From author and druid John Michael Greer's essay, "The Next Ten Billion Years"[1],
"One hundred million years from now:
The universe has a surprise in store for the corvins, though. Their first moon landing included among its goals the investigation of some odd surface features, too small to be seen clearly by Earth-based equipment. That first lander thus set down on a flat lunar plain that, a very long time ago, was called the Sea of Tranquillity, and so it was that the stunned corvin astronauts found themselves facing the unmistakable remains of a spacecraft that arrived on the moon in the unimaginably distant past.
A few equivocal traces buried in terrestrial sediments had suggested already to corvin loremasters that another intelligent species might have lived on the Earth before them, though the theory was dismissed by most as wild speculation. The scattered remnants on the Moon confirmed them, and made it hard for even the most optimistic corvins to embrace the notion that some providence guaranteed the survival of intelligent species. The curious markings on some of the remains, which some loremasters suggested might be a mode of visual communication, resisted all attempts at decipherment, and very little was ever learnt for certain about the enigmatic ancient species that left its mark on the Moon."
I can't speak to dinosaur people, but the population genetics of our own DNA reveals that there were never many humans on the planet till recently, so that rules out any very large human civilization. (Unless they genetically altered themselves to hide the evidence! Ahaaa...)
If whole populations were wiped out and the world was repopulated by a small remnant would that not account for it? Or if an extinct human species had an advanced civilisation?
The founder effect differs between small populations filtered from a large population vs a smaller parent population.
I want to point out that the silurian hypothesis is specifically about civilizations removed from us by geologic time. Advanced human precursor civilizations are much more effectively ruled out by the current evidence. Basically, a hypothetical precursor society either has to look very different from any we know about and materialize out of nowhere like alien colonists, or they didn't exist.
For example, we know they weren't using large amounts of fire because nothing in the global charcoal records points to that. We know they weren't using plants that produce pollen because we don't find phytoliths with domestication indicators. We know they weren't using surface metals, because there was lots of that still around when the classically ancient civilizations started. We know they didn't contribute significantly to the gene pool. We have no material culture from them. We don't have a location on Earth they would have lived in. Etc.
I think there is no evidence for it, but I think the point of the Silurain hypothesis (which the article does not convey well) is that if there were such civilisations we would not know as its unlikely we would find any evidence.
This article is a weird mash-up of an actually very interesting paper [0] with random personal slop like i've asked my rabbi, consulted my kabbalah-initiated friends and for the fun mixed it up with some fashionable ancient text (Mahabharatha)
So maybe just stick right to the paper itself and its clearly stated motivation?
> Perhaps unusually, the authors of this paper are not convinced of the correctness of their proposed hypothesis. Were it to be true it would have profound implications and not just for astrobiology. However, most readers do not need to be told that it is always a bad idea to decide on the truth or falsity of an idea based on the consequences of it being true. While we strongly doubt that any previous industrial civilization existed before our own, asking the question in a formal way that articulates explicitly what evidence for such a civilization might look like raises its own useful questions related both to astrobiology and to Anthropocene studies. Thus, we hope that this paper will serve as motivation to improve the constraints on the hypothesis so that in future we may be better placed to answer our title question.
Yes. We'd find mines, where the richest veins were mined out and what's left is spread in a pattern that clearly appears to be "a rich deposit but with the best stuff taken already". The mine itself would have long collapsed but would also leave interesting evidence, a pattern of mismatched geological layers that rather than looking like an earthquake or a tectonic upheaval would be something that is relatively clearly shaft-shaped and if followed into the mountain would open out into a pattern that indicates intelligent mining activity as the anomaly is further charted.
Places where there is suddenly a vast collection of foreign rocks from the other side of the world that can't be explained by glaciers.
Radioactivity from nuclear tests that can't be explained by stellar phenomena and leave a layer of weird isotopes and isotope ratios all around the world, as we already have done.
And while we aren't to the point we'd have found this quite yet necessarily, evidence on the Moon where unlike Earth evidence probably would in fact persist for millions of years, especially if it ever attained any scale, e.g., "a large complex of cities" might still leave a visible mark on the surface easily visible to modern satellites and clearly with no other explanation available as to what caused it.
People get stuck on the idea that the only way to determine there was intelligent life earlier is to find a super complicated artifact which obviously can't survive, but there are footprints we've left in the world that are way, way larger than a cell phone or even a major city.
I don't find it hard to believe we've lost entire human civilizations. In fact I'd call it the smart bet. Maybe those civilizations were even a bit more sophisticated than we'd have thought, with maybe an earlier and entirely unknown Iron Age popping up somewhere for some period of time or something. But this is the first major technological civilization this planet has ever seen, even across geological time scales. And those lost human civilizations never reached to the level where they took all the easy resources like we have, because if they had, we wouldn't be able to get them. Some resources we call "non-renewable" do replenish on a few million year time scale, but we also pull lots of resources out of billion-year-old rocks, such as copper mines in northern Michigan which are pulling resources out of pre-Cambrian rocks. Clearly nobody else has been there, at scale.
The exception that proves the rule is a nuclear reactor from Gabon that dates to 1.7bn years ago... and which was clearly natural, a uranium-rich cave got flooded and went supercritical: https://en.wikipedia.org/wiki/Oklo
Of course we haven't discovered everything. But it seems very likely that if there were a civilization's worth of slag from 500m years ago, we would have discovered it.
A more interesting question is the civilizational technology of domestication, especially since that is short-term technology coupled with long-term evolution. It does seem possible (but purely fantastical) that Earth had talking dinosaurs with sophisticated ideologies and mythologies, feeding dumber dinosaurs and curating the growth of nutritious plants, the descendants of which all died 65m years ago.
> People get stuck on the idea that the only way to determine there was intelligent life earlier is to find a super complicated artifact which obviously can't survive
Why is it obvious that none of them can survive? Ordinary bones can become rocks (fossils) that are preserved. If mining of iron ore is visible, things would have been made out of iron -- wouldn't a large structure made out of iron leave some trace? Or even a small one? Why are there dinosaur fossils galore, but not so much as a pre-human fidget spinner to be found?
Not really, because none of this passes the smell test if you know even a tiny bit about geology and paleontology. The most solid arguments are religious texts, there is not really any substance other than that.
I don't think we have to go that far back. Plate tectonics, submersion and weathering does a good enough job of wiping the slate clean off the surface of the Earth, that any evidence of earlier hominids developing pre-industrial, coastal civilizations say, a million years ago, would be now under the crust. What we consider civilization is about 5000 years old, so it's not inconceivable that the cycle might have occurred multiple times during geologic time spans. Perhaps this is the first time civilization was not interrupted and made its way through to a technological civilization.
I mean sure, if they somehow didn't have any trade goods that went in land, didn't work with metals enough to do any appreciable mining, and didn't breed any plants or animals enough to change their genetics. Any hypothetical hidden past civilization would have to have been weird in a number of ways to not leave any evidence.
We have plenty of fossil evidence from, from your example, a million year old hominids. Far more than we would need to expect to see evidence of civilization.
Subduction makes up for a tiny tiny proportion of where coastal land "goes" in any age.
You'd need an enormous set of coincidences for a past civilization of hominids to go unnoticed.
There's a seam of volcanic mountains that runs down the center of the Atlantic, but nothing that resembles a supervolcano. The supervolcano complex under the Pacific is one of the largest known in the solar system, however.
I think the article greatly underestimates our archaeological capabilities. We can identify five mass extinctions in the last 500 million years, so why should such a civilization simply be overlooked? Of course, we wouldn't find abandoned ruins, but the idea that an industrial civilization wouldn't leave behind any detectable artifacts is practically impossible. Perhaps there were a few primate species before that could make fire and hunt with bows and arrows, but certainly nothing industrial and hardly any extensive agricultural culture.
> I think the article greatly underestimates our archaeological capabilities.
"they found a single forerunner to their idea of deep time. It came not from science, but from science fiction. At this level of conjecture, there’s little difference. It was an episode of Dr. Who" also betrays an ignorance of the trope originator.[0]
I have a toy hypothesis that once civilization level intelligent life emerges it never disappears barring the planet it inhabits being vaporized by some unfortunately directed GRB or some similar catastrophe.
Our knowledge is becoming holographic such that to prevent the reemergence of civilization one would have to wipe out all of us at once.
depends how you define civilization level life.if you mean we cant be bumped back to hunter gatherers without wiping out almost all of us, you are probably correct. If you mean we will always have computers and the ability to split the atom, i dont agree. Knowledge and industry is way more fragile and we have loat working knowledge of simpler processes in favor of more advanced ones so it wont be that easy rebuilding through the lower rungs of the tech tree.
So there could have been this hypothetical civilization 55 million years ago already. And they've only just disappeared (if they did) 10'000 or so years ago? Without a trace?
Also, no, a conspiracy cannot be the answer to a question we've not yet asked. The word has a clear meaning, it requires people to conspire to hide something from you.
"Ancient mystical texts hint at earlier creation, the life that preceded the Garden, prequels to Genesis. These incarnations are not reported in the Bible because they are none of your goddamn business, but the evidence is everywhere. Some students of conspiracy believe there was a time when lizard people shared the earth with modern men, the older race dying as the younger emerged from the forest. The last of the lizards were worshipped as gods; these were the deities of ancient India and Greece. The technology—weapons and machines—created miracles. You can see the lizard kings in carvings from Mesopotamia, the oldest historical records, where humans bow before reptile men. You find them again in the Torah, where they appear as Nephilim..."
Yeah, the author is contradicting himself here: On the one hand, that civilization must have ended several million years ago, so erosion and plate tectonics had time to erase all traces - but on the other hand, humans were still having lively exchanges with those guys and viewing them as a normal part of their world in 10.000 BC...
We’ve already got fossils of dolphins. Not exactly the species we know today but close enough. We have enough fossils to trace their evolution since their ancestors walked on land. So yes, we definitely would have evidence that dolphins were here.
right, so how can one easily say this hypothesis is false? "advanced civilization" seems to be strangely characterized. would something a few steps above beavers be advanced enough?
>The oldest place on the earth’s surface—a stretch of Israel’s Negev Desert
I do not understand this statement, I thought an area in Quebec was around 3 - 4 billion years old. I looked, seems Australia may have the oldest area:
But I say the article could be true, but the only issue I have is the large dinos. I would think they could be an impediment to any organized settlements.
One other thing, didn't most of our fossil fuels come from the Carboniferous era ?
The claim isn't about the age of rock, but that the surface has churned almost everywhere. Israel does contain the oldest measured continuous surface at about 1.8M yo, but nobody claims to have looked everywhere.
How churned is "churned"? Does this mean particular pebbles have have been found to have lain in their current arrangement for 1.8 million years, or just that not much has happened? I expect any arid region far from the poles or mountains and lacking dune fields will have similar patches of inert land. Much of Australia would fit this bill.
So we have microbial fossils from 3.5 billion years ago, fossilised 300 million year old skin, bones from almost 200 my ago, even actually soft tissue inside a fossilised bone from 70 my ago. Ah, footprints too, the most unsubstantial matter of all: pure shape. That's in addition to all the million other fossils that are so common we hardly care: shells, small bones, etc.
And someone is saying there could have been an entire advanced civilization 400 million years ago, large and powerful enough to cause climate change, and that no traces of it would possibly be left? Like, billions of individuals, cities, factories, metals, concrete, mines, wells, roads and bridges and tunnels, stone sculptures!, plastic, waste dumps, farms, agricultural land, billions and billions of artifacts of all materials, most of them entirely artificial. All gone because "nothing resists 400 my" and, "oh btw, check this dinosaur footprint and this fossilised piece of skin, how cool"?
The counter argument: dinosaurs were around for a staggering amount of time, no pun intended. 165 million years is reasonably long enough to ensure they left behind some nests, bones, and a feather or two. Modern humans have been around for more like 0.02 million years.
The counter-counter argument is that while we’ve been here for a comparative blink of an eye, we’ve left behind 4 orders of magnitude more stuff than just nests, bones, and a feather or two.
Yea, but if humans went extinct tomorrow, very little human artifacts would remain after millions of years. Indeed, most would be gone well before that. How much stuff from the 18th century still remains, in percentage terms?
Unless it was burned, melted, decomposed or crushed to dust, it's all out there or in a landfill somewhere.
I do find it difficult to believe that we would not leave enough fossil and mineral evidence for future paleontologists to find. I get that the surface will churn, but layers of rock routinely become exposed, revealing the geological history of the area. No tea cup shards, no impressions of rusted cars in the mud, no concentration of metal in strangely rectilinear formations that suggests skyscrapers?
There would still be many signs. Dug up mines, metal alloys that don't exist in nature along with refined metals in quantities they don't exist, animal and plant species we bred along with all the ones we made extinct.
Very few things would in fact remain, you’re correct. But we’ve also created radioactive elements with half lives of many millions of years.
While there would probably very little direct evidence of humans after millions of years, there would probably be at least some anomalous evidence someone could find.
Indeed. Did a rapid check on T-rex, just as an example.
Was around for max 3.6 million years. Max population at any one time must have been around 20k individuals. We have about 150 skeletons.
So current human population is 400 thousand times the maximum T-rex population at any one time. A few decades are enough to produce more human individuals than the entire T-rexes history. We also have the ability to go (and die) pretty much anywhere, so there will be human skeletons in every crevice, depth and environment on Earth. We also produce an absolutely staggering amount of artifacts of all kinds, from plastic straws to giant tunnels and artificial caves. There are zero chances an advanced civilisation on Earth won't be aware of us in 400 million years.
Actually correct. We have very very few fossils compared to the millions of species that have evolved and gone extinct over 4 billion years.
The fossils we do have are of highly successful species in that geography. It’s a matter of chance, leaving behind a fossil, after all.
And unlike biological matter that can fossilize, industrial structures etc do not. All our manufactured stuff has very short life once it reaches the crust and starts getting compacted.
The more time you add, the better the odds we’d find this evidence lost.
And if this wasn’t a global, but more localized pre-human civilization, the evidence would be thinner still.
Which is why this isn’t a scientific hypothesis really. It’s more showing you the limits of scientific inquiry into the deep history of Earth.
> It’s more showing you the limits of scientific inquiry into the deep history of Earth.
I think this is it: the point of this argument is to inspire some awe in the listener, making them realise how vast Earth's time is compared to our horizons.
But in practice, the argument is wrong. A dead animal's skin is expected to lasts weeks to months- and yet we have fossilised specimens. A footprint typically lasts hours, and yet we have ones that are hundreds of millions of years old. Even if the expected lifespan of our artifacts is nothing in comparison with these timespans, a small percentage of artifacts will either be preserved or leave recognisable traces- exactly as it happened for soft tissues and footprints. It's extremely naive to think that none of this will leave traces.
> And someone is saying there could have been an entire advanced civilization 400 million years ago, large and powerful enough to cause climate change, and that no traces of it would possibly be left?
If humanity vanished today, in 1 million years almost all of our artifacts would be gone or burned under miles of subduction.
In 10 million years there would literally be nothing left.
> If humanity vanished today, in 1 million years almost all of our artifacts would be gone or burned under miles of subduction.
That is completely incorrect. We have sedimentary rocks from 100 M years ago on the Earth’s surface right now, that never underwent any kind of subduction.
Subduction only occurs at plate boundaries and is not nearly this fast. Continental plates float on top like foam and do not get subducted. It's the oceanic plate that is created at mid-ocean ridges and gets subducted at the margins.
To recognize the possibility, one has to grapple with incredible scale and deep time: In roughly 300 million years (1/10th of the time life has been around), the Appalachians split off from the Atlas; the Atlantic Ocean first started splitting open; uplifts underneath North America pushing the West up from the seabed and caused the rivers to carve millions of acres of sandstone landscape down, leaving towering plateaus, cliffs, and eventually river chasms. Over the 3 billion years before that, what was carried away like so much sediment? What was subsumed by subduction boundaries?
On a much more recent timescale, one of the dominant theories of the emergence of civilization places the ancestors of the Sumerians in a stupendously fertile valley at the bottom of what is now the Persian Gulf, eventually flooded during the retreat of the glacial maximum and covered in Tigris & Euphrates sediment. It could be the very origin of regional flood and primordial garden myths. But it's all buried.
This is a good thought experiment to show how time is as vast as space.
400 million years ago is as distant as the stars. The Earth was a different planet then, in a sense.
It’s also yet another Fermi paradox answer. Even if our civilization lasts for millions of years, that’s a blip. We are searching both space and time and both are incomprehensibly vast.
How can a galaxy spanning civilisation fail. If life can spread to other worlds, unless you get FTL, how could you end all life in a galaxy
As such it seems impossible for life to have reached interstellar travel anywhere in the Milky Way before at most a few million years ago, otherwise we would see it.
Which is weird because life surely can’t be that rare in the entirety of space time.
Of course the galaxy could be teaming with non interstellar life, but once you reach mankind’s level of sentience and technology it dormant seem a massive jump to interstellar, and once that happens there’s no way to put the genie back in the bottle.
Though there is likely life throughout the galaxy, it's probably difficult for one sentient spacefaring race to find another habitable planet they'd be comfortable on, i.e., one with a similar atmosphere and mass. If it's a long way from your planet to another you'd care to set foot on, you're left with lots of space stations. But who wants to live in that precarity?
I’d also say that we do not know for certain that no dinosaurs, such as raptors perhaps, were intelligent enough for language and culture.
At that age we can be pretty sure they did not have industry but they could have been like tribal hunter gatherers. If they did not build a lot and at large scale we’d have basically zero chance of finding anything. Stone, wood, animal skins, pottery, arrow heads, tools, etc., all that would be long gone. Metal would too but it might leave diagnostic traces, as would synthetic chemistry (plastics) or large scale fuel use.
Birds, the modern still living closest relatives of dinosaurs, are often strikingly intelligent especially relative to their brain mass. Dinosaurs had small brains relative to body size but while there is a correlation there with intelligence it’s not perfect. There’s exceptions, animals with small relative brain sizes that seem very smart, like elephants.
Time Machine movie reboot did this in opposite direction into future decently well
dude wind hundreds of thousands of years into future, sands of time, etc. modulo two warring biological descendants of humans not full diff species tho
Interesting topic, but (to immediately veer off of it) I really wish he would find another word and stop misusing "conspiracy." The word has already been through hell.
The fact there is still coal(and oil) in the ground pretty much rules out any "advanced" industrialized civilization that came before us.
I also use the Carboniferous Period as a metric as to why "Advanced alien life" isn't more abundant (and I believe it should be factored into the Fermi equation)...
All those trees growing, soaking up sun, dying and just laying there to be compressed and buried without anything to decompose them, and then humans using them like solar batteries to power civilization (i.e. burning the coal), is one of those million-to-one things that enabled the human race to develop beyond basic society.
We needed all that coal and oil (and gas) based power to get to the point - industrially and technologically - where we could even build solar panels or nuclear to replace them, so its not like you could start from first principals and jump straight to modern power generation either.
The odds that the same sequence of events - fungus and bacteria not having the tools to decompose lignin (or whatever the alien equivalent is) - to happen on an extra-solar planet is ... pardon my pun ... astronomical :D
(yes, I used a dash to separate ideas in a sentence, deal with it...)
Petroleum could be the byproduct of a previous civilization.
Also, just as we "engineered" animals and plants through selective breeding, previous animals/plants could have been the results of selective breeding by a previous civilization: There'd be no way to tell just as there'd be no way to tell our "tampering" a few million years in the future.
> Petroleum could be the byproduct of a previous civilization.
How so? We know how it forms, there is no real gap in understanding there. What could lead to the kind of distribution of oil and gas fields we can observe?
but again, would someone a million in the future be able to tell that today's bananas, corn, watermelons, cattle, dogs etc. were the result of selective breeding by an intelligent species? (with no human records for reference)
If they’re a bit observant they will see that a humongous number of animals of the same species shows up suddenly, and localised in big numbers. Besides, there are a lot of signs of human activities. We changed the atmosphere in ways that are likely to show up in sediments. We mined all the minerals we could find to turn them into widgets that are not going to disappear. Our plastic items will end up in sediments all over the place, with wrong isotopic signatures. We find them in all places where we can look, down to the bottom of the Mariana Trench. They are carried to the seas by the same rivers that leave the silt that turns into rocks. Beyond that, we are leaving entire strata of plastics and metals in landfills. A lot of the satellites we put up there will fall back to Earth, but not all of them will. Some have orbits that won’t decay in millions years. There is not a single aspect of the planet that we haven’t touched.
> would someone a million in the future be able to tell that today's bananas, corn, watermelons, cattle, dogs etc. were the result of selective breeding by an intelligent species?
They might be able to, based on when these disappeared, by comparing them to something more durable that is easier to date definitevely.
All those organic things bred to fulfill the purpose of being useful to our civilization would very quickly disappear and become outcompeted by the undomesticated species. This sudden disappearance (along with the disappearance of more durable artefacts, like steel/plastics) might hint to someone that these species "are not like the others".
Also by tying them to the cutoff in human remains (this is assuming humans disappear along with advanced civilization)
Silurian Hypothesis, SETI, a widely help motivation for space exploration, much of sci-fi: all posit a high-ish rate of life (or intelligent life) invention, because the alternative is terrifying. I/we need/enjoy this, but it's fiction. When humans reason about the rate, they're extremely biased by what they want to be true.
From author and druid John Michael Greer's essay, "The Next Ten Billion Years"[1],
"One hundred million years from now:
The universe has a surprise in store for the corvins, though. Their first moon landing included among its goals the investigation of some odd surface features, too small to be seen clearly by Earth-based equipment. That first lander thus set down on a flat lunar plain that, a very long time ago, was called the Sea of Tranquillity, and so it was that the stunned corvin astronauts found themselves facing the unmistakable remains of a spacecraft that arrived on the moon in the unimaginably distant past.
A few equivocal traces buried in terrestrial sediments had suggested already to corvin loremasters that another intelligent species might have lived on the Earth before them, though the theory was dismissed by most as wild speculation. The scattered remnants on the Moon confirmed them, and made it hard for even the most optimistic corvins to embrace the notion that some providence guaranteed the survival of intelligent species. The curious markings on some of the remains, which some loremasters suggested might be a mode of visual communication, resisted all attempts at decipherment, and very little was ever learnt for certain about the enigmatic ancient species that left its mark on the Moon."
1. https://www.resilience.org/stories/2013-09-05/the-next-ten-b...
What an amazing read! (and only slightly depressing)
Though I'm kind of disappointed the last section did not end with fusion power, stellar migration and artificial intelligence...
I can't speak to dinosaur people, but the population genetics of our own DNA reveals that there were never many humans on the planet till recently, so that rules out any very large human civilization. (Unless they genetically altered themselves to hide the evidence! Ahaaa...)
If whole populations were wiped out and the world was repopulated by a small remnant would that not account for it? Or if an extinct human species had an advanced civilisation?
The founder effect differs between small populations filtered from a large population vs a smaller parent population.
I want to point out that the silurian hypothesis is specifically about civilizations removed from us by geologic time. Advanced human precursor civilizations are much more effectively ruled out by the current evidence. Basically, a hypothetical precursor society either has to look very different from any we know about and materialize out of nowhere like alien colonists, or they didn't exist.
For example, we know they weren't using large amounts of fire because nothing in the global charcoal records points to that. We know they weren't using plants that produce pollen because we don't find phytoliths with domestication indicators. We know they weren't using surface metals, because there was lots of that still around when the classically ancient civilizations started. We know they didn't contribute significantly to the gene pool. We have no material culture from them. We don't have a location on Earth they would have lived in. Etc.
My thoughts:
Civilisation implies large scale agriculture.
Large scale agriculture implies specific pollen signatures.
We don't see any of these signatures in the pollen records dredged up from lakes and seas.
There was no previous civilisation in the last 1.4m years (this is the depth of the pollen records we have I think).
Or it stayed concentrated for a long time until local conditions forced a scattering.
No. That’s exactly how we know.
Isaac Asimov's Nightfall [0], but on a longer cycle?
Jokes aside, what is the evidence, beyond "Ancient mystical texts"?
[0] http://www.myths.com/pub/fiction/science-fiction/Asimov/Nigh...
I think there is no evidence for it, but I think the point of the Silurain hypothesis (which the article does not convey well) is that if there were such civilisations we would not know as its unlikely we would find any evidence.
So it not a falsifiable statement from the onset?
https://en.wikipedia.org/wiki/Falsifiability
This article is a weird mash-up of an actually very interesting paper [0] with random personal slop like i've asked my rabbi, consulted my kabbalah-initiated friends and for the fun mixed it up with some fashionable ancient text (Mahabharatha)
So maybe just stick right to the paper itself and its clearly stated motivation?
> Perhaps unusually, the authors of this paper are not convinced of the correctness of their proposed hypothesis. Were it to be true it would have profound implications and not just for astrobiology. However, most readers do not need to be told that it is always a bad idea to decide on the truth or falsity of an idea based on the consequences of it being true. While we strongly doubt that any previous industrial civilization existed before our own, asking the question in a formal way that articulates explicitly what evidence for such a civilization might look like raises its own useful questions related both to astrobiology and to Anthropocene studies. Thus, we hope that this paper will serve as motivation to improve the constraints on the hypothesis so that in future we may be better placed to answer our title question.
[0]https://www.cambridge.org/core/journals/international-journa...
However, since we do have plenty of fossils from Silurian, it is hard to believe that none of the advanced technologies never left any hint. Any idea?
Yes. We'd find mines, where the richest veins were mined out and what's left is spread in a pattern that clearly appears to be "a rich deposit but with the best stuff taken already". The mine itself would have long collapsed but would also leave interesting evidence, a pattern of mismatched geological layers that rather than looking like an earthquake or a tectonic upheaval would be something that is relatively clearly shaft-shaped and if followed into the mountain would open out into a pattern that indicates intelligent mining activity as the anomaly is further charted.
Places where there is suddenly a vast collection of foreign rocks from the other side of the world that can't be explained by glaciers.
Radioactivity from nuclear tests that can't be explained by stellar phenomena and leave a layer of weird isotopes and isotope ratios all around the world, as we already have done.
And while we aren't to the point we'd have found this quite yet necessarily, evidence on the Moon where unlike Earth evidence probably would in fact persist for millions of years, especially if it ever attained any scale, e.g., "a large complex of cities" might still leave a visible mark on the surface easily visible to modern satellites and clearly with no other explanation available as to what caused it.
People get stuck on the idea that the only way to determine there was intelligent life earlier is to find a super complicated artifact which obviously can't survive, but there are footprints we've left in the world that are way, way larger than a cell phone or even a major city.
I don't find it hard to believe we've lost entire human civilizations. In fact I'd call it the smart bet. Maybe those civilizations were even a bit more sophisticated than we'd have thought, with maybe an earlier and entirely unknown Iron Age popping up somewhere for some period of time or something. But this is the first major technological civilization this planet has ever seen, even across geological time scales. And those lost human civilizations never reached to the level where they took all the easy resources like we have, because if they had, we wouldn't be able to get them. Some resources we call "non-renewable" do replenish on a few million year time scale, but we also pull lots of resources out of billion-year-old rocks, such as copper mines in northern Michigan which are pulling resources out of pre-Cambrian rocks. Clearly nobody else has been there, at scale.
The exception that proves the rule is a nuclear reactor from Gabon that dates to 1.7bn years ago... and which was clearly natural, a uranium-rich cave got flooded and went supercritical: https://en.wikipedia.org/wiki/Oklo
Of course we haven't discovered everything. But it seems very likely that if there were a civilization's worth of slag from 500m years ago, we would have discovered it.
A more interesting question is the civilizational technology of domestication, especially since that is short-term technology coupled with long-term evolution. It does seem possible (but purely fantastical) that Earth had talking dinosaurs with sophisticated ideologies and mythologies, feeding dumber dinosaurs and curating the growth of nutritious plants, the descendants of which all died 65m years ago.
> People get stuck on the idea that the only way to determine there was intelligent life earlier is to find a super complicated artifact which obviously can't survive
Why is it obvious that none of them can survive? Ordinary bones can become rocks (fossils) that are preserved. If mining of iron ore is visible, things would have been made out of iron -- wouldn't a large structure made out of iron leave some trace? Or even a small one? Why are there dinosaur fossils galore, but not so much as a pre-human fidget spinner to be found?
> Any idea?
Not really, because none of this passes the smell test if you know even a tiny bit about geology and paleontology. The most solid arguments are religious texts, there is not really any substance other than that.
I don't think we have to go that far back. Plate tectonics, submersion and weathering does a good enough job of wiping the slate clean off the surface of the Earth, that any evidence of earlier hominids developing pre-industrial, coastal civilizations say, a million years ago, would be now under the crust. What we consider civilization is about 5000 years old, so it's not inconceivable that the cycle might have occurred multiple times during geologic time spans. Perhaps this is the first time civilization was not interrupted and made its way through to a technological civilization.
I mean sure, if they somehow didn't have any trade goods that went in land, didn't work with metals enough to do any appreciable mining, and didn't breed any plants or animals enough to change their genetics. Any hypothetical hidden past civilization would have to have been weird in a number of ways to not leave any evidence.
>coastal civilizations say, a million years ago, would be now under the crust.
Nah, you way off on that, coastlines have remained relatively same last million years, def not subducted into an ocean trench
Huh?
We have plenty of fossil evidence from, from your example, a million year old hominids. Far more than we would need to expect to see evidence of civilization.
Subduction makes up for a tiny tiny proportion of where coastal land "goes" in any age.
You'd need an enormous set of coincidences for a past civilization of hominids to go unnoticed.
> or it could’ve been the eruption of a monster volcano, the sort that presently smolders beneath the Atlantic.
I know about Yellowstone, Campi Flegrei, etc, but I haven't heard about a supervolcano below the Atlantic. What's that referring to?
There's a seam of volcanic mountains that runs down the center of the Atlantic, but nothing that resembles a supervolcano. The supervolcano complex under the Pacific is one of the largest known in the solar system, however.
> There's a seam of volcanic mountains that runs down the center of the Atlantic
Yeah, that's the pacific rim, which in some sense is the opposite of a volcano.
Technical ceramics would have survived.
Reminds me of this comic: https://badspacecomics.com/scour-copy-copy
I think the article greatly underestimates our archaeological capabilities. We can identify five mass extinctions in the last 500 million years, so why should such a civilization simply be overlooked? Of course, we wouldn't find abandoned ruins, but the idea that an industrial civilization wouldn't leave behind any detectable artifacts is practically impossible. Perhaps there were a few primate species before that could make fire and hunt with bows and arrows, but certainly nothing industrial and hardly any extensive agricultural culture.
> I think the article greatly underestimates our archaeological capabilities.
"they found a single forerunner to their idea of deep time. It came not from science, but from science fiction. At this level of conjecture, there’s little difference. It was an episode of Dr. Who" also betrays an ignorance of the trope originator.[0]
[0] https://en.wikipedia.org/wiki/Serpent_Men
I have a toy hypothesis that once civilization level intelligent life emerges it never disappears barring the planet it inhabits being vaporized by some unfortunately directed GRB or some similar catastrophe.
Our knowledge is becoming holographic such that to prevent the reemergence of civilization one would have to wipe out all of us at once.
depends how you define civilization level life.if you mean we cant be bumped back to hunter gatherers without wiping out almost all of us, you are probably correct. If you mean we will always have computers and the ability to split the atom, i dont agree. Knowledge and industry is way more fragile and we have loat working knowledge of simpler processes in favor of more advanced ones so it wont be that easy rebuilding through the lower rungs of the tech tree.
The timelines don't really add up for me.
So there could have been this hypothetical civilization 55 million years ago already. And they've only just disappeared (if they did) 10'000 or so years ago? Without a trace?
Also, no, a conspiracy cannot be the answer to a question we've not yet asked. The word has a clear meaning, it requires people to conspire to hide something from you.
No. The idea is they could have lived and thrived for a few thousand years a few million years ago, then gone extinct.
That's not what the articles says though:
"Ancient mystical texts hint at earlier creation, the life that preceded the Garden, prequels to Genesis. These incarnations are not reported in the Bible because they are none of your goddamn business, but the evidence is everywhere. Some students of conspiracy believe there was a time when lizard people shared the earth with modern men, the older race dying as the younger emerged from the forest. The last of the lizards were worshipped as gods; these were the deities of ancient India and Greece. The technology—weapons and machines—created miracles. You can see the lizard kings in carvings from Mesopotamia, the oldest historical records, where humans bow before reptile men. You find them again in the Torah, where they appear as Nephilim..."
That’s not the Silurian hypothesis the astrophysicists put out. That’s the author extending it to fit those myths.
Yeah, the author is contradicting himself here: On the one hand, that civilization must have ended several million years ago, so erosion and plate tectonics had time to erase all traces - but on the other hand, humans were still having lively exchanges with those guys and viewing them as a normal part of their world in 10.000 BC...
Yeah sorry if I haven't made myself clearer, I was referring to the article.
if all dolphins were wiped out could we know that they were ever here from physical evidence?
We’ve already got fossils of dolphins. Not exactly the species we know today but close enough. We have enough fossils to trace their evolution since their ancestors walked on land. So yes, we definitely would have evidence that dolphins were here.
We’ll never know of the existence of most species that ever existed. Fossilization is rare.
right, so how can one easily say this hypothesis is false? "advanced civilization" seems to be strangely characterized. would something a few steps above beavers be advanced enough?
Dr Who and the Silurians had this covered: https://tardis.fandom.com/wiki/Silurian
That is explicitly referenced in the article.
>The oldest place on the earth’s surface—a stretch of Israel’s Negev Desert
I do not understand this statement, I thought an area in Quebec was around 3 - 4 billion years old. I looked, seems Australia may have the oldest area:
https://www.bbc.com/travel/article/20220126-is-the-pilbara-t...
But I say the article could be true, but the only issue I have is the large dinos. I would think they could be an impediment to any organized settlements.
One other thing, didn't most of our fossil fuels come from the Carboniferous era ?
https://en.wikipedia.org/wiki/Carboniferous
The claim isn't about the age of rock, but that the surface has churned almost everywhere. Israel does contain the oldest measured continuous surface at about 1.8M yo, but nobody claims to have looked everywhere.
How churned is "churned"? Does this mean particular pebbles have have been found to have lain in their current arrangement for 1.8 million years, or just that not much has happened? I expect any arid region far from the poles or mountains and lacking dune fields will have similar patches of inert land. Much of Australia would fit this bill.
So we have microbial fossils from 3.5 billion years ago, fossilised 300 million year old skin, bones from almost 200 my ago, even actually soft tissue inside a fossilised bone from 70 my ago. Ah, footprints too, the most unsubstantial matter of all: pure shape. That's in addition to all the million other fossils that are so common we hardly care: shells, small bones, etc.
And someone is saying there could have been an entire advanced civilization 400 million years ago, large and powerful enough to cause climate change, and that no traces of it would possibly be left? Like, billions of individuals, cities, factories, metals, concrete, mines, wells, roads and bridges and tunnels, stone sculptures!, plastic, waste dumps, farms, agricultural land, billions and billions of artifacts of all materials, most of them entirely artificial. All gone because "nothing resists 400 my" and, "oh btw, check this dinosaur footprint and this fossilised piece of skin, how cool"?
The counter argument: dinosaurs were around for a staggering amount of time, no pun intended. 165 million years is reasonably long enough to ensure they left behind some nests, bones, and a feather or two. Modern humans have been around for more like 0.02 million years.
The counter-counter argument is that while we’ve been here for a comparative blink of an eye, we’ve left behind 4 orders of magnitude more stuff than just nests, bones, and a feather or two.
Yea, but if humans went extinct tomorrow, very little human artifacts would remain after millions of years. Indeed, most would be gone well before that. How much stuff from the 18th century still remains, in percentage terms?
Unless it was burned, melted, decomposed or crushed to dust, it's all out there or in a landfill somewhere.
I do find it difficult to believe that we would not leave enough fossil and mineral evidence for future paleontologists to find. I get that the surface will churn, but layers of rock routinely become exposed, revealing the geological history of the area. No tea cup shards, no impressions of rusted cars in the mud, no concentration of metal in strangely rectilinear formations that suggests skyscrapers?
There would still be many signs. Dug up mines, metal alloys that don't exist in nature along with refined metals in quantities they don't exist, animal and plant species we bred along with all the ones we made extinct.
Very few things would in fact remain, you’re correct. But we’ve also created radioactive elements with half lives of many millions of years.
While there would probably very little direct evidence of humans after millions of years, there would probably be at least some anomalous evidence someone could find.
Indeed. Did a rapid check on T-rex, just as an example. Was around for max 3.6 million years. Max population at any one time must have been around 20k individuals. We have about 150 skeletons.
So current human population is 400 thousand times the maximum T-rex population at any one time. A few decades are enough to produce more human individuals than the entire T-rexes history. We also have the ability to go (and die) pretty much anywhere, so there will be human skeletons in every crevice, depth and environment on Earth. We also produce an absolutely staggering amount of artifacts of all kinds, from plastic straws to giant tunnels and artificial caves. There are zero chances an advanced civilisation on Earth won't be aware of us in 400 million years.
>We also produce an absolutely staggering amount of artifacts of all kinds, from plastic straws to giant tunnels and artificial caves.
Plastic will be gone in ~1000 years,
https://www.activesustainability.com/environment/waste-plane...
tunnels and artificial caves in a few million years at most as they are compressed by the weight of the rocks above them ("tunnel squeezing").
How long to dissolve carved stone sculptures (in sizes ranging from 1cm to 100m?)
And how long does it take to dissolve skin? Footprints? Because we have those from hundreds of millions of years ago.
Actually correct. We have very very few fossils compared to the millions of species that have evolved and gone extinct over 4 billion years.
The fossils we do have are of highly successful species in that geography. It’s a matter of chance, leaving behind a fossil, after all.
And unlike biological matter that can fossilize, industrial structures etc do not. All our manufactured stuff has very short life once it reaches the crust and starts getting compacted.
The more time you add, the better the odds we’d find this evidence lost.
And if this wasn’t a global, but more localized pre-human civilization, the evidence would be thinner still.
Which is why this isn’t a scientific hypothesis really. It’s more showing you the limits of scientific inquiry into the deep history of Earth.
> It’s more showing you the limits of scientific inquiry into the deep history of Earth.
I think this is it: the point of this argument is to inspire some awe in the listener, making them realise how vast Earth's time is compared to our horizons.
But in practice, the argument is wrong. A dead animal's skin is expected to lasts weeks to months- and yet we have fossilised specimens. A footprint typically lasts hours, and yet we have ones that are hundreds of millions of years old. Even if the expected lifespan of our artifacts is nothing in comparison with these timespans, a small percentage of artifacts will either be preserved or leave recognisable traces- exactly as it happened for soft tissues and footprints. It's extremely naive to think that none of this will leave traces.
> And someone is saying there could have been an entire advanced civilization 400 million years ago, large and powerful enough to cause climate change, and that no traces of it would possibly be left?
If humanity vanished today, in 1 million years almost all of our artifacts would be gone or burned under miles of subduction.
In 10 million years there would literally be nothing left.
> If humanity vanished today, in 1 million years almost all of our artifacts would be gone or burned under miles of subduction.
That is completely incorrect. We have sedimentary rocks from 100 M years ago on the Earth’s surface right now, that never underwent any kind of subduction.
Bollocks. We find fossils millions of years old right on the surface.
> under miles of subduction
Subduction only occurs at plate boundaries and is not nearly this fast. Continental plates float on top like foam and do not get subducted. It's the oceanic plate that is created at mid-ocean ridges and gets subducted at the margins.
To recognize the possibility, one has to grapple with incredible scale and deep time: In roughly 300 million years (1/10th of the time life has been around), the Appalachians split off from the Atlas; the Atlantic Ocean first started splitting open; uplifts underneath North America pushing the West up from the seabed and caused the rivers to carve millions of acres of sandstone landscape down, leaving towering plateaus, cliffs, and eventually river chasms. Over the 3 billion years before that, what was carried away like so much sediment? What was subsumed by subduction boundaries?
On a much more recent timescale, one of the dominant theories of the emergence of civilization places the ancestors of the Sumerians in a stupendously fertile valley at the bottom of what is now the Persian Gulf, eventually flooded during the retreat of the glacial maximum and covered in Tigris & Euphrates sediment. It could be the very origin of regional flood and primordial garden myths. But it's all buried.
This is a good thought experiment to show how time is as vast as space.
400 million years ago is as distant as the stars. The Earth was a different planet then, in a sense.
It’s also yet another Fermi paradox answer. Even if our civilization lasts for millions of years, that’s a blip. We are searching both space and time and both are incomprehensibly vast.
How can a galaxy spanning civilisation fail. If life can spread to other worlds, unless you get FTL, how could you end all life in a galaxy
As such it seems impossible for life to have reached interstellar travel anywhere in the Milky Way before at most a few million years ago, otherwise we would see it.
Which is weird because life surely can’t be that rare in the entirety of space time.
Of course the galaxy could be teaming with non interstellar life, but once you reach mankind’s level of sentience and technology it dormant seem a massive jump to interstellar, and once that happens there’s no way to put the genie back in the bottle.
Though there is likely life throughout the galaxy, it's probably difficult for one sentient spacefaring race to find another habitable planet they'd be comfortable on, i.e., one with a similar atmosphere and mass. If it's a long way from your planet to another you'd care to set foot on, you're left with lots of space stations. But who wants to live in that precarity?
> time is as vast as space.
This is what I always say to "Why haven't we found any aliens yet??"
Hell, we wouldn't even have known about the existence dinosaurs, lifeforms on THIS VERY PLANET, if we hadn't chanced upon their remains.
I’d also say that we do not know for certain that no dinosaurs, such as raptors perhaps, were intelligent enough for language and culture.
At that age we can be pretty sure they did not have industry but they could have been like tribal hunter gatherers. If they did not build a lot and at large scale we’d have basically zero chance of finding anything. Stone, wood, animal skins, pottery, arrow heads, tools, etc., all that would be long gone. Metal would too but it might leave diagnostic traces, as would synthetic chemistry (plastics) or large scale fuel use.
Birds, the modern still living closest relatives of dinosaurs, are often strikingly intelligent especially relative to their brain mass. Dinosaurs had small brains relative to body size but while there is a correlation there with intelligence it’s not perfect. There’s exceptions, animals with small relative brain sizes that seem very smart, like elephants.
I'm butt hurt that I'm five paragraphs in and still have no idea what the hypothesis is.
Time Machine movie reboot did this in opposite direction into future decently well
dude wind hundreds of thousands of years into future, sands of time, etc. modulo two warring biological descendants of humans not full diff species tho
Interesting topic, but (to immediately veer off of it) I really wish he would find another word and stop misusing "conspiracy." The word has already been through hell.
The fact there is still coal(and oil) in the ground pretty much rules out any "advanced" industrialized civilization that came before us.
I also use the Carboniferous Period as a metric as to why "Advanced alien life" isn't more abundant (and I believe it should be factored into the Fermi equation)...
All those trees growing, soaking up sun, dying and just laying there to be compressed and buried without anything to decompose them, and then humans using them like solar batteries to power civilization (i.e. burning the coal), is one of those million-to-one things that enabled the human race to develop beyond basic society.
We needed all that coal and oil (and gas) based power to get to the point - industrially and technologically - where we could even build solar panels or nuclear to replace them, so its not like you could start from first principals and jump straight to modern power generation either.
The odds that the same sequence of events - fungus and bacteria not having the tools to decompose lignin (or whatever the alien equivalent is) - to happen on an extra-solar planet is ... pardon my pun ... astronomical :D
(yes, I used a dash to separate ideas in a sentence, deal with it...)
Petroleum could be the byproduct of a previous civilization.
Also, just as we "engineered" animals and plants through selective breeding, previous animals/plants could have been the results of selective breeding by a previous civilization: There'd be no way to tell just as there'd be no way to tell our "tampering" a few million years in the future.
> Petroleum could be the byproduct of a previous civilization.
How so? We know how it forms, there is no real gap in understanding there. What could lead to the kind of distribution of oil and gas fields we can observe?
Just fun to think about and base fiction on
I mean, would an ant walking on a highway be able to tell that it's artificial?
Probably not, but an ant cannot do any kind of isotope analysis.
hah
but again, would someone a million in the future be able to tell that today's bananas, corn, watermelons, cattle, dogs etc. were the result of selective breeding by an intelligent species? (with no human records for reference)
If they’re a bit observant they will see that a humongous number of animals of the same species shows up suddenly, and localised in big numbers. Besides, there are a lot of signs of human activities. We changed the atmosphere in ways that are likely to show up in sediments. We mined all the minerals we could find to turn them into widgets that are not going to disappear. Our plastic items will end up in sediments all over the place, with wrong isotopic signatures. We find them in all places where we can look, down to the bottom of the Mariana Trench. They are carried to the seas by the same rivers that leave the silt that turns into rocks. Beyond that, we are leaving entire strata of plastics and metals in landfills. A lot of the satellites we put up there will fall back to Earth, but not all of them will. Some have orbits that won’t decay in millions years. There is not a single aspect of the planet that we haven’t touched.
> would someone a million in the future be able to tell that today's bananas, corn, watermelons, cattle, dogs etc. were the result of selective breeding by an intelligent species?
They might be able to, based on when these disappeared, by comparing them to something more durable that is easier to date definitevely.
All those organic things bred to fulfill the purpose of being useful to our civilization would very quickly disappear and become outcompeted by the undomesticated species. This sudden disappearance (along with the disappearance of more durable artefacts, like steel/plastics) might hint to someone that these species "are not like the others".
Also by tying them to the cutoff in human remains (this is assuming humans disappear along with advanced civilization)
Joe Rogan tier pseudoscience.
Silurian Hypothesis, SETI, a widely help motivation for space exploration, much of sci-fi: all posit a high-ish rate of life (or intelligent life) invention, because the alternative is terrifying. I/we need/enjoy this, but it's fiction. When humans reason about the rate, they're extremely biased by what they want to be true.