepe, which served as the skill development toward it?

For example.

And we don't need to go nearly that far back to notice lack of ancient metal that had to exist, given what it accomplished.

Metal disintegrates fast. Megalithic evidence, at minimum and across history, implies a woefully incomplete archaeological record.

[civilitty]

> Where are the tools that carved the high relief sculptures at Gobekli Tepe, around 12,000 years ago?

Mostly flint. It's a seven on the Mohs hardness scale which is harder than unhardened steel tools.

Archaic humans have been making flint tools for millions of years.

> Where are the high relief carvings that predate Gobekli Tepe, which served as the skill development toward it?

Where to begin? Abri Castanet 35 kYa [1]. Venus of Laussel 25 kYa [2]. Roc de Sers cave 17 kYa [3]. There are countless other examples - most of them don't event have wikipedia pages.

Oldest known engravings by an Erectus are about 500,000 years old so it's been in the family for hundreds of thousands of years.

[1] https://www.archaeology.org/issues/63-features/top-10/270-to...

[2] https://en.wikipedia.org/wiki/Venus_of_Laussel

[3] http://www.visual-arts-cork.com/prehistoric/roc-de-sers.htm

[ses1984]

You’re looking for evidence of a specific thing, which is not the same as looking for evidence of anything.

[pkdpic]

I agree with both sentiments but the closer I get to primary-resource history / prehistory the more I appreciate the horrifying astronomical randomness of what is preserved / what we stumble across / what we use to cobble together our lumpy inconsistent historical narrative.

There is so much cosmic space that exists between any two historical artifacts. There's definitely room for a multitude of completely unpreserved civilizations.

On-the-nose reading that comes to mind, Of Ants and Dinosaurs by Liu Cixin... very anomalous book / quick entertaining read...

[zogrodea]

It's sometimes thought that specific questions yield the most informative results rather than general ones. R. G. Collingwood talks about this again and again in his Autobiography (which is less about the man himself and more about his thinking - quite readable).

For example, when you are debugging code, you usually have an idea of where the error might be. So the process looks like: print at line 43, is everything as expected? yes, so print at line 48 and try inspecting values at the suspected code path in search of errors.

The same detective-like work (which he calls question and answer) is used by historians and archaeologists to reconstruct historical narratives. If you don't have specific questions in your head and a way to falsify them while trying to answer a question, you likely aren't going to learn as much.

[EdwardDiego]

Serious question, do we know that metal tools were used for those carvings?

From what I recall, until iron/steel was invented, it was pretty much abrasion as bronze was not hard enough to chisel nearly every stone.

[AlotOfReading]

They were not. The primary stonework technique was almost certainly pecking [1], where you take a small "hammer" and whack it against the stone, pulverizing a bit at a time. This leaves a characteristic surface you can observe on the pillars today. However, the Gobekli Tepe builders were a bit smarter than just carving everything from scratch. They made use of the exposed limestone layers to quarry materials that were roughly the right shape and thickness.

[1] https://stonetoolsmuseum.com/technique/pecking/

[sigg3]

People who shout about ancient aliens and hidden technology always completely ignore that the people in the past had access to the most advanced machinery available: humans.

Add time to that, so that your project can have a scope of generations, passing down knowledge gained from a lifetime of doing this particular thing, the results become unsurprising even.

Amazing, inspiring and ingenious but also unsurprising.

[fsloth]

Yeah, human craftmanship can reach really, really complex heights.

I guess industrialization has made lot of people oblivious to this fact.

[mrangle]

Abrasion carved both the high relief sculptures and cut the megaliths from which they arise?

Perhaps, I suppose. I don't know enough about the physics and control of the abrasive techniques referenced. Though, I'm always in favor of emphasizing plausible variables that weaken a hypothesis.

What are the chances that abrasion work like that, hypothetically, was so specialized and unknown in 10,000 BC that Gobekli Tepe's high relief sculptures are the sole examples of that period and the earliest examples of such large and truly technical work? Nevermind the artistic skill that is reflected.

Cro Magnon was carving anthropomorphic stone statuettes in the region of modern Germany in 40,000 BC.

Food for thought: the Tell archaeological sites that dot the Fertile Crescent, which includes the Haran area (Gobekli Tepe), contain the most concentrated evidence of human technological firsts that seems to exist. Including evidence of earliest metalsmithing tech, if I remember correctly. See Yarim Tepe for a jumping off point.

So the situation is:

a. Stone carving predated Gobekli Tepe by at least 30,000 years b. The earliest known stone carvings were not in the region of Gobekli Tepe. Implying that stone carving culture and tech was known far outside of Mesopotamia, from an extremely early period. c. Gobekli Tepe's specific accomplishments are the first evidence that we have of such advanced sculpture and megalith construction skill. d. Metalsmithing arose in the immediate regions and cultures that included the area of Gobekli Tepe.

So on one hand we have widespread tech suggested to be responsible for the first evidence of highly technical stonework that is limited to one area in this early period of pre-history, and on the other we have specific advanced tech (metallurgy) that is best for such technical and large scale work arising out of that same area.

It could be a coincidence, but arguably it would be a large one.

[inglor_cz]

Metal is too precious to be just abandoned. Metal is usually recycled, even in our civilization.

Whatever metal objects from ancient civilizations we know, are either grave goods (swords of warriors etc.), or were found in shipwrecks etc., or were found in destroyed settlements, plus a few accidentally lost (fell into a well etc.). But most metal objects get recycled.

[EdwardDiego]

That's a very good point.

[siriaan]

The bedrock around Göbekli Tepe is apparently limestone, so saith Wikipedia, so no, metal is not required to carve it.

[dr_dshiv]

Stonehenge is much harder stone—and carved from “hammerstones.” Crazy the effort it took.

[hooande]

This assumes that their technology would be similar to ours. They could have used biological mechanical parts, made from plant or animal material. They could have had radically different theories of mechanics or construction that better fit the state of the planet at their time.

In general the statement "They couldn't have been civilized because they aren't exactly like us" limits what we look for and how we look for it.

[notahacker]

The statement "they couldn't have been civilized because they aren't exactly like us" is a straw man though

The actual question the article posits is "Could an Industrial Civilization Have Predated Humankind?", and so it seems logical to take evidence of industry as a starting point to answer that question. A mere couple of hundred years of human industry has moved vast quantities of matter about, created many new types of molecule, demonstrably altered the climate and filled sediment beds with objects far more eyecatching and likely to be preserved than the dinosaur feathers and skin prints and footprints we've found fossils of. An industrial civilization need not regard combustion engines as the most useful power source, prefer wheels to gliders or think straight lines look cool, but it does need to be characterised by some sort of industry.

A hypothetical species of dinosaur that spent its life writing beautiful poetry, studiously avoiding dropping its organic tools anywhere they might be fossilised and generally being content enough with its life to not try to remake the planet for its convenience might even be more intelligent and cultured than us, but it wouldn't be an industrial civilization.

[kragen]

a human brain contains 100 trillion synapses each transmitting a signal of about 100 bits per second, and weighs 1.3 kg, for something like 10¹⁶ bit operations per second, 8 × 10¹² bit operations per second per gram. the cpu i'm typing this on weighs about a gram and has four cores, each of which typically manages about 1.5 64-bit operations 2.6 billion times a second, about 10¹² bit operations per second and also about 10¹² bit operations per second per gram. evidently the brain tissue is about an order of magnitude more computationally powerful per unit weight, and as it happens it also uses an additional three or four orders of magnitude less energy per unit weight. manufacturing it is also much cheaper. if we knew how to program it, we'd probably program globs of neurons rather than the very fine photolithographic microelectronics we are using today

neurons, however, fossilize very poorly indeed; after death they typically liquefy within days, losing all of the structure that could betray how they functioned

the particular shape of our industrial civilization is based on mass production in centralized facilities of durable goods that are identical to high precision (deep submicron precision in the case of this cpu). clearly this is not the only possible way to produce massive abundance; the rain forest or even the corn field does not work this way, but produces much more detail than tsmc does

much of the durability and fossilizability of our conventional technology stems from its stupidity. to remain standing, a two-story house would once be made with meter-thick walls, while modern hollow brick with plaster and reinforced concrete reduces this to perhaps ten solid centimeters between indoors and outdoors. more frugal balloon-frame designs consist entirely of metastable materials like wood and steel, materials which will lose their structure if left exposed to air and water, either suddenly in a fire or gradually over decades. but even a balloon-frame house is wasteful and inefficient compared to a five-meter-tall stand of bamboo

remaking the planet for your convenience is much cheaper if you can avoid spending resources on durability and fossilizability which don't benefit you during your lifetime

could you get there without a transitional phase of making lots of thick, solid objects out of materials that are stable on geological timescales? probably, but maybe not if your uplift path starts with fire instead of math...

[thrashh]

That’s possible that they don’t have the same materials as us but they would have the same problems.

Take plastic or metal. Their main draw is that they do not decompose or degrade. There are a billion problems that can be solved when you have a material that does not naturally degrade or decompose.

So even if this civilization did not use plastic or metal, I find it hard to believe they didn’t come across a problem that needed a stable non-self-destructing material, which would then have been left behind for us to discover now.

It’s not feasible to build anything advanced if all your materials naturally decay.

It’s true that there are fewer decomposing organisms the farther back you go, but you have to go way way back to a point where the chance of intelligent life existing is pretty low.

[mrangle]

Absolutely metal and plastic decompose and break down, respectively.

[inglor_cz]

Not all metal. Buried gold retrieved from ancient graves looks very "fresh".

[MichaelZuo]

After ten million years even a large gold ingot would entirely be subsumed by the surrounding matter. Assuming a 10 nanometer/year erosion.

[jiggawatts]

Also most of the noble metals would remain pristine: platinum, iridium, etc…

[userbinator]

The latter, back into oil.

[thrashh]

Sure, but on very long timescales. And eventually once you make enough of it, it gets lodged in all sorts of places, some less susceptible to decomposition, such as humans in bogs or mammoths in glaciers.

I just find it hard to believe there to be not a single trace of anything.

[AtlasBarfed]

Eh, industrialization is heavily dependent on metallurgy.

What is the word industrial? Metallurgy, mass production, interchangeable parts, and the steam engine. Materials, tools, efficiency techniques, and energy.

The other aspect of industrialization is the sheer scale of it.

Honestly the only thing that comes close IMO is a lot of the cellular mechanisms. It uses materials in novel ways, efficient protein devices, and ATP energy. But I don't think it would scale to macro levels.

Maybe you could squint and look at ant/insect colonies?

[dheera]

Maybe, but on a planet that's full of rocks one would think they would have at least organized a FEW of the rocks into structures of sorts.

[manfre]

Mountains can turn into a flat landscape in a geological timespan. It's also possible we've uncovered the signs of these type of ancient structures and didn't recognize them as such, used the materials to build something during our past, or pretended we didn't recognize it in modern times because that would have slowed/stopped a construction project.

[fuzzfactor]

>"They couldn't have been civilized because they aren't exactly like us"

Well if you go back to the dawn of Homo Sapiens that's quite a ways back, but then you could rearrange that concept to say "they couldn't have been that uncivilized because they were exactly like us."

Oh, wait a minute . . .

[SiVal]

If they were so advanced that they left the ordinary material world behind, then anything is possible. Otherwise, they would probably be like us in the sense that their in-use technologies would span every level from lowest to their own highest. As our tech improves, we continue to use the wheel and shaped stone and conrete, iron, steel, glass, knives, ceramics, etc. We still use things that are pulled out of the ground (like our distant ancestors) while also using the latest AI algos.

So, a very wide range of "industrial civilizations" would be expected to leave behind lots of basic natural materials in artificial forms. Their basic natural materials would be about the same as ours because they are found in nature and not very diverse (compared to high tech pharma chemicals or digital algos), so we ought to be finding lots of evidence of pre-human low(ish) tech, even if they were quite high tech.

[andsoitis]

> biological mechanical parts

What’s that?

[swores]

A wooden cog, a chain made not from metal but from plant fibres, etc etc.

[andsoitis]

And you’re thinking that the machines that produces these plant based parts at industrial scale were themselves made of plant material, rather than plastics and metals?

What do you postulate were the power sources such an industry would have used?

[marginalia_nu]

To be fair, there are entire human civilizations we know have existed that we barely have archeological evidence to make sense of. We know they had language, culture, technology and we've found shells, bones and rubble.

That, and the fact that we've found one antiktythera mechanism and nothing like it before or since raises questions. It seems implausible for a culture to produce a singular advanced mechanical computer with no precursors and then stop and never make anything like it again.

[giantrobot]

> It seems implausible for a culture to produce a singular advanced mechanical computer with no precursors and then stop and never make anything like it again.

A culture didn't create it. A person or team created it. The Antikythera mechanism was built before the ISO 9001 specification so its documentation may not have survived long past its creators lives. The high precision manufacturing required, in an era before high precision was all that precise, suggests the mechanism was likely a rare artifact. It was dumb luck it was found in the first place.

There's likely many complicated ancient devices lost to time because they weren't widely available or described in documents that have persisted. You literally run a search engine for marginalia that may not be popular or widely known. It wouldn't take much to knock a lot of that content off the web and be lost to history.

[marginalia_nu]

> There's likely many complicated ancient devices lost to time because they weren't widely available or described in documents that have persisted. You literally run a search engine for marginalia that may not be popular or widely known. It wouldn't take much to knock a lot of that content off the web and be lost to history.

Well that's my point. Not that the greeks had some forgotten industrial revolution, but that archeological records are very limited, and we were a stroke of dumb luck away from never discovering the antikythera mechanism. It raises the question of if we almost missed this, what else did we miss. Not just in greece but elsewhere too.

[tyg13]

To the contrary: the fact that only one ever was found, to me, suggests that it was the work of one brilliant mind whose work was not understood or continued by their culture.

[marginalia_nu]

Even if it is a single creator, does it seem realistic that this was the first and only machine they built?

[throw47474777j]

I’ve heard it argued by historians that there were likely to have been multiple prototypes of the antykythera mechanism, but each one was recycled to produce the next.

[fuzzfactor]

>each one was recycled to produce the next.

This could lend itself to the idea that one person made it, and if nothing whatsoever like it had ever come before you have to figure it took an awfully long time for one person to create something this complicated single-handedly.

Could be a number of years between iterations in a continuous improvement process that adds up to something like a life's work.

Maybe also could be passed down to a subsequent individual like a very specialized craft, and build technology across generations.

[mrangle]

Given the tech that is the product of multiple major breakthroughs, I'd rate that to be doubtful.

While I don't think that the following implies that robots existed, to my above point recall that Talos of Greek Myth is a robot.

Which does imply that the concept of such tech was shared across the entire culture. Which, in turn, suggests that related tech is less likely to be the product of one mind.

[masklinn]

Literally the entire SF genre is based around creating stories of things we’re unable to create.

Extrapolating automatons only requires having basic concepts of mechanical automation, which the Greeks very much had.

The idea of space flight predates powered flight by centuries.

[BuyMyBitcoins]

I figure that any industrialized civilization would have left indirect evidence of itself by mucking up the fossil record with introduced species. We intentionally and unintentionally introduce plants and animals far outside their natural range.

https://en.m.wikipedia.org/wiki/Columbian_exchange

You would see some species inexplicably take on a worldwide distribution, or see species suddenly turn up on far away landmasses with no good explanation.

https://en.m.wikipedia.org/wiki/Chorioactis

The link above is fascinating, but I do not think it is evidence of any past civilization. This probably happened naturally, but it does seem exceedingly rare. If there were a past industrial civilization there would probably be tens of thousands of examples like this one.

[naasking]

How many introduced species are there as a percentage of all existing species? This seems like an important number to calculate the probability that we might have missed such an introduced species given the fossil record we have.

It could also be that introduced species are less likely to be found in the fossil record for whatever reason.

Then again, maybe we have found such a thing but haven't recognized it for what it is due to missing context.

[BuyMyBitcoins]

That’s a good point, and I don’t have an answer. In my mind I was thinking of more obvious examples, like camels being introduced to Australia. Or cichlids from Lake Victoria being introduced into isolated lakes in North America. The idea being that you would notice some very obvious out-of-place fossils.

I also assume that these species, often invasive, would outlast the civilizations that introduced them. So you could probably also infer some of this by looking at descendant populations.

[naasking]

We would naturally just assume that the same species appearing in different places just implied that those places were closer together in the past + migration. And so we have Pangaea before continental drift.

If we lacked progenitors of those species in some places, we would just call it a temporary gap in the fossil record, of which we have many.

We're pretty good at inventing explanations. Eventually these gaps might start looking conspicuous, but I'm not sure if we're at that point yet.

[melagonster]

but we have good prove of continental drift now. before we getting enough evidences, this theory just a joke.

[naasking]

You've missed the point, because these theories are basically compatible with the existing evidence, they just tell a different story.

[inglor_cz]

"are there as a percentage of all existing species"

Percentage of total biomass is more interesting. The more (and bigger) bodies, the higher the likelihood of being fossilized.

[SubiculumCode]

Interesting thought. However, one of the ideas that the article brings up is the extreme undersampling problem of fossil records. Its conceivable that a 300 year blip->catastrophe would be missed entirely in the fossil record.

[tetris11]

> You would see some species inexplicably take on a worldwide distribution

Im reaching here, but: https://en.wikipedia.org/wiki/Cat_gap

[redandblack]

Obligatory Pratchett reference - https://en.wikipedia.org/wiki/Strata_(novel)

[greatfilter250]

> worldwide distribution

Why does an industrial civilization need to be global?

Our industrial civilization appeared extremely quickly, perhaps in the past 300 years, but it happened to appear within a preexisting global trade and travel network. An industrial civilization which existed for a few hundred years, outside the context of such a network, might not ever see the need for one.

[Nasrudith]

Industrialization would increase demand for raw materials and heavily encourage expansion even if not required per se. Self-sufficiency of a single area becomes more difficult as technological complexity rises as well. Let alone demand for the "exotic" materials like rubber or even bronzemaking needing tin for their copper or visa versa. (The two seldom occur within different geologies seldom close to one another.)

[inglor_cz]

If the beings that created it were capable of living across the globe, and not limited, say, to the equatorial region, it is somewhat likely that such civilization would diffuse much like human industrial civilization did; older, less efficient societal structures would be unable to compete with it.

[ElFitz]

I recall someone asking on World Building StackExchange what aliens could find in a few tens of millions of years or so if the human race were to disappear today [0].

The answer was "not much", aside from discrepancies in metals distribution, with intriguing concentrations of iron oxyde, nuclear waste, or gold.

I am aware it certainly isn’t the most scientific or authoritative of sources, but they made interesting points.

[0]: https://worldbuilding.stackexchange.com/questions/117267/hum...

[pvaldes]

> What aliens could find in a few tens of millions of years

Much more than we are finding. The earth would be a mess with plenty of really puzzling events.

Wild tomatoes with narcissus and flounder genes for example.

Sudden extinction of entire groups of animals and plants in only a few thousands of years

Radioactivity holes and missile holes fossilized with metals in the bottom

Cities, and cemeteries in particular, would be a geological nightmare waiting for an explanation. A collection of grey granite from Canada carved in lames of uniform thick, polished for no reason and accumulated in a point. At 20 meters away another set of lames of Chinese black granite and 30 meters away a lot of yellow marble only known from Italy. All wrapped in asphalt, gravel, glass and concrete. Dumpsters would also be very strange places with plenty of plastics and chemicals that shouldn't be there.

Gems also. Diamonds carved in impossible shapes all ending in a more or less conical tail in the whole planet. Lots of things shaped like a heart. Strange collections of elements with unique properties of the periodic table found always together: Mixed minerals found near, gold, silver and platinum, at tens thousands of Km far away from its known mines. As they are often saved in fireproof boxes, would had survived miraculously in burnt areas.

Implants. Titanium fossils shaped like the femur of an animal (and always the same animal) and porcelain teeth would be enough to show a civilization and signal us in charge of it.

[defrost]

As of last Tuesday, the mark of human indistrial and technology activity on Earth is officially marked in the geological layer:

Welcome to the Anthropocene, Earth's new chapter (phys.org)

https://phys.org/news/2023-07-anthropocene-earth-chapter.htm...

    Since 2009, a cloistered band of hard-rock geologists and other scientists have toiled on a mission of great consequence.

    On Tuesday they will deliver the last of their findings—the location of ground-zero for the Anthropocene, the proposed geological epoch borne of humanity's outsized impact on the planet.

How the weight of the world fell on one geologist's shoulders

https://phys.org/news/2023-07-weight-world-fell-geologist-sh...

    Zalasiewicz pointed to an "embarrassment of riches" of evidence locked in ice cores, sediment and coral skeletons: microplastics, forever chemicals, traces of invasive species, greenhouse gases, and the fallout from nuclear bombs.

Proof humans reshaped the world? Chickens

https://phys.org/news/2023-07-proof-humans-reshaped-world-ch...

    When aliens or our distant progeny sift through layers of sediment 500,000 years from now to decode the Earth's past, they will find unusual evidence of the abrupt change that upended life half-a-million years earlier: chicken bones.

reply

[krior]

The announcement described in the first link (unfortunately in german): https://web.archive.org/web/20230714101242/https://www.mpg.d...

[JackFr]

One hundred million years is a long time for a screwdriver.

[getmeinrn]

Random thought, but if we extrapolate the path we're on in terms of biodegradability and sustainability, it's not ridiculous to assume that a very advanced version of us would have developed the technology and legislation to ensure that all products biodegrade safely within X years.

[blueflow]

This doesn't undo all the stuff that already is in the ground and rivers everywhere.

[FredPret]

After a long time hanging around, some organism might evolve that eats it though

[TechBro8615]

Or a second industrial civilization would use it to power their cars...

[blueflow]

Which happened for all fossils already and they are still there.

[FredPret]

Fair point, although not all of them, and not all of those that do remain. If styrofoam ever starts rotting, maybe the styro-philes will eat 100% of each cup and poop out only completely normal organic matter. Nobody will ever find it!

[hutzlibu]

Can we develope such a microorganism please?

[ekianjo]

Still all there compared to what quantity exactly? Ever hard of the gazillions of fossil fuels?

[blueflow]

They still are there to detect them. The question was whether our fossil records would be detectable.

[c22]

Perhaps there could follow a movement to undo all prior impacts out of an ethical motivation.

[mc32]

And retroactively apply that technology to all the previous garbage they produced and their predecessors produced too?

Sounds like they invented the magic wand.

[markus_zhang]

The only possibility is...they sank into deep ocean. But then it's going to very unlikely that nothing surfaced for the last 20k or so years. So you have to throw a valcano or a large meteor on top of them, which would require even more proofs.

[mrangle]

There are megaliths under water, off of the coast of Israel. Not natural rock formations that look like such, but confirmed and clear megaliths of the rock circle type that is all over Europe as well as in Israel and elsewhere in the Near East.

[tarikjn]

Not pre-human but challenging the understood modern human timeline of industrialisation — We have not found the tools, but we may have found the products; in the form of stone-based vases that archeologists attribute to the Early Egyptian Period but are believed to be from much earlier, and would have required tools that have not been discovered yet. The channel UnchartedX make a compelling argument about this hypothesis: https://youtu.be/ixTTvRGk0HQ

[AlotOfReading]

What a silly video. The argument he's making is called a unilinear teleology. History is not an arrow-line march from less advanced to more advanced, and it's incredibly common for the apparent workmanship of artifacts to "regress" as styles and intentions change over time. Just look at all the people who complain about modern art because "classical takes more skill".

Also, there's essentially nothing you can't do with stone given primitive tools, sand, and a shitload of talent/time. One thing about ancient people is that they had all of these in abundance. Making arguments from the position of "they couldn't have done this with the tools they had" is almost always wrong because it's coming from a modern perspective of how tedious and uneconomical it'd be to do it today.

[tarikjn]

As someone who works with manufacturing, I don’t think it’s silly. Precision is not just a function of time available, manpower and talent, but also tooling technology. Manufacturing a single replica with today’s technology is believed to be challenging — and has not been attempted yet — but hopefully someone will take the challenge soon. There are no serious claims that these can be made with known ancient technology and time+manpower. Your response is often the response of people in archeology who do not understand precision manufacturing with hard materials, and shows how underrated these artifacts are.

[AlotOfReading]

This is not modern precision manufacturing and metrology, it's abrasively grinding down rock that's been roughly shaped. It's tedious as all hell, but well within the toolbox for ancient Egyptians (not to mention many other societies). There are a lot of options to do the rough shaping. Egyptians are known to have used abrasive drills for some artifacts, but other cultures often used rocks of the same or greater hardness as chisels alongside other mechanical methods for rough shaping.

Again, you can do this to shape virtually any rock. Stonemasons don't do this today because it's excessively annoying and slow. It's not a coincidence that khafre enthroned is a royal piece for a wealthy and powerful pharoah.

[tarikjn]

The rough shaping is not at issue. The challenge is maintaining tolerances along all axis and constraints on your detail work while using high forces and pressures to work the hard material. Grinding is a good guess for the possible material removal process — and it is up there today for the smallest tolerances using a mechanical process —- watch a video of a jig grinder in action. But what tool is used to hold or insert the sand aggregate at the pressure point? Are you suggesting that the vase is turned? That turning tool would need precise bearings itself to maintain that precision. According to archeologists, Egyptian didn’t even have the invention of the wheel yet at this point. These are all questions that people are looking for answers, and the best way will be to attempt to reproduce an artifact using various methods. I sincerely invite you to contribute by trying to elaborate the entire process that would enable this.

[agentgumshoe]

I assume back then they weren't too fussed about having 100 people work on a small rock should they desire.

I think we just don't comprehend, as mentioned above, how much time and effort could be allowed for back then. I'm sure 100 people could create a near perfect vase given 30 years to work on it (random example).

[gizajob]

Have you ever ground one to prove this?

[AlotOfReading]

I've polished things with sand before and used hammerstones, yes. I'm not a stonemason though, just somone who spent a lot of time as a kid playing with rocks.

Most people will have some familiarity with emery cloth/sandpaper, which are basically the same principle. We don't even need to look at fancy egyptian statues. Carnelian beads were a common trade item across the Ancient near east and Egypt made this way. It's not magic.

[Starwatcher2001]

Amateur telescope makers can make glass mirrors accurate to 1/10 of the wavelength of light using very simple tools and processes.

https://www.bbastrodesigns.com/JoyOfMirrorMaking/Intro.html

[yesco]

> Also, there's essentially nothing you can't do with stone given primitive tools, sand, and a shitload of talent/time

How absurd! Skill and craftsmanship can get you far, but they will not allow you to craft with such precision that it's imperceivable to the human eye, how could they even verify their efforts? The video, while long, presents dozens of well structured arguments with strong evidence, your dismissal comes off as extremely arrogant and foolish in comparison.

[lumost]

Pre-history is tough. Outside of written accounts and a few major cities cited in particular environments - there isn’t a lot of evidence about what humans were doing for 100k years before the Roman/Chinese empires formed. Even Egyptian history is pretty spotty.

We know there were civilizations in North America such as the Mississippi River valley mound builders - but our knowledge tops out at “they existed”. It would not surprise me if agrarian civilization rose and fell multiple times due to climate change.

[_aleph2c_]

Maybe we should look off planet, look to the Lagrange points: https://en.wikipedia.org/wiki/Lagrange_point

We might find some old equipment from an elder spacefaring species. If we don't find anything, maybe we should leave some human monuments out there so the next civilization can know about us.

[roseway4]

As the Wikipedia article mentions, we’ve already done just this with the JWST…

[NavinF]

Naw the JWST won't stay there after it loses power.

> The points L1, L2, and L3 are positions of unstable equilibrium. Any object orbiting at L1, L2, or L3 will tend to fall out of orbit; it is therefore rare to find natural objects there, and spacecraft inhabiting these areas must employ a small but critical amount of station keeping in order to maintain their position.

[jamiek88]

Nothing will. The Lagrange points are only quasi stable.

[Scramblejams]

Lagrange Point orbits still require station-keeping. Anything 'parked' there will eventually float away from it, unless the position is actively maintained.

[andrewprock]

There is tons of archeological evidence dating back to the last ice age, roughly 10,000 years ago. Before that, there is ample evidence dating back to the middle paleolithic identifying cultural traditions including art, music, and ritual.

[lumost]

Ample is debatable. We have biased evidence from specific biomes and regions. We are restricted to artifacts that survived from this period - effectively tusks, rocks, and specific forms of art.

[WalterBright]

I recall TV shows saying that the Egyptian pyramids could not have been constructed with Egyptian technology, so it must have been space aliens. The same for the closely fitting stones in Inca buildings.

It doesn't take advanced technology to do either of those things.

My favorite one was pi is there in the relationship between the pyramid base length and its height, and the Egyptians had no notion of pi. Again, space aliens! But if the Egyptians used a wheel 1 cubit in diameter to mark out the base, and the height was in cubits, then there's pi.

(What's a cubit?)

[prime17569]

This reminds me of this video by engineerguy that discusses the use of heuristics in engineering: https://www.youtube.com/watch?v=_ivqWN4L3zU

[umlautae]

Not sure if irony but cubit means a unit of length from an elbow to the end of the fingers. (BTW maybe that’s why people think giants were 100 cubits tall, when in fact the text said they were a group hundred hands strong)

[WalterBright]

It's a joke from a famous comedy routine where God tells Noah what the dimensions of the arc should be in cubits. At the end, Noah asks "what's a cubit?"

[mrangle]

Both can be true that it took more advanced tech than they are credited and it wasn't aliens.

[WalterBright]

The simplest explanation is the most likely.

[FollowingTheDao]

You were assuming that their industrial civilization would look anything like ours. Why do they need nuts and bolts? Why couldn’t they have use some natural form of biodegradable materials?

[hutzlibu]

Then they made some leaps.

Casting iron(copper) is relativly easy and powerful.

Experiment with hot things in fire and you will discover it after a while.

"Why couldn’t they have use some natural form of biodegradable materials?"

Like bones for bows and spears? Humans did that, but metal is apparently more effective and useful.

[RecycledEle]

I would not say there has never been a single ancient thing discovered. There are many anomalous findings in archeology.

Here are a few examples: * https://en.wikipedia.org/wiki/London_Hammer * https://en.wikipedia.org/wiki/Coso_artifact * https://en.wikipedia.org/wiki/Nazca_Lines * https://en.wikipedia.org/wiki/Yonaguni_Monument * Parts of the Egyptian Pyramids seem to have been cut with circular saws. * Places in the ancient world seem to have been nuked, including the ancient city of Sodom. * Some ancient maps are amazingly accurate, when they should not have know the shapes of land masses.

I'm NOT saying any of this proves the Silurian Hypothesis. I looked into some of these claims, and realized how hard it is to be an archaeologist. The amount of stuff left behind is small, and you can never be sure who did what to it over the centuries.

Artifacts are not stored in hermetically sealed containers until archaeologists dig them up. Instead, artifacts mix with their environments for centuries. This mixes up the carbon and makes carbon dating iffy at best.

I classify archaeology as a pseudo-science.

[tanuki]

Aren't there lots of testible hypotheses in archaeology though? I get that you're saying that a lot of explanations feel speculative, but it feels a bit far to say the field itself is incompatible with the scientific method.

[RecycledEle]

The Scientific Method is: "Scientists (and other people) can then secure, or discard, their hypotheses by conducting suitable experiments." https://en.wikipedia.org/wiki/Scientific_method

If my hypothesis is that pottery will look like this after being buried for 2,000 years, how do I test that? I don't have 2,000 years before I need to publish.

[MR4D]

If it were more than 65 million years ago there would be no evidence due to plate tectonics destroying all evidence. Still could be on the moon or another planet though.

[Barrin92]

There would be no evidence on the surface of the earth, but just as there's characteristic fossil layers in the ground there would be evidence in the sediment. Right now about 30 billion tons of concrete are used by our species every year. If there were industrial civilizations of that scale, you'd have a whole stratum of very obvious artificial origin between the rocks.

Also some leftovers of the nuclear industry. Enriched Uranium does not occur in nature but U235 has a half-life of about 700 million years. So remnants of our nuclear activity will be detectable for a long time.

[flangola7]

We have fossils of cyanobacteria from 3 billion years ago. There's plenty of dinosaur fossils that are 100+ million years old. We definitely could have found something.

[paulryanrogers]

We still have fossilized bones that old and older. And even if they had corroding tools there would likely be cast fossils proving their existence.

[barelysapient]

I like to wonder what undiscovered fossils exist below the oceans that cover 70 percent of our planet.

[blueflow]

Look up about continental vs ocean crust, ocean crust is younger and has a shorter lifetime. You have better chances finding maritime fossils on land.

[jamiek88]

Yeah subduction is the missing key that took a while for us to understand. Ocean crust is young.

In fact most earthly rock is relatively young.

Plate tectonics was such a clever idea. So obvious now, I mean just look at a map of the world of course continents were once one, you can see where they join, like a jigsaw puzzle.

It astonished early western explorers finding seashells on mountains!

[DavHeheCuddly]

or maybe all the continents were once one because it was just the full surface of an expanding planet

[mc32]

It's one of those "prove a negative" but with the enthusiasm of flat-earthers. Is it technically possible there could have been an isolated population that evolved and emerged and then got engulfed by a supervolcano or was taken under by a sudden asteroid impact or ... and all traces erased? We can think and work out such scenarios, but they are not likely at all.

[jboogey]

A great Atlantic article explaining how current human civilzation might appear in a fossil record in the distant future https://www.theatlantic.com/science/archive/2019/08/arroganc...

[zakki]

OOT but same vibes, this same reasoning is used by Creationist as well. If evolution happened, why don't we find more and more fossils of the intermediate form? Until now we only found final result of the evolution. And some hundred million years animals still exist, i.e. Coelacanth.

[IAmGraydon]

Not sure what you're talking about here. There have been many thousands of fossils found at various stages of evolution. Human evolution alone has a wealth of examples, and this is not new:

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

[coredog64]

There’s a Sci-Fi series that explores a technologically advanced ice age civilization that built with water/ice and hydraulics. The current protagonists couldn’t figure anything out because all that was left was tiny bits of corroded metal.

[SubiculumCode]

The article indicated that surface turnover could have removed that evidence.

[topspin]

And yet we have 3.4 billion year old cyanobacteria fossils.

[zen928]

yep. these kind of thought experiments are cute but it's so easy to just immediately dismiss bad science that wants to ignore historical record to write paragraphs of fanfiction

the main crux of these arguments always depends on how it's hard to prove something didn't happen without exact historical evidence for every single organism in every single recorded geologic period, which is a terminating thought to actually holding a rational conversation. OK, cool, then we also: live in a simulation, are observed by aliens or influenced by aliens, move to alternate realities every time we sleep, etc. wow, so "interesting"!!

[newZWhoDis]

Various sci-fi has explored this idea, for example Mass Effect, but “Reaper” species could explain that.

[topspin]

Also aliens. I see.

[Mountain_Skies]

If that were the case, perhaps someday we will find evidence on the Moon or elsewhere in the Solar System that an earlier civilization achieved space flight before they were erased from Earth and unable to establish a permanent foothold elsewhere in our corner of the cosmos. The Moon and other celestial bodies in the Solar System of course have their own processes that erase the surface over time, but at least with the Moon, it does appear to be a far slower process.

[Simon_O_Rourke]

Lets not forget all their detritus and trash too - as well as any industrial waste... that stuff would have shown up long long ago if it in fact existed.

[analog31]

Any such civilization would have to have been configured to leave no traces for us to discover. Russell's Teapot comes to mind.

[thrashh]

That species would have to be completely united and able to collude without a single disagreement.

Not only that, they would have had to achieve complete perfection because we haven’t found a single trace.

[pragmatic]

Read the article.

[ekianjo]

What do you know about the preservation of metal in fossil layers over millions of years?