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zhamid
2009-Feb-09, 01:57 AM
Hi,

Lets say Earth had intelligent life a couple of hundred million years ago. A few extinction cycle later, will we actually be able to determine the existence of intelligent life back then?

Or putting it the other way, say global warming (human caused or not) changes our environment drastically and starts mass extinction. Life evolves again and will likely go through another extinction cycle. A few hundred million years later another intelligent life evolves on Earth. Other than looking at artificial satelites or stuff on the moon, will they be able to look at things on Earth and say conclusively that we existed a few hundred million years ago? By then I imagine continents will be different, mountains will be different ...

hhEb09'1
2009-Feb-09, 02:56 AM
Hi,

Lets say Earth had intelligent life a couple of hundred years ago. A few extinction cycle later, will we actually be able to determine the existence of intelligent life back then?

Or putting it the other way, say global warming (human caused or not) changes our environment drastically and starts mass extinction. Life evolves again and will likely go through another extinction cycle. A few hundred million years later another intelligent life evolves on Earth. Other than looking at artificial satelites or stuff on the moon, will they be able to look at things on Earth and say conclusively that we existed a few hundred million years ago? By then I imagine continents will be different, mountains will be different ...Did you mean "a couple of hundred million years ago" in the first line?

Artifacts will probably remain. An interesting book in this regard is The World Without Us, a speculation about the world if we should go extinct.

zhamid
2009-Feb-09, 04:02 AM
Will they though, for that long? The landscape may be completely different. Continents may combine and break apart again. Oceans may flow where there's land and we may have land when there's ocean today.

I'll check out the book.

WayneFrancis
2009-Feb-09, 04:32 AM
Will they though, for that long? The landscape may be completely different. Continents may combine and break apart again. Oceans may flow where there's land and we may have land when there's ocean today.

I'll check out the book.

First I'd have to ask you what you mean by intelligent. What is the boundry?
All the great apes and a few other animals are found to be intelligent. All great apes create and use tools and have been defined to have culture. More and more we are finding out that other species do have "language" even if it isn't in the same grammatical sense as ours. I'll go with a species that uses tools.

While most building would crumble away some things could and probably would last for a very long time or would leave traces behind.

Just as bone fossilize one would expect that an intelligent specie's tools would also leave signs behind much like fossils even if the original items have been destroyed.

The fact that we haven't found these types of signs from over a hundred million years ago isn't the smoking gun that there wasn't there. We might not have found the evidence. There was little chance of a species being anywhere near as advanced as we where even a few thousand years ago. This is because we would see fossil evidence of such a species everywhere as they would most likely have come to inhabit the world just as we did if they had the same level of technology.

Tarkus
2009-Feb-10, 01:32 AM
I reckon breast implants will be littered all over - the only trace left of us...

dhd40
2009-Feb-10, 02:35 PM
The fact that we haven't found these types of signs from over a hundred million years ago isn't the smoking gun that there wasn't there. We might not have found the evidence. There was little chance of a species being anywhere near as advanced as we where even a few thousand years ago. This is because we would see fossil evidence of such a species everywhere as they would most likely have come to inhabit the world just as we did if they had the same level of technology.
(my bold)

I donīt think so. Plate tectonics and subduction processes could have removed each and every trace of it. But, of course, geologists might tell us that this needs a billion years instead of 100 million years?

hhEb09'1
2009-Feb-10, 03:52 PM
I donīt think so. Plate tectonics and subduction processes could have removed each and every trace of it. But, of course, geologists might tell us that this needs a billion years instead of 100 million years?Continental crust (where people mostly live) is not usually subducted. It can be eroded, and lowered by tectonics and fllooded with sedimentation, but it is also uplifted by tectonics, and exposed by erosion. Most of the fossils we have from billions of years ago have been found at or near the surface.

WayneFrancis
2009-Feb-11, 03:43 AM
(my bold)

I donīt think so. Plate tectonics and subduction processes could have removed each and every trace of it. But, of course, geologists might tell us that this needs a billion years instead of 100 million years?

Sure it could have but then you would not have any fossils from that same period and location. If fossils of bone and tissue survive from a period and location one would expect that we would be able to see some traces of "technology" from that same period. The rules for the creation of "fossil tools" would be much the same for fossil bones and there is even more possibilities that advanced materials would not weather as fast as normal materials. Teflon for example we would expect to be around for many many years. Since it is both hydrophobic and oleophobic, has a naturally dense structure and is chemically inert it will last a VERY long time. Compare this to bone and when you realize that we still have evidence of bone from over 350 million years ago then it isn't hard to see that if there where advanced civilizations back during that time period then we would expect to see some evidence for it.

dhd40
2009-Feb-11, 01:01 PM
Continental crust (where people mostly live) is not usually subducted. It can be eroded, and lowered by tectonics and fllooded with sedimentation, but it is also uplifted by tectonics, and exposed by erosion. Most of the fossils we have from billions of years ago have been found at or near the surface.(my bold)

Ah, I wasnīt aware of this. Youīre right, indeed.

http://en.wikipedia.org/wiki/Fossil


fossils range in age from the youngest at the start of the Holocene Epoch to the oldest from the Archaean Eon several billion years old (my bold)

dhd40
2009-Feb-11, 01:13 PM
... Teflon for example we would expect to be around for many many years. Since it is both hydrophobic and oleophobic, has a naturally dense structure and is chemically inert it will last a VERY long time. ....

Thermal decomposition of Teflon starts at about 400°C. It would not "survive" for a long time on Venus. If Earthīs climatic disaster continues to ....:whistle:

Otherwise, I agree with your arguments, see also my reply to hhEb09ī1

WayneFrancis
2009-Feb-11, 01:34 PM
Thermal decomposition of Teflon starts at about 400°C. It would not "survive" for a long time on Venus. If Earthīs climatic disaster continues to ....:whistle:

Otherwise, I agree with your arguments, see also my reply to hhEb09ī1

Well then you are changing this from the original post too. The question was


Lets say Earth had intelligent life a couple of hundred million years ago. A few extinction cycle later, will we actually be able to determine the existence of intelligent life back then?

And while climate change is bad for us...it isn't really bad for the world as a whole long term.

As things stand "intelligent life" being defined as a species that has some type of technology should leave traces of that technology that we would be able to find even a few hundred million years later.

You might as well say "If a comet 500km in diameter hits the earth it will destroy all this evidence. My point stands. If fossils of life exist for that time and location then there is a good chance that fossil like evidence of their technology would expected to be also present.

zhamid
2009-Feb-12, 05:22 PM
thanks. I guess that makes sense. But in this case the argument is that we'll see evidence for an advanced civilization. I understand that. We'd see satellites and stuff too.

But if humans went extinct only 10,000 years ago then would we have left enough evidence behind? I doubt a few hundred million years from today 10,000 year old tools and stuff would necessarily be fossilized in easily discoverable ways, even though humans from 10,000 years ago were likely just as intelligent as humans from today. Imagine if humans never reached beyond simple agriculture before going extinct...

I started another thread on the diversity of life: http://www.bautforum.com/astronomy-cast/84682-difference-between-life-forms.html#post1433438. Imagine if 300 million years ago there were highly intelligent exoskeleton based marine life that had complex communication (not necessarily language the way we have), organized itself in societies and created and used tools (again, would be drastically different from what we have). Would we even recognize them today? What they even have survived this long in form we can find and recognize?

WayneFrancis
2009-Feb-14, 01:07 PM
well I'm not sure we don't have that now. Many people thing that humans are so much different then other animals but I don't see that as true. There is nothing that humans and our culture does at a basic level that other species don't also do.

The fact is we do find signs of tools that are tens of thousands of years old.

As far as tools being found ... I think the tools would have to be modified in some way from the natural materials for us to realise the use. For example sea otters use stones to open up shell fish while floating in the ocean. These tools would not be recongnised by us as the stones themselves are not modified in any consistant manner. In a similar vein I'm not sure that some of the basic tools other great apes make and use would be distinguishable from the materials they are made from for the most part. Once a species gets into the "Stone age" and starts highly modifing stones in a consistant manner for a given task I think those signs would be more and move visible to the scientist in the different fields.