Civilizations Lost in Deep Time
April 22, 2019 2:06 PM   Subscribe

“Wait a second,” he said. “How do you know we’re the only time there’s been a civilization on our own planet?” [...] There are fossils, of course. But the fraction of life that gets fossilized is always minuscule and varies a lot depending on time and habitat. It would be easy, therefore, to miss an industrial civilization that only lasted 100,000 years—which would be 500 times longer than our industrial civilization has made it so far.
It’s not often that you write a paper proposing a hypothesis that you don’t support. Gavin and I don’t believe the Earth once hosted a 50-million-year-old Paleocene civilization. But by asking if we could “see” truly ancient industrial civilizations, we were forced to ask about the generic kinds of impacts any civilization might have on a planet. [...] Once you realize, through climate change, the need to find lower-impact energy sources, the less impact you will leave. So the more sustainable your civilization becomes, the smaller the signal you’ll leave for future generations.
Adam Frank and Gavin Schmidt discuss the Silurian Hypothesis: would it be possible to detect an industrial civilization in the geological record? (And what would that mean for our industrial civilization?)
posted by ragtag (103 comments total) 66 users marked this as a favorite
 
When I was in college, getting a geology degree, my friend and I used to postulate that dinosaurs had cars, we just hadn't found the evidence yet...
posted by Windopaene at 2:20 PM on April 22 [6 favorites]


For whatever reason, I feel a lot more existential angst about questions like this and whether there will be any trace of human civilization in the future, the sun blowing up, etc than I do about my own mortality. Glad I have a new one to keep me awake at night!
posted by Corduroy at 2:24 PM on April 22 [8 favorites]


Reminds me of the time travel sequence in The Time Machine. Especially the last few minutes of this video clip.
posted by darkstar at 2:27 PM on April 22 [2 favorites]


This is neat.

But, I don't understand the Suess effect argument. 14C has a half-life of 5000 years and decays into the most common isotope of nitrogen. I'd expect a bronze statute to last much longer than a 14C over-abundance. (Or is there some argument about 13C/12C ratios that I'm missing?)
posted by eotvos at 2:29 PM on April 22


When I was in college, getting a geology degree, my friend and I used to postulate that dinosaurs had cars, we just hadn't found the evidence yet...

Isn't this more or less the theory behind the TV show Dinosaurs?
posted by jmauro at 2:30 PM on April 22 [15 favorites]


i'll never tell
posted by Rhaomi at 2:31 PM on April 22 [9 favorites]


Wasn't there a huge site out there in the web 1.0 days meticulously crafting a silurian hypothesis?
posted by BungaDunga at 2:37 PM on April 22


(I say huge, I mean one of those big ol' webs of Geocities interlinked hypertext sites that got more and more batshit the deeper you looked)
posted by BungaDunga at 2:37 PM on April 22 [3 favorites]


The World Without Us takes a look at what bits of our civilization would endure, and how long, in the event of a sudden extinction event.
posted by BungaDunga at 2:41 PM on April 22 [13 favorites]


When I see a creature like Harley the Cockatoo, I don’t have any difficulty picturing a reasonably intelligent dinosaur - something smart enough to make simple tools and organized settlements.
posted by bonobothegreat at 2:42 PM on April 22 [7 favorites]


I think about this a lot
posted by OverlappingElvis at 2:46 PM on April 22 [7 favorites]


For me, there's something extremely comforting about the idea that we could potentially overlook the vast majority of intelligent species across time and space, because it means that non-detection doesn't entail that they're not out there. Deep time, dark forest, and the fact that sustainability and difficulty of detection go hand in hand.
posted by the antecedent of that pronoun at 2:46 PM on April 22 [15 favorites]


Excuse me but a 100, 000 year old industrial civilization ? That's a lot of open pit mines. This concept does not have merit.
posted by y2karl at 3:01 PM on April 22 [14 favorites]


Only if you assume you need pit mines and metals for industrialization - an industrial model based entirely on living things wouldn't require anything of the sort, and would be undetectable after ten thousand years or so.
posted by aspersioncast at 3:06 PM on April 22 [8 favorites]


At 100 million (or more) years, the differences become far harder to detect, but not impossible, and based on the complete lack of information based on the tests the paper lays out, the likelihood is incredibly small.

As for the possibility that there was PRE-industrial intelligent life on Earth at some point in the deep past... there's no way to know. I'd consider it unlikely as well, but that's just back to Drake Equation territory. What are the chances? Not much, but not zero.
posted by tclark at 3:09 PM on April 22 [1 favorite]


A bit of theorizing about past industrial civilizations lays the groundwork for the Asimov short story Nightfall.
posted by duffell at 3:11 PM on April 22 [7 favorites]


The Amazonian rain forest was hugely populated with incredibly complex cities and technology. We’re only seeing it now through the unfortunate deforestation which shows the straightaways that were levees/roads between city states.

1491 and Lost City of Z go on in some detail about the extent of advanced civilizations that were lost because they didn’t build in metal and also because of how quickly jungle eats anything at all.

I have no doubt there’s a ton of shit we don’t know.
posted by sio42 at 3:12 PM on April 22 [33 favorites]


Ignoring how much earth we move around and process to get oil, if there were cycles of energy usage that made use of fossil fuels on the scale that we use them today, one would expect extraction and redistribution of various elements to occur in a way that suggested non-geological processes put them there — especially platinum-group and other rare elements used in chemical catalysis.
posted by They sucked his brains out! at 3:21 PM on April 22 [1 favorite]


That's a lot of open pit mines. This concept does not have merit.

The Great Lakes as Copper mines. hmmmm.
posted by 922257033c4a0f3cecdbd819a46d626999d1af4a at 3:27 PM on April 22 [9 favorites]


First take: this sounds like something no one asked a paleontologist or geologist about.

Article: "In my work as an astrophysicist, I’d begun researching global warming from an 'astrobiological perspective.'"

Second take: first take checks out.

Snark aside, the paper does seem interesting and reasonably argued. But I'd definitely be more interested in the opinion of someone with subject-area expertise.
posted by biogeo at 3:34 PM on April 22 [10 favorites]


Only if you assume you need pit mines and metals for industrialization - an industrial model based entirely on living things wouldn't require anything of the sort, and would be undetectable after ten thousand years or so.

A.K.A. "the Flintstones hypothesis."
posted by biogeo at 3:36 PM on April 22 [12 favorites]


A.K.A. "the Flintstones hypothesis."

Definitely, 100% the title of an unfinished Michael Crichton novel
posted by clockzero at 3:38 PM on April 22 [13 favorites]


That's a lot of open pit mines. This concept does not have merit.

Even assuming such mines were a requirement, tectonic activity or simple erosion could totally obliterate a mine on the time scales we're talking about, or at least render them indistinguishable from natural features of the landscape. Plus - I mean, it was only in 1990 that they identified the impact crater that took out the dinosaurs, and that was a good bit bigger than a mine.
posted by showbiz_liz at 3:46 PM on April 22 [10 favorites]


I keep thinking about this bit:

Civilization building means harvesting energy from the planet to do work.

I'm not up on the academic definition of civilization, so perhaps I'm wrong, but I'm not sure this is a safe assumption to make. Or, at least, I'm not sure it's necessarily any more true for 'civilizations' than it is for any other group of animals. When does a group of humans become a civilization? Is it truly impossible that humans (or any other animals) might have been able to develop one without fuel?
posted by showbiz_liz at 3:50 PM on April 22 [1 favorite]


Well obvs there was an iridium-based civilization that destroyed the dinosaurs.
posted by clawsoon at 4:01 PM on April 22 [18 favorites]


Civilization building means harvesting energy from the planet to do work.

I'm not up on the academic definition of civilization, so perhaps I'm wrong, but I'm not sure this is a safe assumption to make.


There really isn't one that's agreed on cross-disciplinarily. People studying different aspects of the material and social world characterize it in terms that suit their research agenda and empirical focus, I think. Frank and Schmidt's paper cited above is from a journal on astrophysics, for example, so they're probably thinking of civilization in distinctly materialist/technological terms.

Or, at least, I'm not sure it's necessarily any more true for 'civilizations' than it is for any other group of animals. When does a group of humans become a civilization? Is it truly impossible that humans (or any other animals) might have been able to develop one without fuel?

Without fuel (i.e., energy), which in this usage would probably include things like calories, sapient creatures as we understand them wouldn't be able to transform their environment in ways that serve their needs and allow them to move beyond mere ecological subsistence toward the accumulation of knowledge and the potentiation of their native abilities, freed to some relative degree from material want.
posted by clockzero at 4:06 PM on April 22 [2 favorites]


"Industrial civilization" is the key phrase here, I think.
posted by clawsoon at 4:07 PM on April 22 [4 favorites]


It's hard to say if any evidence might be found. Even plastics and glass don't last that long when you're talking in mega-years.
posted by Marky at 4:08 PM on April 22


showbiz_liz: I mean, it was only in 1990 that they identified the impact crater that took out the dinosaurs, and that was a good bit bigger than a mine.

That "crater" was the open-pit iridium mine, obvs.
posted by clawsoon at 4:13 PM on April 22 [2 favorites]


I feel that if a precursor civilization was anything like ours, there would be lots more junk lying around, conspicuous consumption and obsession with status being the center of most human civilizations and all.

Then again, there might still be other civilizations on this planet that stay hidden and refuse human contact for that very reason.
posted by BYiro at 4:13 PM on April 22 [1 favorite]


There are a lot of low-impact ways in which a sapient species could develop a high culture and then disappear without lasting traces, especially if they lived in a humid climate.

For all we know, dolphins and/or whales have been sharing oral histories for millions of years. I'd like to think so.
posted by Countess Elena at 4:15 PM on April 22 [13 favorites]


The dinosaurs were pretty smart, but I'm not sure they were smart enough to figure out how to have an open pit mine in the Gulf of Mexico. Unless Howard Hughes was a time traveler . . . hmm.
posted by Bee'sWing at 4:21 PM on April 22


This is a good enough place to list Graham Hancock's books.
posted by zardoz at 4:22 PM on April 22


Bee'sWing: The dinosaurs were pretty smart, but I'm not sure they were smart enough to figure out how to have an open pit mine in the Gulf of Mexico.

Maybe parrots are the dumber descendants of the iridium miners. It doesn't take all that long in geologic time for a big brain to evolve, and most of that evolution could've happened among a small group which didn't leave much of a record.
posted by clawsoon at 4:31 PM on April 22 [1 favorite]


The Great Lakes as Copper mines. hmmmm.

So they took the copper and left the iron? Seems unlikely.
posted by Autumnheart at 4:31 PM on April 22


Autumnheart: So they took the copper and left the iron? Seems unlikely.

Maybe they were an electricity-based civilization that never figured out internal combustion.
posted by clawsoon at 4:35 PM on April 22 [3 favorites]


Well, and think about Roman ruins in a lot of Europe which are way underground but certainly weren't when they were built. And that's only 2000 years ago. Things could be buried so deep that we'd never find them, just because of the accrual of dust and dirt across millennia.
posted by hippybear at 4:41 PM on April 22 [4 favorites]


It's like our arrogance back during the cold war, where we were busy transmitting analog radio / tv signals everywhere, and assuming that because we couldn't detect such signals from space that we must be alone.

Fast forward 70 years and take a 5G transmitter sending 1Gbps worth of 4K HDR H265 encoded video, that's like 500 separate 4K video channels... even if they could build equipment to "read" the signal, it would be literal random noise to them. I mean, that's 1 billion bits per second - how would you even begin to record that using a punch card or write it down using pen and paper? And then how would you decode it?

And that's just 70 years! What about 600 years? 6000 years? 60 million? The more efficient we get, the closer to pure random noise our data and physical traces will look like. I mean, imagine a sci-fi future where we have teleportation like star trek - we wouldn't need roads or vehicles. We wouldn't even need houses, force fields could provide shelter and climate control. Hard to see evidence of that in the fossil layer? Go one step further, and everyone gets uploaded into the cloud.

We have a lower chance of even recognizing what intelligent life looks like than we think...
posted by xdvesper at 4:43 PM on April 22 [49 favorites]


"Industrial civilization" is the key phrase here, I think.

Yes, this was my thought. Industrial and civilization imply a scale of several magnitudes of order greater than an artisanal no animals were endangered by the construction of this sticks and twigs radio telescope civilization of living things. Even if they filled their open pits with the remains of these living things, there is this thing called the fossil record. In which, even the invention of pre-industrial agriculture left a record of climate change, if I recall correctly.
posted by y2karl at 4:44 PM on April 22


Big History
posted by mfoight at 4:48 PM on April 22 [1 favorite]


You want memory of your civilization to last, you go big or you go home.
posted by Huffy Puffy at 4:49 PM on April 22 [6 favorites]


> First take: this sounds like something no one asked a paleontologist or geologist about.

Hmm, not sure if you're actually disputing anything in the work itself. Their arguments are pretty reasonable once you wrap your head around the real, staggering extent of a billion years. It's hard to do it justice without lapsing into incoherence, like the description of how big space is in the Hitchhiker's Guide. With thousands of years, you get Roman ruins. With millions of years, you get fossils. But when you have hundreds of millions of years to work with, that's geological time.

> I keep thinking about this bit: Civilization building means harvesting energy from the planet to do work. I'm not up on the academic definition of civilization, so perhaps I'm wrong, but I'm not sure this is a safe assumption to make.

I think clockzero answered this above; I'll add that the key insight in the work is, I think, almost a tautology. The more sustainable a civilization is, the lower its impact on the environment (by definition), and the less trace it will leave per century of its existence, but the longer it will last.

That might imply that over long-enough timescales, every intelligent species that dominates its environment leaves only a similar geological imprint, regardless of how long it lasts? Or it might not mean anything of the sort, if we eventually go on to create a Galaxy-spanning civilization and preserve the Earth as a historical park and monument to our origins.

Take a look around at the job we're doing so far, and place your bets, I guess.
posted by RedOrGreen at 4:54 PM on April 22 [9 favorites]


Large areas of the northern hemisphere have been wiped clean by repeated glaciation, a city confined to one of those areas could be completely gone.
posted by 445supermag at 5:03 PM on April 22 [5 favorites]


If I remember my geology 101 right, the great lakes are a totally ephemeral result of the big block of ice that was piled up there 20 thousand years ago. They will be gone in a blink of an eye as soon as isostatic rebound pushes them up.
You really got to dump a trillion tons of plastic all around the world to make your civilization's presence known.
Or, you know, Howard Hughes deep sea iridium mining ships.
posted by Bee'sWing at 5:04 PM on April 22 [4 favorites]


Plop some literal and figurative shit on the moon and shoot more junk into outer space and you're covered for a while.
posted by achrise at 5:07 PM on April 22


Oh nos! All this civilization and all we have left is poop on the moon ?
posted by y2karl at 5:25 PM on April 22 [1 favorite]


Actually, we took ours home or so I should hope.
posted by y2karl at 5:26 PM on April 22


Like literally we had an FPP about us leaving shit on the moon not even that long ago.
posted by hippybear at 5:28 PM on April 22 [2 favorites]


Previously
posted by biogeo at 5:29 PM on April 22 [1 favorite]


Ok, I'm vaguely remembering some scifi series where the Silurians developed space flight and fled to the galactic core to form the galaxy's most advanced civilization, which humans eventually encounter (and fail to impress the dinosaurs at all). What the heck am I thinking of???
posted by 1adam12 at 5:36 PM on April 22




'Always Coming Home' by Le Guin is what I kinda think of: Artifacts of previous civilizations is mostly just random plastic crud washing ashore. (There's also an old computer database console in the story, but it's not a big deal).
posted by ovvl at 6:17 PM on April 22 [3 favorites]


I take comfort that some remnant of humanity might burn in the strange engines of beings heretofore unimagined, and perhaps form some part of their “climate change is a hoax” bumper stickers.
posted by rodlymight at 6:38 PM on April 22 [6 favorites]


Like literally we had an FPP about us leaving shit on the moon not even that long ago.

I had not seen that and now I have. Two thoughts:

1. How quintessentially American. Truly.
2. Well, if it wasn't before this, the Moon is most certainly green cheese now.
posted by y2karl at 6:41 PM on April 22 [1 favorite]


Engines of Light series by Ken MacLeod has this sort of.
As does a book or series by Barry Longyear.
posted by jclarkin at 6:44 PM on April 22


I thought "things that we've permanently launched from earth outlasting tectonic plate subduction" was pretty obvious so I commented too quickly to link the Apollo poop thread, but we've also discussed Voyager (link has its own Previously).

Humanity has left a lot of stuff on the moon and nearby planets. Earthbound it'll be the plastic layer in the geologic record that conclusively tips the future off that we were here. And/or the fingerprint of global nuclear war. Who know what else we'll come up with?
posted by achrise at 6:50 PM on April 22 [1 favorite]


Listen I'm not saying Dolphins definitely had an advanced society on land before moving to the sea, I'm just saying the requirements for living under water, "open mouth, eat fish" doesn't require the kind of brain power they are bringing to the table.
posted by Space Coyote at 7:03 PM on April 22 [12 favorites]


My money is on ruins under the Sahara. Or perhaps the finely ground dust of ruins mixed in with the sands of the Sahara.
posted by b1tr0t at 7:16 PM on April 22 [4 favorites]


We all know from reading Julian May's Saga of Pliocene Exile that there was an industrial civilization before us, it was just created by aliens. I haven't read the last book so I don't know why we haven't found any evidence of it; no spoilers please.
posted by goatdog at 7:22 PM on April 22 [3 favorites]


Go one step further, and everyone gets uploaded into the cloud.

You realize that's not a literal cloud, right? It takes actual, non-small-scale technology to implement what's euphemistically referred to as an ephemeral ubiquitous nebula.
posted by Greg_Ace at 8:21 PM on April 22 [1 favorite]


I feel a lot more existential angst about questions like this and whether there will be any trace of human civilization in the future, the sun blowing up, etc than I do about my own mortality.

I, on the other hand, take comfort in the fact that Humanity will wipe itself out long before it manages to wipe out all life on Earth, and as soon as we are gone the Earth will begin to heal the scars we leave behind. In 10,000 years you'll have to go out of your way to find signs we ever existed, and perhaps someday a new more worthy race will rise up to possess this world.
posted by Mr.Encyclopedia at 8:35 PM on April 22 [4 favorites]


showbiz_liz: I mean, it was only in 1990 that they identified the impact crater that took out the dinosaurs, and that was a good bit bigger than a mine.

Maybe the dinosaurs were actually collateral damage in a war between *two* advanced civilizations. Maybe the KT event was caused not by a naturally-occurring meteorite hitting Earth, but a meteorite or some other large body deliberately fired at Earth by a giant mass driver.
posted by e-man at 9:42 PM on April 22


This idea is also the basis of the Mass Effect videogame series, only on a galactic scale.
posted by Halloween Jack at 9:58 PM on April 22 [1 favorite]


the fun thing about theories like this is the way they make the eons contained within the words "millions" and "billions" of years actually feel as vast as they truly are.
posted by Reyturner at 10:24 PM on April 22 [1 favorite]


The thing about dinosaur fossils that gets glossed over is how LONG those bastards loped around the planet. Sure, we find fossils in lots of places but they roamed the earth for HUNDREDS OF MILLIONS OF YEARS. The stability of life, especially with the instability of the environment, is remarkable.

There's a common data point about how (I'm messing up exact dinos, but you get the idea) the time between the T. Rex and the Stegosaurus being alive was longer than from the Stegosaurus to now. There is a LOT of dead dinos piled up down there. We practically trip over their bones by how common and plentiful they are. We think there are a lot of people on earth, but imagine the trillions of huge ass dinosaurs stacking on top of one another for millions and millions of years. Just quick math: if there were a million T. Rexes on the planet at once but they persisted for 10 million years there would be 10 TRILLION T. Rex corpses stacked up on our planet. Sheer quantity is why we find anything.

And then we find out stuff like giant mushrooms existed for a long time before trees were a thing but we have found hardly any record of them because they were mushy. Our existence would be hard to spot even if you were looking for it a million years from now - maybe a satellite would still be in orbit somehow? A million years is an unthinkable length of time to comprehend, with evolution flying around everywhere, celestial bodies smacking into the planet, mega-volcanoes and earthquakes and so much more being expected and not just vague concepts.
posted by lubujackson at 10:41 PM on April 22 [10 favorites]


If there had been an advanced civilization we might expect to see resource depletion. But, consider, there seems to be a curious lack of dark matter in our own solar system-- is not the reasonable conclusion that a civilization of technologically advanced dinosaurs mined out all the dark matter in our solar system to power their (probably crystal-based) FTL spacehips?
posted by Pyry at 10:45 PM on April 22 [6 favorites]


God, this is one of those things I've had stuck in my head since I was a little kid.
posted by bongo_x at 3:25 AM on April 23 [2 favorites]


One thing I always figured was that there'll be space junk floating around for millions of years. Everything in low earth orbit is going to burn up, but the stuff in high orbit and geosynchronous should stay up, even if it's not working. That was always my thought against the silurians.

(If I'm wrong about the satellites, please tell me. It'd be disappointing, but I'd rather know than not.)
posted by Hactar at 3:59 AM on April 23


if there were cycles of energy usage that made use of fossil fuels on the scale that we use them today, one would expect extraction and redistribution of various elements to occur in a way that suggested non-geological processes put them there

Maybe parrots are the dumber descendants of the iridium miners

My God, it's been staring us in the face this whole time! Polly wants a cracker!
posted by condour75 at 4:38 AM on April 23 [3 favorites]


I don't think many orbits are stable over that kind of time period. Most high orbit satellites will be perturbed by the Moon enough to be flung outwards or inwards sometime over 10M years. Even the Moon itself will be 400kms farther away by then due to tidal effects.
posted by rhamphorhynchus at 5:12 AM on April 23 [1 favorite]


One thing I always figured was that there'll be space junk floating around for millions of years.

That assumes a "Silurian" civilization would create artificial orbital satellites. But more to the point, on a scale of hundreds of millions of years, there's nothing we've put up so far that's unlikely to either fall or escape.
posted by aspersioncast at 5:14 AM on April 23 [1 favorite]


You realize that's not a literal cloud, right?

ALL HAIL THE GLOW CLOUD
posted by tobascodagama at 5:25 AM on April 23 [3 favorites]


> If I'm wrong about the satellites, please tell me. It'd be disappointing, but I'd rather know than not.

This is tricky, the kind of problem where you're dealing with extremely weak forces and extremely long periods of time. As you say, low earth orbit has a short lifespan, but up at geosynchronous altitude the atmosphere will be very very close to zero. But not actually zero. There's other considerations like the pull of the moon, the sun and even Jupiter. Over long periods, any satellite should either reach a resonant orbit with the Earth-Moon system, crash into one of those bodies or be thrown out entirely. Anything put into a solar orbit would likely still be there, but undetectable. The fact that we don't have any other permanent moons around the earth suggests that there may be no long-term stable configuration for other satellites - i.e., over geologic time, we probably wouldn't expect a geosynchronous satellite to remain.

I strongly recommend what someone recommended above - The World Without Us, which has a basic premise of 'If humans disappeared right now, what would any future archaeologists be able to find out about us'. And the answer is, well, not much. Even the much cited plastic goes away if some bacteria evolves to eat plastic, and it's not beyond the realms of possibility that this could happen - there's similar organic materials such as shellac that already are consumed by bacteria. Erosion and deposition over geologic time would remove evidence of mining and suchlike as well.

Corvids (crows, ravens, etc) have shown remarkable intelligence and tool-use - to the point where it isn't unreasonable to suggest that dinosaurs could have achieved a previous civilisation comparable to our own.
posted by BigCalm at 5:47 AM on April 23 [4 favorites]


And then how would you decode it?

You wouldn't, necessarily. But you would detect the extra energy if you went looking for it and it existed. Much of radio astronomy relies on teasing out tiny bits of interesting noise in a sea of other noise that we aren't presently interested in.
posted by wierdo at 5:58 AM on April 23


You realize that's not a literal cloud, right? It takes actual, non-small-scale technology to implement what's euphemistically referred to as an ephemeral ubiquitous nebula.

Clare's Third Law: "Any sufficiently advanced technology is indistinguishable from magic."

Over the time scales we're talking about, assuming a technologically advanced civilization could last that long, there could be methods of storing and transmitting information that are unimaginable and unrecognizable to us in the same way a computer or a radio would seem like magic to our ancestors a mere 10,000 years ago. They could very well exist as "ephemeral ubiquitous nebula".
posted by Sangermaine at 6:16 AM on April 23


Why get hung up on industrial civilizations? There are lost human civilizations that had distinct languages, tools, governments, religions, legends, etc., but which never approached what we'd call "industrial." Would their traces be expected to last one million years?

In isolation, how could you distinguish a single human-made flint arrowhead from a non-human-made flint arrowhead?
posted by Western Infidels at 6:41 AM on April 23 [7 favorites]


> If there had been an advanced civilization we might expect to see resource depletion.

This is something I think I've read about before. Wish I could remember where. Maybe something like this is discussed in John McPhee's Encounters with the Archdruid?

Basically, we have already extracted a lot of the easily extractable mineral resources near the surface of our planet. It requires significant energy and technology to find and get more stuff (eg copper or iron ore, oil, etc) out of the ground, and further resources to process said stuff once you dig it out. If our civilization (and associated technology) is wiped out, it would be difficult-to-impossible for a new industrial civilization to rise from the ashes, simply because the material resources are no longer there. It's hard to have a Bronze Age if you can't get the copper and tin out of the ground to make the bronze.

Of course, all of that stuff we've used up is still there, so on the timescale of tens of millions of years or more it would all end up in the ground somehow. But would it be easily extractable and usable? Hard to say.

The energy situation for a future industrial civilization would be different, too. As I understand it from my ecologist wife, the fossil fuels in the ground now are from a time when there weren't any bacteria/fungi that could decompose lignin on a large scale. But these now exist, so there would be no new fossil fuels deposited. Hard to imagine a future civilization going directly from burning wood to building solar panels, isn't it?

Of course, I may be mistaking a failure of imagination for an insight into necessity, as the saying goes. But the basic principle is that technology doesn't arise spontaneously, it is built progressively from simpler technologies as we learn how to marshal more and more concentrated energy resources and use more and more advanced materials; if these resources aren't available, what are you going to do?
posted by number9dream at 7:01 AM on April 23 [3 favorites]


If you like The World Without Us, you may also enjoy Life After People.
posted by box at 7:08 AM on April 23 [1 favorite]


Fast forward 70 years and take a 5G transmitter sending 1Gbps worth of 4K HDR H265 encoded video, that's like 500 separate 4K video channels... even if they could build equipment to "read" the signal, it would be literal random noise to them. I mean, that's 1 billion bits per second - how would you even begin to record that using a punch card or write it down using pen and paper? And then how would you decode it?

What we have, therefore, is a 70-year block of time, encompassing the bulk of the 20th century, but winding down in the early-to mid-90s, when our civilization might be comprehensible to a non-human being merely by observing its radio wave output.

Imagine, now, a sapient homunculus of near-omnipotent power, trapped in a small receptacle, who cannot see outside his vessel, who cannot escape, but who can receive input if it comes from outside (vibrations if his vessel is touched, for example) and has unlimited power inside his very limited space. What would the characteristics of such a sapient creature be?

First of all: I imagine he would be lonely. And also: that he might well go insane. But he also might spend long centuries trying to gather knowledge based on the inputs that pass through the walls of his vessel.

Over the course of many centuries or millennia, he could very well build an apparatus that allows himself to receive radio transmissions. Unable to change the environment outside his vessel, but with unlimited power inside it, he might eventually figure out how to see through time itself, thereby enabling himself to see the radio transmissions and pop-cultural fixations of Homo sapiens civilization in the 20th century. He is trapped, but he can at least watch TV until he's released.

We should then expect such a creature, despite having phenomenal cosmic power, to ingratiate himself to any manumitter by a rapid deployment of references to the only human civilization he's been able to observe within his vessel. Even if the homunculus emerges in the tenth century, he might pepper his speech with references to Taxi Driver or Disney World or Groucho Marx.

If I were this creature's manumitter, living sometime in the pre-20th-century world, I would obviously be confused by the homunculus's apparent obsession with a time period I haven't lived through. However, so long as he held true to his word to help me in exchange for freeing him, I would have to admit: strange though his speech might be, I ain't never had a friend like him.
posted by Greg Nog at 7:14 AM on April 23 [20 favorites]


Speaking of John McPhee, at one point in his geological anthology Annals of the Former World he says if you take nothing else away from the book, remember that fossils from the ocean floor have been found on Mount Everest.

The lesson I took from that is that all traces of our civilization would be "quickly" lost in the churn of plate tectonics.
posted by whuppy at 7:19 AM on April 23 [2 favorites]


And then we find out stuff like giant mushrooms existed for a long time before trees were a thing but we have found hardly any record of them because they were mushy

Hm. This is the first time I've ever realized that the name mushroom was a sort-of descriptive quality of the mushroom, equivalent to 'mush'.
posted by The_Vegetables at 7:25 AM on April 23 [1 favorite]


Imagine, now, a sapient homunculus of near omnipotent power,

That's a new fantastic point of view!
posted by otherchaz at 7:50 AM on April 23 [2 favorites]


There are lost human civilizations that had distinct languages, tools, governments, religions, legends, etc., but which never approached what we'd call "industrial."

I think about this a lot. Just between the Lion-man of the Hohlenstein-Stadel and the Lauscaux paintings lie some 18,000 years, a period several times the length of the whole of literate civilization! It boggles my mind to imagine the generations upon generations of people of whose lives we'll never have more than the merest inklings.
posted by octobersurprise at 7:59 AM on April 23 [12 favorites]


It's hard to have a Bronze Age if you can't get the copper and tin out of the ground to make the bronze..

We've gathered most of the useful metals into our cities (and garbage dumps). Any future non-human civilization would be able to mine those sites for their metals.
posted by monotreme at 8:48 AM on April 23 [4 favorites]


Basically, we have already extracted a lot of the easily extractable mineral resources near the surface of our planet. It requires significant energy and technology to find and get more stuff (eg copper or iron ore, oil, etc) out of the ground, and further resources to process said stuff once you dig it out. If our civilization (and associated technology) is wiped out, it would be difficult-to-impossible for a new industrial civilization to rise from the ashes, simply because the material resources are no longer there. It's hard to have a Bronze Age if you can't get the copper and tin out of the ground to make the bronze.

In a million years, whatever is left alive on this rock will be mining our landfills for raw materials, since they'll have abundant mineral supplies left over from our wanton waste of everything. Those landfills will have had a million years of biology and geology happen to them, so they probably won't be identifiable as anything other than randomly-occurring pockets of dense natural resource concentration.

Now, the more interesting question: ten thousand years ago, why was the copper and iron concentrated in dense pockets near the surface for Bronze-Age-humans to find? Would we be able to tell, from looking at a depleted millenia-old strip mine, what exactly happened there a million years prior?
posted by Mayor West at 9:00 AM on April 23 [6 favorites]


Ok, I'm vaguely remembering some scifi series where the Silurians developed space flight and fled to the galactic core to form the galaxy's most advanced civilization, which humans eventually encounter (and fail to impress the dinosaurs at all). What the heck am I thinking of???

Well, that was sorta the plot of one of the Dr. McNinja storylines, only the dinosaurs got blasted to another planet by the blast from the comet that caused the K-T extinction.
posted by notsnot at 9:06 AM on April 23 [2 favorites]


Now, the more interesting question: ten thousand years ago, why was the copper and iron concentrated in dense pockets near the surface for Bronze-Age-humans to find? Would we be able to tell, from looking at a depleted millenia-old strip mine, what exactly happened there a million years prior?

I don’t know, but they were real dicks to move the tin so far away from where the copper was.

(The first bronze was made with arsenic. Arsenic!)
posted by Huffy Puffy at 9:08 AM on April 23 [4 favorites]


If "industrial civilization" means "uses iron metallurgy," we can be confident that there has never been one like ours.

Modern civilization would not be "industrial" as we understand the term were it not for hematite, the most common ore of iron. The formation of the biggest hematite beds was an "only once" event in Earth's history, occurring around the time photosynthesis became common and the Earth's atmosphere changed from anaerobic, reducing chemistry to aerobic, oxidizing chemistry. This caused the iron in the oceans to precipitate as insoluble oxides. There are richer ores than hematite, and early metallurgy used them, but the fact that our own civilization has practically exhausted them (and now depends on ores that would not have been worth bothering with 80 years ago) argues that no previous civilization that used iron in anything like the quantities we do ever existed.

Upthread there are suggestions that given sufficient time, metal artifacts would decompose back into ore form and be reconcentrated by plate tectonics. I am not a geologist but this strikes me as silly (actual geologists are welcome to instruct me otherwise). In any case, that's not what happened to form the ore deposits we've already mined out, which as noted were formed before there was such a thing as multicellular (or even eukaryotic) life.
posted by Aardvark Cheeselog at 9:56 AM on April 23 [3 favorites]


MetaFilter: Imagine a sapient homunculus of near-omnipotent power ... trapped.
posted by Western Infidels at 10:09 AM on April 23 [3 favorites]


We only scratched the surface of our planet. We don't know what lies miles beneath us and what may have existed.
posted by StemCellPower at 1:08 PM on April 23


BTW, the author of this piece, Adam Frank, is quoted in this NY Times piece on the Gaia Hypothesis by Ferris Jabr:

The Earth Is Just as Alive as You Are: Scientists once ridiculed the idea of a living planet. Not anymore.
posted by homunculus at 1:08 PM on April 23 [4 favorites]


*Sigh* humans have a whole planet to play with and they shit all over it while I'm sitting here trapped in this fucking receptacle waiting for some manumitter to free me. When I finally get out there's going to be a goddamn reckoning, that's for sure.
posted by homunculus at 1:08 PM on April 23 [12 favorites]


MetaFilter: Imagine a sapient homunculus of near-omnipotent power ... trapped.

In an itty-bitty living space, even.
posted by tobascodagama at 1:25 PM on April 23 [2 favorites]


In an itty-bitty living space, even.

... a goddamn reckoning...
posted by homunculus at 1:31 PM on April 23 [2 favorites]


In Futurama, Professor Farnsworth invents a Forwards Time Machine, capable of only going forward. He slips when pushing buttons and they go far into the future, and then they kept jumping huge leaps (in hopes of coming across a Backwards Time Machine). One of the stops is the year 252525, where the medieval age is repeated but knights ride ostriches. Later epochs show various wildly different civilizations as time goes on. With newer civilizations seemingly ignorant of the distant-past previous ones.

I've always thought that was pretty close to reality.
posted by numaner at 1:48 PM on April 23


You can’t be a-referencing the Futurama forward time machine montage without linking to the song.
posted by Huffy Puffy at 1:56 PM on April 23 [1 favorite]


If only the Altrusians/Silurians/Voth had had their own Long Now Foundation. A short-sighted lot, they were.
posted by homunculus at 4:33 PM on April 23


An industrial model based upon living things is one hell of a colorless green idea sleeping furiously.

Although it does give a whole new meaning to the phrase 'factory farm,' I suppose.
posted by y2karl at 1:17 PM on April 24 [1 favorite]


Adam Frank: Getting Climate Change Right: In Light Of The Stars
In light of the stars, meaning in light of what we've learned from the universe's many, many worlds (including our own), we can see that planetary climates are a kind of vast machine. They have their own rules based on physics and chemistry. Most importantly, we have seen enough now to understand the basics of how those rules work (including when a biosphere is present). We have, in other words, learned how to think like a planet.

From that vantage point, everything changes.

Of course we triggered climate change. We've been using planetary-scale amounts of energy to build and maintain this amazing planetary-scale project of civilization. Of course the Earth noticed. What else did you expect to happen? Imagine that aliens, with our knowledge of climate, landed on Earth in ancient Rome. They could have looked around and predicted: "Yeah, you guys are gonna trigger climate change in a few thousand years."

In fact, aliens make an important part of this story. Given what we now know about climate, we can see that any large-scale technological civilization developing on any planet would likely trigger its own version of climate change. What is an industrial civilization but a means for converting vast amounts of energy into useful work? The laws of climate literally demand that so much energy use has to transform into planetary feedbacks.

So, yeah, we're a wildly successful species that's built a wildly successful planetary civilization. That changed the climate. Duh. What else did we expect to happen?

But are we smart enough, and successful enough, to see this truth and deal with it effectively?
posted by homunculus at 2:36 PM on April 24




When I was in college, getting a geology degree, my friend and I used to postulate that dinosaurs had cars, we just hadn't found the evidence yet...--Windopaene

I heard about a professor at Berkeley who used to tell his students about small dinosaur civilizations where they built tools, weapons, and even towns. When he went far enough that the students started freaking out he'd tell them that while there is certainly no evidence of such a thing occurring, you can't really prove such a thing has never happened. The total amount of dinosaur bones we've collected throughout the world can fit in a few trucks. (Note, I'm not sure if this is true--this is just how I heard the story). We do the best in building up theory based on what evidence we have, but there are massive gaps in our knowledge.

I should be careful what I say or some creationist will say "See? Dinosaurs could have existed along with humans!", but the lack of any (non-avian) dinosaur bones less than 60 million years old makes such a conclusion pretty silly even with our incomplete knowledge.
posted by eye of newt at 11:58 PM on April 24 [1 favorite]


without linking to the song.

in my defense, the song kinda sucks after multiple listens
posted by numaner at 8:22 AM on April 25


Maybe the dinosaurs were actually collateral damage in a war between *two* advanced civilizations. Maybe the KT event was caused not by a naturally-occurring meteorite hitting Earth, but a meteorite or some other large body deliberately fired at Earth by a giant mass driver.

Maybe dinosaurs were advanced enough to have a technological need for iridium, but made a terrible and fatal miscalculation In the process of harvesting a passing meteor.
posted by They sucked his brains out! at 10:43 PM on May 8 [2 favorites]


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