In evolution studies have shown that certain features recur independently of each other. For instance flight in animals has evolved in birds but there are also mammals that have developed this ability not to mention insects, probably the first of all the species to use flight as a means of getting around.
Crabs have also evolved seperatley oddly enough as well as other things like slime as a useful tool in aiding in the ability to move around in the world and survive long enough to reproduce and thus evolve.
So, what has all of this got to do with ancient civilisations I hear you say.
Well, it all has to do with the Silurian Hypothesis, a paper by Adam Frank and Gavin A.Schmidt which asks whether it would be possible to detect an industrial civilisation in the geological record. Something which most of us would assume to be relatively easy since any civilisation that was evolved enough to be building technologically advanced machines would have left traces of their existence somewhere.
But no.
If the human race was wiped out tomorrow it is unlikely that there would be any trace of us within a few million years. If you don’t believe that then just think about this for a minute. Dinosaurs were around for over a hundred million years. Therefore there were probably hundreds of millions if not billions of each species yet we have only found a handful of some of them, the rest are lost forever. it is postulated that we have found one fossil per 10,000 years. Modern technology has only existed a few hundred years so the chance of anything being left behind for somebody to find in a few million years would be extremely remote.
Looking at the Earth’s temperature over history could give us a clue. The anthropocene era is the geological epoch dating from the commencement of significant human impact on the Earth’s geological ecosystems and similar hyperthermal activity can be seen 55 million years ago when the Earth’s temperature rose by 5-8 degrees celsius (9-14 degrees Farenheit). This could indicate an era of increased carbon fuel activity hinting at a technological advancement of a civilisation of some kind. It could also indicate an asteroid collision or massive volcanic activity but there is no evidence to support any of these hypotheses.
The possibility of ancient civilisations is surprisingly hard to find in sci-fi films and novels and is not something that has a lot of support. That is why it is so interesting to look at the evidence and realise that although unlikely it is still a possibility.