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America was one of the last places humans colonised, with Homo sapiens only arriving there ~15,000-years-ago. However, in 2017 archaeologists found something that seemed to turn this on its head. Whilst supervising highway construction in California, they found the “Cerutti Mastodon site”1.

This collection of bones and tools appeared to show signs of human activity. The twist: it’s actually 130,000-years-old1!

Note how the arrival of humans in America is a little bit less than “130,000 BC”

Obviously, this threatened to shake up the history of humanity; making international news in the process. Crucially, it pushes back the occupation of America before we left Africa. So, if true, this would mean the first people in America weren’t just early, they weren’t even our species!

But the “if true” is a big sticking point. Since these findings were first published, archaeologists have been re-evaluating the site. Sadly for anyone looking to rewrite human history, their findings suggest the Cerutti Mastodon site has a much more mundane origin2.

The Cerutti Mastodon site

The discovery that’s causing all this fuss is a 50 square metre area near State Route 54 in San Diego. This nondescript spot was having a new sound barrier installed, until supervising archaeologists spotted something in the ground. The resulting excavations led to the discovery of more than 300 mastodon bone fragments, earning the locale the name “Cerutti Mastodon Site”. Or the less memorable, SDNHM locality 37671.

Bones and rocks in the ground in California

Crucially, the bones look like they’ve been hit with rocks. Meanwhile, rocks found at the site appear to have been used to hit bones. This was confirmed through experimental archaeology. Researchers hit elephant bones with rocks, documenting the resulting damage. It turns out it was very similar to what was seen at the Cerutti Mastodon site1.

Archaeologists smashing elephant bones to see what it looks like. Who said archaeology wasn’t fun.

This is classic evidence of hominin activity as we’re the only group that butchers meat with tools. As such, it wouldn’t be a big deal. That is until they carried out Th/U dating of the Mastodon fragments, revealing them to be 130,000 years old1.

Which, as I said earlier, is kind of a big deal for a site in California. In fact, no other equally ancient activity has been found. As such, all the evidence for early first Americans rests on these bones and rocks.

Initial debate over Cerutti Mastodon

As with any brand new discovery that threatens to re-write the textbooks, many were skeptical. After all, printing up new books is a hassle people don’t want to have to deal with. This prompted a flurry of back and forth, as scientists argued over the site.

  • Some wondered if the ancient dates were reliable3 but the original authors had an expert in the technique back-up their findings4.
  • Others asked where all the other evidence of these alleged early humans in America was3,5. The original authors contended the absence of evidence is not evidence of absence4.
  • Yet others pointed out that all of these finds were made at a construction site. Can we be sure heavy machinery wasn’t responsible for the damage3,5?
Although the discoverers conducted experiments with stone tools to see if they made comparable damage to bone, no control samples were done with the sort of machinery used at the site1.

This sort of back and forth went on for a little while. Whilst the discoverers of the site could respond to many of the points made, there was enough skepticism that most researchers were unconvinced. The lack of archaeological context, in particular, was a sticking point for many.

After all, by 130,000 years ago hominins had a complex culture, including early signs of art. In Africa, they’ve left behind literally trillions of stone artefacts. Yet despite all of this complex culture, the only trace these first Americans left were a handful of hammers in a Californian ditch. No other bones or tools, genetic traces in subsequent populations, or cool paintings in any caves.

A new challenger approaches

And that’s where the site sat for a while. There were enough reasons to be skeptical that most didn’t take it seriously, but it couldn’t be ruled out entirely. Enter Patrick Ferrell, who looked at the site from a different perspective: civil engineering.

He produced plans of the site, combining the records of California’s Department of transportation with photos of the Cerutti Mastodon site as it was being excavated. These revealed it was located near a drainage system being dug, and dump trucks carrying away the excavated material would drive right over the locale2.

The plan of the dump truck route and drainage ditch overlain on a map of the site

Ultimately, hundreds of laden dump trucks would have driven right over the site, which was only protected by 30 cm of pliable earth. This pressure would have driven cobbles in the earth into the underlying bones, breaking them both in a manner that might look intentional. In reality, it’s just what happens when a bunch of lorries drive over some fossils2.

So, after a few years of research, it seems the Cerutti Mastodon site can be finally put to bed. The real culprit for the first “humans” in America was just modern humans driving heavy machinery. Which is sort of what I guessed when the finds were first announced.


  1. Holen, S.R., Deméré, T.A., Fisher, D.C., Fullagar, R., Paces, J.B., Jefferson, G.T., Beeton, J.M., Cerutti, R.A., Rountrey, A.N., Vescera, L. and Holen, K.A., 2017. A 130,000-year-old archaeological site in southern California, USA. Nature544(7651), pp.479-483.
  2. Ferrell, P.M., 2019. The Cerutti Mastodon Site Reinterpreted with Reference to Freeway Construction Plans and Methods. PaleoAmerica, pp.1-7.
  3. Haynes, G., 2017. The Cerutti Mastodon. PaleoAmerica3(3), pp.196-199.
  4. Holen, S.R., Deméré, T.A., Fisher, D.C., Fullagar, R., Paces, J.B., Jefferson, G.T., Beeton, J.M., Rountrey, A.N. and Holen, K.A., 2018. Broken bones and hammerstones at the Cerutti Mastodon site: a reply to Haynes. PaleoAmerica4(1), pp.8-11.
  5. Braje, T.J., Dillehay, T.D., Erlandson, J.M., Fitzpatrick, S.M., Grayson, D.K., Holliday, V.T., Kelly, R.L., Klein, R.G., Meltzer, D.J. and Rick, T.C., 2017. Were Hominins in California∼ 130,000 Years Ago?. PaleoAmerica3(3), pp.200-202.
  6. Ferraro, J.V., Binetti, K.M., Wiest, L.A., Esker, D., Baker, L.E. and Forman, S.L., 2018. Contesting early archaeology in California. Nature554(7691), p.E1.

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clayton · 20th October 2017 at 7:04 am

Bummer dude! I had high hopes of high strangeness! Oh well, I think there is still a little something odd there, in that something still may have used those stones to break those bones, even though there are no tell-tale signs that we have always used in the past to determine hominin activity. And I wouldn’t think it strange that some circumstance that we have no idea about could dictate that some hominin (Modern or Neanderthal or Denisovan or whatever the next one they find will named)of 130,000 yrs ago would stoop to using the most brute primitive, the most ancient technology in the hominin repertoire, in order to survive. And could it not be the random remnant of activity from some tiny band of humanity who arrived somehow onto the great Continent, whose activities barely left a mark? The last survivors of an earlier wave or pulse of migration, perhaps largely by boat? Who knows for sure? There, I feel better already! And thanks for the heads-up, Adam!

    Adam Benton · 20th October 2017 at 11:00 am

    Like I say, further findings could force re-evaluations of this idea. But they’ve had more than 20 years for those further findings to come forward, and we’ve heard nothing.

GL Quinn · 22nd October 2017 at 1:58 pm

I agree, absence of proof is not proof of absence, however unlikely it may seem. What is likely, though is that the actual very first individuals that crossed into the americas wether by foot or by boat left an extremely minuscule physical impression on the land. This impression in relation to the massive amount of land encompassing the search area leaves an infinitesimally small chance that it will ever be found, and that is if natural processes have not permanently erased the evidence already.

    Adam Benton · 23rd October 2017 at 11:37 am

    Africa is even bigger, yet we’ve still found several sites from this time period. I think it’s likely, if there was an occupation in the Americas, something would have turned up. But you’re right, we can’t really rule it out for sure. There’s always the chance for more data to change our conclusions, and that’s why I end with some caveats to my dismissal. But I still think it’s unlikely.

      Bradford Orin Riney · 26th March 2018 at 2:08 am

      Something did turn up, it’s preserved for you to examine at the SDNHM. Africa is the hotbed of human evolution and only a few 130,000 year old sites? That’s not a good argument against the Cerutti Mastodon site.

        Adam Benton · 31st March 2018 at 11:42 am

        Another site was found? That’s fascinating, I couldn’t find anything when I was searching. You’ll have to provide a link.

    Bradford Orin Riney · 26th March 2018 at 2:12 am

    Very good and they probably became extinct here in NA leaving nothing as evidence until the next global warming event.

Greg Little · 22nd October 2017 at 5:49 pm

I assume that you reject the dating of Meadowcroft, Cactus Hill, Topper, and other sites in both North and South America that predate the 15,000-year-ago timeframe for the First Americans you cite? Do you also reject the geneticists’ studies for the older dates for mtDNA entry into the Americas?

    Adam Benton · 23rd October 2017 at 11:28 am

    Whether I do or not is somewhat irrelevant here. There may be a case to be made for these early sites, but at most they’re going to push back the habitation of the Americas by a few thousand years This site purports to push it back by several orders of magnitude more. We can disagree over the 15,000 date whilst also agreeing its probably closer to that date than 130,000.

    RaceRealist · 28th October 2017 at 12:06 am

    Do you also reject the geneticists’ studies for the older dates for mtDNA entry into the Americas?

    Do you have a citation?

      Adam Benton · 31st October 2017 at 11:28 am

      I’m not that commenter, but I think he’s referring to the earlier discussions of mtDNA from the late 90s/early 00s that indicated an earlier migration than the archaeology alone would indicate. It was discussed in several papers over this period, with one of the more notable examples being:
      Bonatto, S.L. and Salzano, F.M., 1997. A single and early migration for the peopling of the Americas supported by mitochondrial DNA sequence data. Proceedings of the National Academy of Sciences, 94(5), pp.1866-1871.

ape man · 22nd October 2017 at 10:32 pm

These findings are real. It would be more far more odd if Homonids never made it to the Americas before twenty thousand years ago.

    Adam Benton · 23rd October 2017 at 11:33 am

    The colonisation of America was hindered by the fact it’s quite hard to get to. The Beringia landbridge used to spread into the Americas was underwater for most of Homo sapiens history. The longest it was exposed coincides with the accepted age of the earliest American populations. People seem to have spread along it when they had the chance, the chance was just stolen from them by the sea for a good chunk of prehistory.

      Figure Stones · 21st April 2019 at 9:22 pm

      But the monkeys made it to the Americas over 20MYA.

        Adam Benton · 8th May 2019 at 1:53 pm

        Probably closer to twice that, back when sea levels were lower, continents were closer, and there may have been more islands in the Atlantic

RaceRealist · 28th October 2017 at 12:08 am

What do you think of this article on the possibilities of Homo erectus making it to America?

Dreier, Frederick G., (1986). Homo Erectus in America: Possibilities and problems. Lambda Alpha Journal of Man, v.17, no.1-2, 1985-1986. Citing: Gifford, E.W., (1926). California Anthropometry. University of California Publications in Archaeology and Ethnology.22:217-390

I speculated that it could have been erectus in America with that finding, but now it doesn’t seem like it. The paper above is still interesting however.

    Adam Benton · 31st October 2017 at 11:36 am

    I mean, that paper is interesting as something of a time capsule. It’s chronologies are amusingly outdated and it’s fully embedded in the now disproven multiregional model of modern human origins; to the point it has H. erectus transitioning into H. sapiens in 5,000 years to make its chronology work. Compared to the work Greg was talking about in other comments (which happened only a decade later) it really hammers home how drastically things can change in palaeoanthropology.

Brett Martin · 6th November 2017 at 1:51 pm

Hi Adam are you also dismissing, discrediting, ignoring the finds from Hueyatlaco by Virginia McIntyre and her team? Dates of 250,000 were obtained from tehpra dating.

I also notice your still stuck with you out of Africa falsities, Are you also dismissing, discrediting ignoring the recent German finds of what are believed to be Australopithecus Teeth dating to almost 10 million years old?

Yeah, I told ya so….

    Adam Benton · 9th November 2017 at 11:59 am

    Yes. Hueyatlaco has incredibly complex stratigraphy that makes dating very difficult. Numerous studies have found this problem, notably discovering that the layers date out of order (i.e. layers closer to the surface, which should be more recent, dating older than their underlying strata). It’s taken decades of research, but these issues are finally being worked around and real dates for the site in question are coming out. Spoiler, they’re not 250,000 years old.

    The German teeth are harder to examine as it’s a newer find without the decades of follow-up into it. However, it is worth noting that not everyone is even convinced that they’re ape teeth, let alone Australopithecus teeth.

Bradford Orin Riney · 26th March 2018 at 1:36 am

As a proud filthy monkey who actually worked on the site I can say taphonomically this site is not natural. I’ve found and excavated with my Buds, probably a hundred large mammal sites from the Eocene to the Pleistocene, many of them Probiscidean sites and this particular one is totally anomalous, DUDE! Refits of stone and bone everywhere, most encrusted with pedogenic carbonate in an UNDISTURBED pristine context. Micro flakes of both stone and bone through out the site. NO HYDRAULIC SORTING what so ever such as Noah’s Flood! We have a vertically oriented tusk next a horizontal tusk. The vertical tusk extended 70cms below the site, exhibiting sediment drag along the south side as it was punched through the various beds and is also encrusted with pedogenic carbonate. NO machine breakeage or mechanical crushing with the exception of material at the extreme north east edge where the excavator bucket teeth came in contact with the site. Geologically the Cerutti Mastodon lies within the upper 20′ of a Pleistocene valley fill related to the MIS 5e sea level rise 140,000 to 123,000 years ago. Coastal valleys fill in with sediment when the sea levels rise producing these valley fills. The radiometric dating fits perfectly the geology of the place. Elementary my good people. Finally one needs to come to the SDNHM and actually study for themselves the material before making the same old boring excuses as to why hominins couldn’t and Nature did.

    Adam Benton · 31st March 2018 at 11:54 am

    That does certainly help rule out machine causes, I’ll have to update the post accordingly at some point. Nevertheless, I’m not sure how many other alternative factors can be ruled out by this.

      Bradford Orin Riney · 27th April 2018 at 11:06 pm

      Visit Nat Talk ” An evening with the Cerutti Mastodon Scientists” a 1.5 hour video doing a way better job of presenting the evidence than I can, me being just a simple filthy monkey.

        Adam Benton · 30th April 2018 at 11:50 am

        Thanks for the tip, I’ll check it out.

Bradford Orin Riney · 27th April 2018 at 10:49 pm

Jump on a plane and check out the material.

Bradford Orin Riney · 4th May 2019 at 6:28 am

Ferrell’s article is a rediculous attempt at forensics 25 years after the fact using construction plans to create an exteremely innacurate story of how the Cerutti Mastodon was found. Tom Demere one of the authors in the Nature Letter contacted Ferrell about this. Ferrell later apologized for not contacting us at the SDNHM before he wrote the article. There were no 5 ton dump trucks ever at the site running it over as stated by Ferrell or any other heavy equipment clanking around supposedly smashing thing up. We’ve been monitoring construction sites both major and minor since 1981. We know what heavy machinery does to fossil bone. The vertical tusk would have been completely destroyed as well as the other material in Ferrell’s scenario! The site was preserved undisturbed under well consolidated Pleistocene sediments. Tom would have graciously shown Ferrell the extensive notes, still pictures and video taken during the 5 months of excavation showing all of this. Journalism at it’s worst gobbled up by Archaeologists desperate to save their paradigm, which still is valid by the way, no need for them to panic. The Cerutti Mastodon Site is a true Old World style Paleolithic archaeological site. Most American Archaeologists have no training here. We just simply added Chapter One to the story.

    Adam Benton · 8th May 2019 at 1:58 pm

    I look forward to the response then. Hopefully, I’ll get another blog out of it.

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