So what about the human race? Well I stopped worrying about pollution and co2 a long time ago as I believe it makes no difference at all. The earth will survive anything we humans do and just carry on until the sun explodes.
Indeedy. The planet will be just fine. We might not be, but something will replace us.
The bottom line is that we are only passing through and going through a new beginning every so many million years so who's to say there wasn't another civilisition of us half a million years ago?
There were certainly hominids around, maybe twice as long ago, but not 'us' and not a civilisation - we would have found traces of any buildings, which don't really start appearing until 25,000 years ago depending on what you call a building.
As to historical cycles, there's a wonderful Arthur C Clarke story about a planet with multiple suns, which has permanent daylight until a total eclipse every couple of thousand years. That eclipse reveals that they live in the centre of a globular cluster, a sight so awesome that religious fanatics destroy everything and they have to start again. And again. I can't remember the title of it now, but it's worth a read ...
