[GraceG]

I think between now and 500,00 years ago we have had several civilizations that have prospered then died out to have evidence wiped away by glacial till.

I think people rise up, create civs and then decadence makes it all crash down.....

Time is repeat..

[NormsRevenge]

I guess the technologies that they didn’t seem likely to develop on their own are still a stumper for me.

Somebody borrowed them some nifty tools or ??

We were never alone. (The Bill Clinton defense gone cosmic)

[UCANSEE2]

Life, a single life, the nation’s life, a civilization’s life is like a bell curve. Which is why Hemingway wrote ‘For whom the bell tolls’.

: )

[1010RD]

That’s the premise of these books: http://www.amazon.com/Angel-Sword-Merovingen-Nights-Book/dp/0886771439/ref=pd_sim_b_4?ie=UTF8&refRID=1WJC2MT6VDCQ726QK34H

[Smokin' Joe]

I think between now and 500,00 years ago we have had several civilizations that have prospered then died out to have evidence wiped away by glacial till.

I live near the margins of the last great ice sheet in North America. I have often wondered what existed to the north along rivers which have changed their courses since, now bulldozed by the glaciers and overlain by till. We may well find humans were here far longer than even the pre-Clovis cultures only now being noted.

[<1/1,000,000th%]

In between glaciations.

[minnesota_bound]

There is a science fiction story about this called
“The Ice People by Rene Barjavel”
http://en.wikipedia.org/wiki/The_Ice_People_%28Barjavel_novel%29

French expedition in Antarctica reveals the ruins of a 900,000 years old civilization.

[PIF]

If each civilization averaged 6000 years then there could have been over 80 of them in that 500,00 year time frame - all of which could have been scoured out of existence by the Ice and the resulting massive floods beginning around 12,000 years ago.

Then there is circumstantial evidence that there may have been some form of hominid civilization millions of years before the Pleistocene (things reportedly found in coal lumps but now lost). Even the very early Earth (3.2 billion YA) was habitable ... contrary to popular science and opinion.

[SunkenCiv]

The conventional view of civilization, well, historical times, is that it goes back about 5000 years (cuneiform writing), and that agriculture goes back about twice or three times that; the latter is only three percent of this 500K figure. IOW, there’s plenty of room there. During a half million years there’s plenty of time for space debris to arrive in inconvenient places.