The Silurian Hypothesis

[crazy canuck]

What about, though, if a previous civilization engaged in climate engineering (intentionally or otherwise)... could we possibly detect that?  Like a previous global warming or cooling event not otherwise explained?  How could we come to the conclusion it was caused by a civilization... or could we?

Well as I understand it, we have good records through ice cores about ancient temperatures, but such evidence only goes back a few hundred thousand years.

A slight quibble, given the time periods we are talking about.  The oldest ice core is from 2.7 million years ago.


https://www.sciencemag.org/news/2017/08/record-shattering-27-million-year-old-ice-core-reveals-start-ice-ages

[The Brain]

It is an entertaining what-if but unless we talk about a very small population secluded species reaching the earliest stages of Stone Age civilisation, I just can't believe we would not have found traces of them. Not possible.

I find it interesting to speculate about "what if the velociraptors reached sentience and had a stone age civilization" but I don't think anyone thinks that with our current level of technology we'd be able to uncover a primitive civilization like that.  I think the concession is that we would need a past civilization to have deposited layers of radioactive material in order for there to be any chance at all of detecting them, right?

Not necessarily depositing layers, local remains of nuclear reactor fuel (likely identified by lower levels of U-235) from an era in which natural reactors weren't possible would be very strong evidence for an old civilization. The Oklo reactor of course is a nice demonstration of what could be learnt. Oklo was old enough to be natural, but was it necessarily natural???!? 

[Malthus]

It is an entertaining what-if but unless we talk about a very small population secluded species reaching the earliest stages of Stone Age civilisation, I just can't believe we would not have found traces of them. Not possible.

I find it interesting to speculate about "what if the velociraptors reached sentience and had a stone age civilization" but I don't think anyone thinks that with our current level of technology we'd be able to uncover a primitive civilization like that.  I think the concession is that we would need a past civilization to have deposited layers of radioactive material in order for there to be any chance at all of detecting them, right?

We would, if we found their tools. The "stone age" is so named because people at that level of civilization used stone tools ... and if fossils can survive, so can stone tools.

The issue would be whether any were found.

[jimmy olsen]

It is an entertaining what-if but unless we talk about a very small population secluded species reaching the earliest stages of Stone Age civilisation, I just can't believe we would not have found traces of them. Not possible.

I find it interesting to speculate about "what if the velociraptors reached sentience and had a stone age civilization" but I don't think anyone thinks that with our current level of technology we'd be able to uncover a primitive civilization like that.  I think the concession is that we would need a past civilization to have deposited layers of radioactive material in order for there to be any chance at all of detecting them, right?

If we found fossils with a skull like this thing would have, then I'm pretty sure some scientists would go out on a limb and say it was intelligent.

[Eddie Teach]

Just how many hundred million year old fossils have we found? I'd imagine many species haven't been discovered or identified.

[Barrister]

What about, though, if a previous civilization engaged in climate engineering (intentionally or otherwise)... could we possibly detect that?  Like a previous global warming or cooling event not otherwise explained?  How could we come to the conclusion it was caused by a civilization... or could we?

Well as I understand it, we have good records through ice cores about ancient temperatures, but such evidence only goes back a few hundred thousand years.

A slight quibble, given the time periods we are talking about.  The oldest ice core is from 2.7 million years ago.


https://www.sciencemag.org/news/2017/08/record-shattering-27-million-year-old-ice-core-reveals-start-ice-ages

That's really cool!

[Malthus]

Just how many hundred million year old fossils have we found? I'd imagine many species haven't been discovered or identified.

100 million years is not that long ago, in fossil terms.

I can go into my back yard, turn over some rocks, and find 450 million year old fossils - Ordovician shale. The problem is not too few, it is too many - 99.9% of such fossils are boring, so you have to look through thousands of rocks filled with crinoid stems and shells to find a single trilobite; much invertebrate paleontology is done by amateurs, who do it for a hobby.

Lots of species have been found, but obviously a drop in the bucket compared with how many that existed - but then, we haven't identified the species that exist right now, let alone in fossil form.

https://www.amnh.org/our-research/paleontology/collections/fossil-invertebrate-collection/trilobite-website/gallery-of-trilobites/ordovician-period-trilobites

Here's some 500 million year old fossils with soft parts preserved, which is admittedly rare:

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

[alfred russel]

What about, though, if a previous civilization engaged in climate engineering (intentionally or otherwise)... could we possibly detect that?  Like a previous global warming or cooling event not otherwise explained?  How could we come to the conclusion it was caused by a civilization... or could we?

Well as I understand it, we have good records through ice cores about ancient temperatures, but such evidence only goes back a few hundred thousand years.

Otherwise, we can infer what ancient climates were like through what kinds of vegetation is preserved in fossils.

Problem is if there was a rapid change in climate, that then lead to the extinction of the Silurian technological society, suich an event likely happened to quickly (geologically speaking) that not enough material would be deposited to ever be able to find.

You were one of those that was attacking me for theorizing about a civilization at the time of the oxygenation of the atmosphere, about 2.5 billion years ago.

[Caliga]

Not necessarily depositing layers, local remains of nuclear reactor fuel (likely identified by lower levels of U-235) from an era in which natural reactors weren't possible would be very strong evidence for an old civilization. The Oklo reactor of course is a nice demonstration of what could be learnt. Oklo was old enough to be natural, but was it necessarily natural???!?

Hey I had totally forgotten about that 'natural nuclear reactor'.  Is that the only one that has ever been found?

[The Brain]

Not necessarily depositing layers, local remains of nuclear reactor fuel (likely identified by lower levels of U-235) from an era in which natural reactors weren't possible would be very strong evidence for an old civilization. The Oklo reactor of course is a nice demonstration of what could be learnt. Oklo was old enough to be natural, but was it necessarily natural???!?

Hey I had totally forgotten about that 'natural nuclear reactor'.  Is that the only one that has ever been found?

I don't know of any other areas where they have been found.