Spedicato's interests also concern ancient history, especially with respect to catastrophic events of extraterrestrial nature, where he has published papers related to Atlantis, Exodus and the Tunguska-type impacts of 1178 AD over the Pacific. He has also studied problems in biblical and other ancient texts, dealing e.g. with the geography of Eden and Gilgamesh's travels, the empire of Solomon, the origin of the Etruscans within the theory of Alinei who has shown their language to be ancient Hungarian.