Michael Cremo's book Forbidden Archeology, coauthored with Richard Thompson, caused shock waves in the world of science, It exposed evidence for a human presence on this planet going much further back in time than the current dominant consensus in the world of science allows.

In Extreme Human Antiquity, Cremo builds on the foundation of Forbidden Archeology, introducing explosive new cases from all phases of archeological research, from the nineteenth century to the present. Drawing on his knowledge of the history and philosophy of science, he documents how evidence for extreme human antiquity has been subjected to a process of knowledge filtration, by which this evidence is ignored, forgotten, set aside, or dismissed on flimsy grounds.

Evidence for extreme human antiquity includes human bones, human footprints, and human artifacts. Cremo's understanding of what counts as human includes discoveries that have previously been attributed to Neanderthals and other hominin species. Cremo presents for each case the pros and cons for taking it as evidence for extreme human antiquity and lets readers make their own decision.