What if we aren't the first technological civilization on Earth? We’re almost certainly the first technological civilization on Earth. But what if we’re not? We are. Although how sure are we ...

Recent advances in ancient DNA analysis have sparked intriguing discussions about the possibility of non-human entities once ...

They address a number of misconceptions about studying the past, and present several ways we might test for a pre-human Earth civilization. One of the first things they discuss is the fossil record.