Time Cleanses Everything?

May 28, 2009 7:47 PM

Let's say, 15 million years ago, some creature on Earth got a boost and started a civilization in the span of around 100,000 years, getting to a renaissance-level society - architecture, art, philosophy, basic science, but no titanium, steel girders, nuclear waste, etc. Would they have left any evidence that we could find, or would time destroy the proof before we got here?
posted by AzraelBrown to Science & Nature (36 answers total)

Best answer: Would they have left any evidence that we could find, or would time destroy the proof before we got here?

I think that answer largely depends on where the civilization was located. Areas prone to glaciation would, essentially, be wiped clean every ice age.
posted by nathan_teske at 7:58 PM on May 28, 2009

basic science? I think they were a bit past basic science in the renaissance era.

Anyhow YES there would be signs of this society due to size of population needed, sedentary lifestyle and artifacts. The need for agriculture would also be presumed due to a sedentary lifestyle.
posted by tarvuz at 8:00 PM on May 28, 2009

Best answer: Ceramics and faceted gemstones, maybe. Not much else.

Pity they weren't advanced enough to leave an old car and some bags of pee on the moon. Those might be findable under a heavy layer of dust.
posted by codswallop at 8:09 PM on May 28, 2009 [1 favorite]

We have fossils much older than that, for example, so this creature would probably appear in the fossil records somewhere, probably with a few artifacts. We have so little fossils that whole civilizations would fit in the spaces we don't know anything about, but it's doubtful. What we have may be spotty but it's pretty consistent.
posted by bru at 8:11 PM on May 28, 2009

Bronze or other metal sculpture might have a chance.
posted by 0xFCAF at 8:12 PM on May 28, 2009

What time has destroyed is somewhat hard to judge, as by definition what we see is what survived. Your question places this civilization geologically around the Miocene epoch; we have fossils from that time, of course, but most things are not fossilized.

Whether your hypothetical civilization would have left any signs depends a lot on their location and their culture. What materials is their architecture based on? What do they do with their dead?

If your question is taken as "If human civilization stopped in the renaissance, what signs would there be of it in 15 million years?" then there are some certainties to work from. Based on the population living in high numbers in varied climates, it's likely a good number of things and people would end up fossilized.
posted by Nomiconic at 8:13 PM on May 28, 2009

The History channel recently did a show called Life After People that went into the science of how long it would take evidence of our current civilization to be lost. The gist of it was that after 500 years, even the really big monuments like the Eiffel Tower would be gone. What "gone" means varies depending on the environment, but it amounted to not visible using a superficial glance. Basically, by that point most roads would be covered by plantlife and you'd have never known there was a road there, although obviously it would be there if you did some digging. Buildings and other things will have fallen down or been overtaken by nature.

There are exceptions to even that, though, in very dry climates. The pyramids are still around, for example. So to what degree it would be obvious that a civilization previously existed there would depend on the environment.

The other thing about the show, though, is that the building materials we use today are cheaper and tend not to be as long-lasting as some used in the past. So it would depend what they made their buildings out of, too.

There are a lot of factors, really. There would probably be fossils, but you'd have to know where to look. I think if you're interested in that sort of thing the Life After People show might give you some grounds for comparison and a better handle on the sorts of things that might still be around, and just how quickly a civilization can get swallowed up. I know it's available on torrent sites.
posted by Nattie at 8:27 PM on May 28, 2009 [1 favorite]

Rock outcroppings in Canada and elsewhere date to 4 billion years or so, so it's possible that in extremely stable regions much evidence would survive.

Much of this thought process has run its course recently in some of the pop-sci work asking questions like, "What would happen to the earth, if all the humans disappeared."

This article from New Scientist claims, "...it will only take a few tens of thousands of years at most before almost every trace of our present dominance has vanished completely. Alien visitors coming to Earth 100,000 years hence will find no obvious signs that an advanced civilisation ever lived here. ... Yet if the aliens had good enough scientific tools they could still find a few hints of our presence."

Ocean sediment would revel our industrial revolution, as would other lasting indicators.

Of course, you're asking about a pre-industrial society living 15-million years ago, so some of the more esoteric evidence wouldn't exist.

Still, if our own history is any guide, there would be examples of fossil record of a mass extinction of flora and fauna coinciding with the rise of civilization. Not sure how you'd distinguish this from a more "natural" extinction incident though...

I suspect that some forms of evidence would survive no matter what.

Of course, billions of years from now, long after the surface of the earth has been rendered lifeless by a relentlessly expanding sun, the name Richard M. Nixon will live on. It's written on one of the Apollo moon plaques, left on the surface of the moon. In the vacuum of space it will survive billions of years until the earth and moon are engulfed by the sun.
posted by wfrgms at 8:31 PM on May 28, 2009 [3 favorites]

Oh, I should add, about that show: the episode off the torrent sites is, I think, the pilot of the show that goes through the science gradually, year by year after people disappear.

But the show is a series. I haven't seen the rest of the episodes but it looks like it goes into some things you might find helpful, like what happens to some of the bodies, or metals, etc.

Again, not everything will apply to a Renaissance-level civilization, but some stuff would. What a lot of the show does is look at previous civilizations and what remains of them, so there's definitely some good stuff there to help you think about the things in your question.
posted by Nattie at 8:31 PM on May 28, 2009 [2 favorites]

No I don't think it could be found. Like a needle in a hay stack. Was there a seed that planted us here? most likely. Was it the 1st? Who knows
posted by patnok at 8:32 PM on May 28, 2009

Oh, also, we have stone tools used by Homo habilis going back two million years or so. It's not a stretch to imagine those tools surviving for another 13 million to meet your time frame. And that's tools used by our earliest known ancestor.

Also, your window of 100,000 years (for the civilization to arise and disappear) is interesting. Homo habilis was roaming around for about million years and we only know of them through about four or five surviving fossils and handfuls of tools.
posted by wfrgms at 8:40 PM on May 28, 2009

Best answer: The evidence wouldn't be so much what they left as what they took.

A society as advanced as you describe would do extensive mining of mineral ores and stone, and evidence of that mining would be detectable today.
posted by Chocolate Pickle at 9:21 PM on May 28, 2009

"metal ores" that should have been.
posted by Chocolate Pickle at 9:22 PM on May 28, 2009

An interesting question, with good answers so far. Another way to frame it is to ask how many civilizations could have arisen and vanished over the history of the earth, given the constraints of the fossil record. You're wondering whether the answer is "one" or "two." But if you could have had a civilization arise and vanish 15 Myr ago, why not 30 Myr? and 45 Myr? and so on. Ours could be the fifth civilization since the fall of the dinosaurs, by this reckoning.

Singled-celled orgainsms appear in the fossil record only 3500 Myr ago, only 1000 Myr after the formation of the earth, but multi-celled organisms apparently didn't take off until the "Cambrian explosion" in the last 500 Myr. How many previous Cambrian explosions fizzled? If the timescale to evolve superweapons is 500 Myr, we could be the eighth. But that doesn't square with the fossil record of the history of the chemistry of the atmosphere, which suggests that oxygen became dominant during the Cambrian following the development of photosynthesis.
posted by fantabulous timewaster at 9:34 PM on May 28, 2009

A society as advanced as you describe would do extensive mining of mineral ores and stone, and evidence of that mining would be detectable today.

If there had been a major Ice Age in between them and us, it might not be that obvious; plus you have ongoing continental drift messing around with all the mountain ranges and other geology. I don't think it would take that much movement of the Earth's crust to hide the relatively small amount of material disturbed by mining, at least as it was practiced in the Renaissance and before. They went mostly for fairly shallow deposits and didn't move huge quantities of overburden around, which seems like it would be the most obvious signs.

If the past civilization were more modern -- more like our own -- there would probably be glaringly obvious signs for a very long time afterward, if anyone cared to analyze the distribution of radioactive isotopes in the atmosphere, oceans, and on the surface, and compare it to 'dead' planets in the solar system. I suspect in fact that you could date with a fair amount of reliability when a nuclear civilization expired (or ceased doing anything with nuclear reactions) to a fair degree of precision by looking at the fission products. (It would be especially obvious if they wiped themselves out via nuclear war.) I don't think there's any way such a thing could have plausibly happened in the Earth's past, but it's a scenario I once spent a few beers bullshitting about with some JPL folks. Because of the very long time the universe has been around, some people believe there's a much greater chance of finding a planet that used to have life or even civilization, than one that has it right now. Unfortunately I don't think it's the sort of thing you can do remotely, so it's purely hypothetical.
posted by Kadin2048 at 10:49 PM on May 28, 2009

The World Without Us by Alan Weisman is a recent book and a good read. He examines when and how the objects in our civilization — streets, tunnels, skyscrapers — would crumble and degrade if the human species became extinct, and what traces would remain to show that a civilization was here.
posted by exphysicist345 at 11:01 PM on May 28, 2009

I agree that things like pyramids and deep mines could possibly leave evidence but they could also possibly be wiped out by tectonic activity in 15 million years. Look at this animation, for example: 15 million years ago India hadn't fully merged with Asia yet so if the hypothesized civilization formed in one of the valleys between those land masses both pyramids and deep mines would have been wiped out.

Lots of it would really depend on exactly what sort of renaissance-level technology they developed. We of course don't know how many much more recent civilizations may have developed that didn't decide to build big piles of stone or burial mounds. I saw a documentary about an anthropologist who believes that there was an extensive and heavily-populated civilization in the Amazon that we have missed because all they really left behind was especially deep terra preta dirt.

I think that some of the best material for hearing the echoes of the most ancient civilizations would be through linguistic reconstruction but unfortunately most of the languages on Earth are dying or gone.
posted by XMLicious at 11:04 PM on May 28, 2009

Just an interesting perspective from another time which I always found interesting in its prescience:

Suppose, for example, that the city of Sparta were to become deserted and that only the temples and foundations of buildings remained; I think that future generations would, as time passed, find it very difficult to believe that the place had really been as powerful as it was represented to be. Yet the Spartans occupy two-fifths of the Peloponnese and stand at the head not only of the whole Peloponnese itself but also of numerous allies beyond its frontiers. Since, however, the city is not regularly planned and contains no temples or monuments of great magnificence, but is simply a collection of villages, in the ancient Hellenic way, its appearance would not come up to expectation. If, on the other hand, the same thing were to happen to Athens, one would conjecture from what met the eye that the city had been twice as powerful as it in fact is.

—Thucydides, The Account of the Peloponnesian War [circa 400 B.C.] Book I, Chapter 10
posted by koeselitz at 11:11 PM on May 28, 2009 [15 favorites]

By the way, I feel as though a society could disappear leaving no trace, not only in the space of 15 million years, but even in a thousand years; in extreme cases, I imagine that there are certainly natural disasters and cataclysmic events that could wipe out civilizations of a certain size.

I know this isn't a new idea, either; not only did Thucydides ponder something like what you're asking, but Plato's Socrates explicitly theorizes (in the Timaeus) that this is possible, and opines that whole civilizations might have come into being and completely and utterly disappeared in the past without anyone knowing about them through, for example, floods or massive earthquakes. I tend to believe that, not only is this possible, but more happened in the past which we do not and will not ever know than we tend to imagine in these “data-heavy” times.
posted by koeselitz at 11:23 PM on May 28, 2009 [1 favorite]

THE PSYCHOLOGY OF "CRACKPOT" ARCHEOLOGY!

Weird ancient artifacts might exist. But how could there ever be valid and accepted evidence for them?

Well, what actually happens if someone finds an advanced artifact in ancient strata? Gold jewelery in coal mines, arrowheads in triassic strata, etc. Or even arrowheads 200K years earlier than valid finds? First, the provenance must be airtight, or the evidence will be labeled fraudulent or a product of incompetence. Second, evidence against mixing of strata must be airtight (no crevices with material falling from above, no fossil prarie dog burrows, etc.)

But then the evidence must survive the hostile disbelief of fellow professionals. Since hoards of Creationists and Forteans love any "out of place artifact" which casts archeology in a bad light, there's little chance that such evidence would be taken seriously, even if presented by a trusted senior researcher. If the evidence looks crazy, it will be rejected, and the claimant's reputation damaged. The trustworthyness of the claimant doesn't bring the evidence higher, instead the crazy evidence drags down the researcher.

Whether any such evidence exists or not, this sets up a mechanism for "self-fulfilling prophecy," and for the suppression of "outlier" evidence. Since we *know* that there aren't any such civilizations, then anyone finding evidence is not proving the civilizations, they're only proving their own insanity. (This problem, when arising in theoretical physics is known as "Experimenters' Regress.)

So, if you're working on a dig, and you find a fossil transistor radio, or billion-year-old human bone or gold necklace ...throw it away. Or better yet, smash it to powder. Such things don't exist, so if you actually FIND one, it can only cause major career trouble.

There are plenty of odd books about these topics, books describing huge loads of anomalous finds which are totally rejected by contemporary science. No doubt most finds are fraudulent, or the product of mistakes. Perhaps all of them are. However, if really old technological societies are buried in the rock, the evidence has long been known, and will be found sitting there for all to read in the crackpot literature, sitting side by side with the genuinely crazy dreck.

A good book on crazy finds: Michael Cremo, FORBIDDEN ARCHEOLOGY
posted by billb at 12:03 AM on May 29, 2009 [2 favorites]

The gist of it was that after 500 years, even the really big monuments like the Eiffel Tower would be gone.

I drove past Stonehenge yesterday, it seemed to still be there.
posted by biffa at 2:30 AM on May 29, 2009 [3 favorites]

I suppose one of the major factors would be how this (by definition) pre-historic civilization came to an end. One of the features that would, almost by necessary implication, exist with a civilization is an awareness of mortality. Thus, since your hypothetical includes architecture, there would be efforts to make things LAST, as well as efforts to protect against cataclysm.

Thus, there might not be specific evidence of this civilization, but I would expect that signs of what led to its doom to remain, in that I have difficulty accepting that simple natural processes, no matter how powerful, would lead to a complete elimination of this otherwise advanced creature.
posted by birdsquared at 3:09 AM on May 29, 2009

...I would expect that signs of what led to its doom to remain...

That doesn't seem like a tenable hypothesis. Evidence for the Justinian Plague, for example, is the absence of archaeological record - the fact that archaeological markers stop over a widespread area in the year of the plague.

Or something like a catastrophic famine or other cataclysm might actually be evident in archaeological traces but you couldn't tell that it ended a civilization unless you already knew the civilization had been there.

Also, why would an understanding of architecture mean that you'd try to make things last? Just because you understand how columns work doesn't mean that you automatically try to make them out of stone instead of wood or iron.
posted by XMLicious at 3:31 AM on May 29, 2009

Maybe Cahokia and the Mississipian culture are a useful starting point?
posted by dilettante at 3:56 AM on May 29, 2009

I drove past Stonehenge yesterday, it seemed to still be there.

i don't think we've abandoned it yet.
posted by lester at 5:30 AM on May 29, 2009 [1 favorite]

Best answer: Ice Age glaciers would wipe everything out. But stone monuments in tropical regions should last. A pyramid is nothing more than a big pile of rocks, and rocks last.

When you see stone "ruins," they are ruined not because the stone and cement fell apart -- cement is essentially artificial rock -- but because locals pillaged the stones for cheap, precut building materials.

The question is whether the rocks would weather out. The Great Wall of China would weather in the rain, but the line it traces might be there for quite a while. Though not, perhaps, 15 million years. On the other hand, the pyramids in Mexico would likely get buried by the jungle. That would protect them. Deep radar might find them.

It's hard to imagine the Hoover Dam disappearing, but 15 Myr is such a long time, the river might scrape it away in its entirety.

Cities ought to be detectible even if every building collapsed. The stones would still be there, and archeologists would notice that certain places had a superabundance of minerals -- iron ore, for example. Since no geological process would concentrate iron ore like that, a clever archeologist would suppose that something must have put all that ore there.

Gold might last. Gold items should remain unchanged. Gold is chemically inert.

But it really only takes one fossilized circuitboard -- or tiara -- to blow the whistle on your ancient civilization. Somewhere, something would get buried under dirt, and compressed, and protected by the compressed silt. And someone would split the limestone apart later and learn the truth.
posted by musofire at 5:37 AM on May 29, 2009

The Hoover Dam wouldn't last long at all. Dams require a lot of maintenance and operations to keep from crumbling.
posted by argybarg at 6:08 AM on May 29, 2009

Seeing as parrots are pretty smart, I'm hoping scientists may some day find ruins of intelligent, social dinosaur societies. Maybe in 100 years we'll have more advanced imaging equipment, allowing us to "see" below the sea beds.
posted by bonobothegreat at 6:21 AM on May 29, 2009

Best answer: Maybe in the fossil record we would see a die-off of big mammals and try to figure out why that had happened, or find fossilized bones with knife marks or something like that. Fossils last over 15 million years.
posted by salvia at 7:49 AM on May 29, 2009

How long would underground cables last? Huge quarries? Nuclear test sites? Cliff Richard?
posted by biffa at 8:06 AM on May 29, 2009

Another historical perspective, concerning Britain's time as a Roman province:

In this period, almost equal to that which separates us from the reign of Queen Elizabeth I, well-to-do persons in Britain lived better than they ever did until late Victorian times. From the year 400 until the year 1900 no one had central heating and very few had hot baths. A wealthy British-Roman ciizen building a country house regarded the hypocaust which warmed it as indispensable. For fifteen hundred years his descendants lived in the cold of unheated dwellings, mitigated by occasional roastings at gigantic wasteful fires. Even now [1930-something] a smaller proportion of the whole population dwells in centrally heated houses than in those ancient days.

-- Winston S. Churchill, A history of the English-speaking peoples, 1956.

Of course Roman Britain isn't "lost" in the sense you're wondering about, but like Thucydides's observation about Athens and Sparta it's striking how little remained of that dominant civilization.
posted by fantabulous timewaster at 8:12 AM on May 29, 2009 [1 favorite]

For some ideas about the permanence of nuclear processes you might read about the Oklo natural reactor, a rich uranium deposit which filled with rainwater 2 Gyr ago and fissioned several tons of uranium over some thousands of years.
posted by fantabulous timewaster at 8:20 AM on May 29, 2009

Argybarg: I recall reading a speculaton long ago that the Hoover Dam would quickly stop functioning after a lack of maintenance. However, the massive concrete structure itself would survive for 20,000 years, until floods from the end of the next ice age. At that point it would break into tall cells, representing the individual concrete pours that make up the structure.
posted by Midnight Skulker at 8:47 AM on May 29, 2009

I read a science fiction story once that that featured a gold ring found in a very old volcanic ash deposit.
posted by Bruce H. at 3:05 PM on May 29, 2009

Interestingly, the longest lasting human relics will probably be the stuff left on the moon by the Apollo astronauts.
posted by Chocolate Pickle at 9:39 PM on May 29, 2009 [1 favorite]

I drove past Stonehenge yesterday, it seemed to still be there.

i don't think we've abandoned it yet.

How long do you think it has been curated?
posted by biffa at 2:22 PM on May 31, 2009