While the Cerutti Mastodon claim may be new to most of us because of the recent Letter to Nature (Holen et al 2017), it has in fact been making the rounds for about 20 years. It is part of a much deeper current of advocacy for the interglacial presence of early humans in the San Diego area, which I will call the San Diego School.

The Mastodon site which Holen et al (2017) claim as evidence of human occupation in Southern California 130 000 years ago was discovered in 1992 as part of the State Route 54 expansion project of the California Department of Transportation. The find is mentioned in the LA Times of November 26th 1992 and given a potential age of 10kya to 120kya, but no archaeological remains are cited. The paleontological mitigation report for that project was submitted three years later (Deméré et al 1995). The San Diego Natural History Museum’s timeline of the discovery shows a 13 year gap between 1995, when the original report was submitted, and 2008, when the Holens become involved in the story. The story is in fact quite continuous.

First phase: The Cerutti Mastodon and the San Diego School in the academic early Americas literature

The original report itself does not mention archaeological finds, although it is written in a way that strongly suggests that the authors suspect human presence at the Mastodon site. The language is carefully descriptive, although highly suggestive, and the excavation diagrams are much archaeological than paleontological in flavour.

Within a year, George F. Carter (1996:108), a hyperdiffusionist, San Diego School pioneer, and a long-time leading advocate of the human presence in the last interglacial in the San Diego area, cites Richard Cerutti’s field notes and photos in support of his contention. He references notes on a “mammoth site”, but the timing and reported location (“Oceanside”) argue strongly that he is referring to what we now call the Cerutti Mastodon site.

Carter, by then a Distinguished Professor of Geography at Texas A&M, had been publishing on the interglacial archaeology of the San Diego area since the 1950s and had worked early on at the San Diego Museum of Man. Carter focused mainly on the presence of stone tools in the interglacial deposits of the area. He summarized his claims in Pleistocene Man at San Diego (Carter 1957).

The book’s reception was varied. Malcom Farmer and Earl H Swanson (1958:590) state that “The future may show [Carter] to be wrong in some details, but his thesis of the antiquity of Man in the Americas now seems unquestionable”.  Alex Krieger (1958), on the other hand, in a long, detailed and effective review in American Anthropologist writes that “The discussion of artifacts (pp. 321-346) is replete with confident statements about a ‘fixed pattern’ of fracturing which can only have resulted from human intelligence, with force applied by the human arm” (:976). He goes on to critique these statements in fundamentally the same way we do more than half a century later, namely that there are simpler, natural geological explanation for the evidence cited, and these are supported by experimental studies. In the absence of other lines of evidence, the natural explanations must be privileged until they can be shown to be inadequate. In other words, rightly in my view, he considers this an American version of the eolith debate.

In Holen et al (2017) the language is carefully if grudgingly softened to “consistent with” rather than “can only have been”, but the implication is the same. Incidentally, the merely “consistent with” approach makes it even more astonishing that the paper was published in Nature as a significant contribution. After all, lots of processes in the world are consistent with lots of sets of observable data. The trick in science is to demonstrate that there is actually a relationship.

Second Phase: The Cerutti Mastodon in popular and fringe archaeology

By 2005, what is variously known as the National City Mastodon, the State Route 54 Mastodon, or the CalTrans Mastodon reappears, but this time on popular archaeology and Christian fundamentalist websites, often with a link to a PDF of the original report (Deméré et al 1995). The claim is that it shows human occupation in California between 335kya and 350kya, which is much older than the Cerutti Mastodon claim of 2017. This second wave of interest seems to originate in a commentary by author Michael Cremo (California Dreaming: The State Highway 54 Mastodon Blues), originally published in 2005 in the ancient mysteries magazine Atlantis Rising and reprinted in a 2010 collection of essays. In the essay, Cremo claims to have discussed interglacial human occupation of the San Diego area with Richard Cerutti as part of the research for his Forbidden Archaeology (1993), although the text makes it clear that these discussions took place before the discovery of the National City Mastodon.

By 2007, the National City Mastodon is a fixture of online discussions of early humans in North America and is routinely claimed to be evidence occupation at 350kya.  That year, it is an important point in Christopher Hardaker’s (2007) The First Americans: The Suppressed Story of the People Discovered the New World, in which Cerutti is thanked in acknowledgements. In the years that follow and until recently, the National City Mastodon continues to be sporadically cited as evidence of early human occupation of the Americas, often accompanied by excerpts of the original Caltrans report.

Third Phase: The Cerutti Mastodon in the mass media

In late April 2017, the Cerutti Mastodon Letter to Nature introduces, seemingly out of the blue and after a long gestation, the find and its claim of interglacial human occupation of North America. The article is very widely covered, and surprisingly uncritically. It is no surprise in fact that this development comes out of the San Diego area with its long history of research on this question. What is surprising is that despites its obvious roots, the Nature paper makes no reference at all to this long history and is not contextualized with reference to the evidence previously presented in an archaeological tradition that goes back at least to the 1950s and probably earlier. Other than a quite technical reference to C. Vance Haynes (1969), there is no discussion at all of the problem of the peopling of the Americas in the article itself. Supplementary materials section 9 does give a bit of a discussion on possible early arrival scenarios, but with no reference to any of the sites claimed by the San Diego School (Texas Street, Callico Hills, etc), or any other evidence that requires us to entertain these scenarios. Yet if one accepts the Cerutti Mastodon site as archaeological, then one would have to accept those as well.

I need to make it very clear that by tracing this history and by mentioning contact between the players and various fringe theorists, I am not trying to imply guilt by association for Richard Cerutti, Tom Deméré, the Holens, or anyone else. I engage in frequent dialogue with fringe theorists, both academic and popular. I have been known, for example, to give the occasional (or actually pretty regular) Sasquatch lecture and to correspond and even work with various people interested in pre-Columbian trans-atlantic contact. I think it is part of our role as educators to give them our points of view and to try, in good faith, to understand and comment their ideas. What they do with our words afterward is not up to us. But I do think it is important to properly contextualize the Cerutti Mastodon claim, and I believe it should have been done, however briefly, in the original article.


Carter GF 1996. Early Man at San Diego : A geomorphic-archaeological view, Proceedings of the Society for California Archaeology 9:104-112.

Carter GF 1957. Pleistocene Man at San Diego, Baltimore: Johns Hopkins Press.

Cremo M 2005. California Dreaming: The State Highway 54 Mastodon Blues, Atlantis Rising.

Cremo M and RL Thompson 1993. Forbidden Archaeology.

Deméré TA, RA Cerutti, CP Majors 1995. State Route 54 Paleontological Mitigation Program – Final Report. Prepared for Caltrans, District 11.

Hardaker C 2007. The First Americans: The Suppressed Story of the People Discovered the New World, The Career Press, Inc.

Haynes CV 1969. The earliest Americans. Science 166:709–715.

Holen et al 2017. A 130,000-year-old archaeological site in southern California, USA, Nature 544:479-483.

Krieger AD 1958. Review of Pleistocene Man in San Diego, American Anthropologist 60:974-978.

Swanson EH and MF Farmer 1958. Review of Pleistocene Man at San Diego, Geographical Review 48:588-590.


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