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The Silurian Hypothesis (2020)

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Re: The Silurian Hypothesis (2020)

#71

Post by GolfPopper »

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...

Re: The Silurian Hypothesis (2020)

#72

Post by netbioserror »

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.

Re: The Silurian Hypothesis (2020)

#73

Post by davidbjaffe »

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.

Re: The Silurian Hypothesis (2020)

#74

Post by api »

Razengan wrote: post #12
api wrote: post #7

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.

> 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.

Re: The Silurian Hypothesis (2020)

#75

Post by sgt101 »

graemep wrote: post #28
dash2 wrote: post #20

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?

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).

Re: The Silurian Hypothesis (2020)

#76

Post by Diogenesian »

jerf wrote: post #25
markus_zhang wrote: post #13

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 clear…

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.

Re: The Silurian Hypothesis (2020)

#77

Post by MrDrMcCoy »

graemep wrote: post #28
dash2 wrote: post #20

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?

Or it stayed concentrated for a long time until local conditions forced a scattering.

Re: The Silurian Hypothesis (2020)

#78

Post by [deleted] »

AlotOfReading wrote: post #64
graemep wrote: post #28

Earlier quoted context omitted.

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…

[deleted]

Re: The Silurian Hypothesis (2020)

#79

Post by MrDrMcCoy »

xg15 wrote: post #4

> 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.

Re: The Silurian Hypothesis (2020)

#80

Post by xg15 »

GolfPopper wrote: post #71

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…

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...

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