TheoryUltraterrestrial / cryptoterrestrial hypothesis UTH / CTH

The frame has a long history under different names — John Keel’s “ultraterrestrials,” Mac Tonnies’s posthumously published The Cryptoterrestrials (2010) — but its current academic profile derives from Diana Walsh Pasulka’s American Cosmic: UFOs, Religion, Technology (Oxford University Press, 2019) and Encounters (2023), and from the adjacent work of Garry Nolan at Stanford on material analysis and on what he and Pasulka have called the “phenomenon.”

The contemporary version was given new shape by a June 2024 preprint in the journal Philosophy and Cosmology (Lomas, Case, and Tim Lomas) that mapped four sub-variants: subterranean, undersea, hidden-on-the-surface (an unobserved population in remote regions), and former human (a remnant of an earlier technological civilization). Journalist Tim McMillan, attorney Daniel Sheehan, and physician Brendan Carr have all publicly taken some version of the UTH seriously in interviews and podcasts.

The frame is attractive to several adjacent disciplines: to archaeologists because it does not require interstellar travel; to biologists because it does not require independently-evolved bipedal humanoids; to intelligence analysts because it produces concrete predictions about where to look (deep ocean trenches, subglacial systems, remote highland refugia, uncharted volcanic-vent complexes).

What the UTH predicts: material samples will share Earth’s isotopic signature. Genetic material, if recovered, will share substantial sequence with terrestrial life. The phenomenon will show long historical continuity with human myth and contact accounts. Geographic clustering will correlate with hard-to-access regions — abyssal plains, subglacial lakes, deep cave systems — rather than with the night sky.

Where the UTH differs from neighbors: from the ETH in rejecting an extraterrestrial origin; from the IDH in insisting on physical residence within the Earth system; from the ancient-astronaut hypothesis in not requiring that the population ever came from elsewhere; from the hollow-earth tradition in not requiring any particular geometry of concealment.