The possibility of pre-human civilizations on earth?

Has it ever been seriously investigated whether the idea of earlier intelligent beings on earth, with associated civilizations, is plausible? Do we know enough, or do we have the means, to determine whether this can be confidently excluded, or that it still is an open question instead?I was wondering whether a civilization of the level of, say, the Romans, would leave ANY traces if it would have existed 30 million years ago or so. I don't necessarilly envision this as hominids, but as any lifeform that would be able to transform its environment to the same degree as that culture.I think it is an interesting question because the answer has so many implications. I always found it striking that the emergence of homo sapiens and the civilizations it produced took so little time. I mean, there was 3 billion years of evolution without anything similar (as far as we know?), and suddenly in less than 1/1000th of that time you have the emergence of intelligence and all associated developments. You would think that there is a good chance that evolution produced "intelligence" multiple times, just like the eye has evolved multiple times.I already see one argument that makes it unlikely that such civilization(s) would have gone by unnoticed. And that is that the evolution of intelligent civilizations (a matter of thousands of years) seems to be so fast that it takes just a blink of an (evolutionary) eye to go from zero to our current technology. This of course assumes that intelligence is always as self-amplifying as it seems to be in our case. But it would mean that such a civilization is unlikely to be broken off at early levels. A natural mass-extinction event would be really bad luck over such a small time-interval, and the abilities to self-destruct take more time to develope and would result in leaving behind much more advanced 'transformation of environment'; a civilization of our level would be more likely to leave traces after such time(?)On the other hand, how thin is the layer in the geological collumn that corresponds with 5000 years, anyway?

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Well, we've dug far enough to find much more than traces of dinosaurs, which didn't have the ability to transform their environment anywhere nearly as much as an advanced civilization, and those haven't been around for roughly 65 million years, so I gather we'd have found more than a few signs of any civilization that existed roughly half that long ago. We haven't and not for a lack of looking, so I say no.

Evos like to point out the "extreme rarity" of fossil finds, and point to erosions, etc,...in defense of the accusations that if ToE were true, there would be many more, vastly so, clear-cut transitionals seen.Not to sidetrack the point, and for the record, I tend to think we don't see the transitionals because they did not occur, but just looking at things from mainstream science, the OP makes a good point.Rapid evolution of what we think of as high intelligence and technology occurs in a blink of an eye, assuming evo-dating is correct. If an advanced, super-intelligent civilization emerged 30 million years ago, it might not leave much behind.Moreover, it is likely the data that would be left behind would be explained away since it wouldn't fit the current paradigm.

Star Trek Voyager presented such a scenario. They said that a dino species was able to achieve intelligence and launched themselves into deep space when the planet faced a planet wide disaster, probably the one that caused the extinction of the dinosaurs.

Okay, couple of definitions-First off, by "human", I'm going to assume you mean hominid, since depending on your definition of human, one could point to Neanderthal or Homo Habalis.Second, by "civilization", I'm going to assume you mean a culture of material remains (ie buildings, tools, etc.)If that's the case - no, there is no evidence for it, and given the amount of time spent looking, it's doubtful there will ever been any evidence. In other words, unlikely that it ever existed.However, if by "civilization" you mean common language, common ritual, etc. One could argue that there have likely been several pre-human civilizations.A species' intelligence does not necessarily translate into material remains. Squids and octopus are intelligent, but their short lifespan and lack of need for "tools" or "buildings" mean that despite millions of years, there's no evidence for this intelligence.Same with dolphins, or elephants, etc.And it's not just "need" for material remains that dictates their existance. I'm sure that elephants would do quite nicely if they had houses. However, with only a nose to build them... you get the idea.Additionally, the availability to material is a major factor. Let's say there was a super intelligent species of dinosaur, but all they had to work with was wood tools. None of that is going to be around today for us to see.

My thoughts are that even with Roman-level technology a species that developed a civilisation would be widespread and numerous and therefore relatively likely to be represented in the fossil record.And while organic materials and most metals would not survive I would have thought that we might hope to find remains of stonework (perhaps foundations). But I'll defer to anyone with relevant expertise on that one.Even then I can't say that it is necessarily the case that something would have survived and been discovered.

I can't really say much about 'serious' investigation of the possibility. You could speculate about it but it wouldn't go anywhere until you found a city from before the Holocene. I do know that H.P. Lovecraft dealt with the scenario at least once in his short-story "The Shadow Out Of Time", in which Earth plays host to a number of species endemic to the planet through different stages of its history as well as the Elder Gods and higher-dimension beings of the Ctulhu mythos, which are their enemy.I do think that if such a civilization ever existed since the Mesozoic or so, it should be represented in the rock record (where we should have found it by now) you run into problems much before that because there don't seem to have been land creatures likely to attain intelligence. The only really positive thing I can say about it is that only a relatively small percentage of land-deposited sediments are actually preserved in the the geologic record. The problem is that an intelligent species is likely to be highly adaptable and tend to cover all the inhabitable areas of the planet.Spacefaring civilizations would be easiest to detect by exploring the Moon, where nothing much has happened geologically in the last couple billion years.This message has been edited by gene90, 09-13-2005 11:54 PM

Some good points...I agree that there probably would be traces left and that you need a pre-history of organisms that could lead to something intelligent.There might be one intriguing possibility left: that the civilization and the organisms that came before it existed even LONGER ago, and on one isolated landmass that was later completely submerged into the crust by plate tectonics? Is this conceivable, given our undestanding of plate tectonics?Of course, it would never be possible to really check that out...

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There might be one intriguing possibility left: that the civilization and the organisms that came before it existed even LONGER ago, and on one isolated landmass that was later completely submerged into the crust by plate tectonics? Is this conceivable, given our undestanding of plate tectonics?

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Well, actual continents tend to be conserved by plate tectonics. That's because they are made out of granitic rocks that tend to be bouyant--so they dont go down into trenches and get recycled.If there were a hypothetical civilization on an island arc, like modern-day Japan, for example, evidence might not be preserved until today because plate tectonics tends to plaster such arcs against the sides of continents and metamorphism will go a long way to erase whatever evidence might be in them.Anything that were on ocean crust, like shipwrecks or what have you, is ultimately doomed by tectonics since it regularly gets recycled.This message has been edited by gene90, 09-15-2005 12:39 AM

Fo' show, dirty.I don't think this is the 1st time I've suggested this book on this forum but whatever.This book Fingerprints of the Gods : The Evidence of Earth's Lost Civilization was excellent. It offered much evidence for a pre-ice age global crossing civilization. I'd suggest it to anyone. It was well written and the evidence was respectable, somewhat.I could post in a whole thread devoted to this book, if I still had it in my possesion and could look up stuff in it. I think it be a good thread though if others have read this book. Hell, I might even go buy it again.

I'd question that. From the accounts I've heard Hancock is something of a sensationalist and relies on a skewed (at best) presentation of the evidence. I'd place him somewhere between Erich von Daniken and David Rohll

must have missed that episode. sounds like a good one.and maybe plausible, too. some of the theropod dinosaurs seem to have gotten pretty intelligent, maybe comparable to today's dolphins. maybe. but there's no evidence of any technology, the real defining characteristic of intelligence and civilization.

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There was one very implausible element in it though: they had the computer extrapolate the evolution of a dinosaur into the dinoid species, based purely on the genome. And guess what? The likeness of the result with the actual species was uncanny.It's a very unlikely scenario, because you cannot possibly know which mutations are going to take place and what selective pressures are in force.But even though it presented a travesty of the principles of evolution, it was a nice story anyway.

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We are all atheists about most of the gods that humanity has ever believed in. Some of us just go one god further. - Richard Dawkins

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I'd question that. From the accounts I've heard Hancock is something of a sensationalist and relies on a skewed (at best) presentation of the evidence. I'd place him somewhere between Erich von Daniken and David Rohll.

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I bristle a bit at seeing his works on the science shelves of bookstores. Here's one I see more often than Fingerprintshttp://www.amazon.com/...32/ref=pd_sbs_4/104-4610221-7878304I still say that other planets would probably be the best place to look for previous spacefaring human civilizations, when you get into NASA finding and covering up such artifacts, I lose interest.