What evidence is there of pre-Adamic civilizations?
The idea that there were civilizations on Earth before Adam began among the Christians of England and Europe in the early 1600s. It was an idea that resulted from the discovery of remote tribes who looked "different." The explanation put forward was that these people were survivors of the Genesis Flood and were once part of a great civilization.
Without saying so, the implications were profound. Where did this great civilization come from in the first place? Today, broad hints are being given that the ancient Earth was "seeded" with life from outer space. Adam was thus a descendant of that civilization and chosen by God to be the founder of His people.
Unfortunately, there are Christians who wish to believe all this. Consider: There were eight related people on the Ark, the Genesis Flood was global, and it lasted just over a year. Where does the alleged great civilization live during that time? Supporters of the theory had to argue that the Genesis Flood was, in fact, merely local and the great civilization – or its remains – was on another part of the planet!
As far as Christians are concerned, the Pre-Adamite theory denies that God created the entire universe, including planet Earth, in six days. Thus, it denies the fourth commandment (Exodus 20:11). The theory also denies the creation of Adam and Eve, thus putting both the First Adam and the Last Adam – Jesus – in doubt!
In the last few decades, there have been and still are many influential writers convincing their readers of sophisticated building complexes, usually at the bottom of the sea, and "observatories" such as the one on the Nazca Plains of South America. One of the most influential of these writers who claimed to have personally investigated every site was Erich Von Daniken, author of the bestselling book Chariots of the Gods? He had certainly convinced himself before convincing others, but close inspection of his work showed that it was all speculation, grasping for evidence to support it.
Recommended reading. Pre-Adamic Man, documented essay by Ian Taylor