Wikipedia says:

Hueyatlaco is an archeological site in Valsequillo, Mexico. After excavations in the 1960s, the site became notorious due to geochronologists' analyses that indicated human habitation at Hueyatlaco was dated to ca. 250,000 years before the present. These controversial findings are orders of magnitude older than the scientific consensus for habitation of the New World (which generally traces widespread human migration to the New World to 13,000 to 16,000 ybp). The findings at Hueyatlaco have mostly been repudiated by the larger scientific community, and have seen only occasional discussion in the literature

There seems to be persistent claims, based on radioactive dating, and some claims of a cover-up, etc.

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    Your Wikipedia link gives a summary of the evidence, and the position of the larger scientific community. What sort of information would you expect in an answer that isn't included here? I am trying to avoid just regurgitating the links from the existing Wikipedia entry.
    – Oddthinking
    May 19 '13 at 9:07

I'll try to summarize why the evidence, in this case and other similar ones, is considered not conclusive.

The scientific community agrees on America being populated as late as 13-17k years ago, and as early as 40k:

The time range of 40,000–16,500 years ago is a hot topic of debate and probably will remain so for years to come. The few agreements achieved to date include:

  • the origin from Central Asia
  • widespread habitation of the Americas during the end of the last glacial period, or more specifically what is known as the late glacial maximum, around 16,000–13,000 years before present (One of many sources: Did First Americans Arrive By Land and Sea?)

This is why those affirming Hueyatlaco is older than that (link to most comprehensive publication about the subject) are generally thought to be dealing with contaminated evidence. The biggest defender of this theory is Virginia Steen-McIntyre, who was a graduate in the 1966 excavations.

The way these sites' antiquity is measured is usually 'indirect', meaning that if stone tools are found in a certain stratum, it's the stratum that gets dated, not the tools. The stratum where stone tools were found in Hueyatlaco was dated as older than 35,000 ybp by radiocarbon (animal or plant remains - only good for 'newer' datings) and 260,000 ybp, ± 60,000 years by uranium dating.

The discussion around the dates has to do with how trustworthy an indirect measurement like this is, when the value falls so off what's generally agreed on. You can't date the tool itself because stones don't give any information about time of human manipulation (unless you have a known classification of technologies or styles).

The problem is that strata is not necessarily something static. Steambeds and other natural phenomena, as well as animals digging caves, for example, can erode and change their structure. There is a number of documented reasons why you can end up with newer artefacts on older layers (I worked on a cave site that was almost impossible to date this way, because there were rat skeletons in every stratum, showing these animals had dug caves and moved all the materials around). The area around Hueyatlaco is subject to flooding.

So, unless you have tools can be dated by themselves (made of organic materials, for example), there is always space for speculation of contamination. The rocks in that strata are that old, yes, but the tools on it seemingly are not. Affirming they are would be debunking what we know about Homo sapiens.

Because the current paradigm states that the first populations for that part of the continent moved in about 13k to 40k years ago, these datings are considered to be not trustworthy.

Some more references regarding archaeological contamination and the relationship between archaeology and geology:


It appears to be more complicated than simple strata contamination, and there does seem to be more of a problem with politics than most people forwarding answers suggest. Does Hueyatlaco show, as the question asks? In many private professional opinions, yes, but certainly not conclusively, especially not in consensus.


If the timeline is correct, frankly it comes down to less than forthright accounting and bias. The main on site proponent of this is Virginia Steen-McIntyre, but quite a few others in the field.

There does seem to be a lot of politics involved in any site considered pre Clovis (13k ybp), and at the Monte Verde site Tom Dillehay flew relevant colleagues down to Chile to monitor progress in avoiding just this aspect (which generally worked with one exception). In the 1960's when excavated, Hueyatlaco was under particularly intense scrutiny when the dates came out.

https://en.wikipedia.org/wiki/Paulette_Steeves included about 120 sites of the Pleistocene in the 2021 book, The Indigenous Paleolithic of the Western Hemisphere, half of them before the 18,000 year mark and 10 or so beyond 50,000 years ago with only two being in South America (Toca da Esperanca and Pedra Furada). Four of those were initially excavated by the archaeologist Cynthia Irwin-Williams - Wikipedia and are closely bunched near Valsequillo Reservoir, Hueyatlaco being one of those. Numerous later sites are also on said reservoir area, which mirrored a Pleistocene lake.

Steeves points out in pg 122 that one of Irwin-Williams' objections to earlier dates was the lack of extensive knowledge of tools and H. Sapiens in 1969 compared to that existing presently in later decades. While admitting the great deal of controversy in the dating of Valsequillo Reservoir excavations, the location undoubtedly had extensive human/animal interactions during the Pleistocene and the sites and area are worthy of further research. The Presa Manuel Avila Camacho dam formed the lake in 1946.

Many of the sites on this list have been discussed by archaeologists as problematic based on one or more arguments. However, the majority of the sites have not benefited for a published critique based on first-hand knowledge, site visits, or collection studies. Tom Dillehay (2000) argued that many discussion which dismissed pre-Clovis sites as illegitimate were often based on invented mistakes.

https://www.nature.com/articles/d41586-020-02190-y 30,000 year ago cave habitat of man in Mexico seems to be generally accepted so far.

https://www.nature.com/articles/nature22065 Hypothesis:

There are a few others, and the trend seems to indicate that isolated populations of hominids did make it over the Beringia region in favorable times.

http://pleistocenecoalition.com/newsletter/may-june2011.pdf page 11 'diatoms'

I am a layman, and have read the dealings with excavation from both points of reference. It has been written that the tools found were highly anomalous to the claimed 250k ybp date. This in itself is not unheard of, and taxonomic records are often irregular.

http://pleistocenecoalition.com/newsletter/january-february2012.pdf el horno item.

The Xalnene Tuff Footprints in then general area, pretty well confirmed to be 1.3 million years ago.

The below research paper logic seems skewed in conclusion, that the date is too far out of normal thinking -- as many animals took the over Beringia journey in either direction even as late as the often chilly early Pleistocene:

"If the [ichnofossil marks] were of human origin, then they would probably be early Homo erectus ... This is unlikely based upon the known geographic distribution of these early hominids (Anton and Swisher, 2004) and the genetic and archaeological evidence for the peopling of the Americas."

Well now, that is opinion. The taphonomic record is by its very nature extremely tenuous for migration paths over hostile territory, which all of Beringia was for such a stenobiont as H. Erectus. As people such as Stephan Gould have pointed out, even the most heavy of human fossil records tend to be on the order of 1:1,000,000, sometimes 1:100,000,000 or less. For a cul-de-sac isolated population, especially a recurring extincted group (as Greenland was), both the fossil record and any remaining genetic evidence would not necessarily be a given.

It is known that stone tools varied widely in this period (e.g. https://www.thoughtco.com/acheulean-handaxe-first-tool-171238 was used for about 1.5 million years in one form or another and until about the early Holocene.) In those days, groups had widely differing levels, and much more like chimpanzees in that groups did not share technology as much as traditions inside the group. https://www.jstor.org/stable/3630525

A population that managed to get over the Beringia strait or via lowered sea levels had some significant hurdles to overcome, much more so than camels or horses which went the opposite direction in much warmer times and a possible raised strait. The odds of such a group would be greatly improved with forefront technological advancements.

In recent hunter/gatherer groups are about 50% of executions are top alpha men who become too assertive, including bullying, which tends to offend the egalitarian natures of the group. These people are prime candidates to found a dynamic, exploratory group, such as from Siberian Denisova Cave, which has been dated via proteins to 217k ybp, and occasional ranging up to the Arctic circle by Denisovans or Neanderthals is highly likely.

Hominid rafting dispersals would be much less likely, and require far less technology, so this potential would not apply.

Like a few Greenland populations, these hypothetical hominid populations may well have lasted only for a short time, yet the widely dispersed in space and time of the 50k years or older sites suggest otherwise. More likely they would have lasted tens of thousands of years, an isolated, genetically poor relict population but not a 'waif biota' as such (Alfred Wallace's term). In any case, we are seeing a lot of evidence of such, not unlike that in early years of Neanderthal or other species of finds.



There was a skull found very near the Valsequillo Reservoir, called the Dorenberg Skull, but like Mikulov_Castle Cro Magnon (Aurignacian) artifacts and skeleton, along with various East Asian hominid remains, it was almost entirely destroyed in WWII or by other losses. Only a few shavings had been taken and stored in other institutions out of the country.


In short, there is a great indications that there were populations, and if science is to progress, sites should be given their due, not almost complete ignored. The Cerutti Mastodon from 1992 til 2010/2017 is a case in point, and PCN was apparently fundamental in bringing that out.

Hueyatlaco is not dead, nor is it really discredited, although at a conference from hell it was allocated a tiny, improper room across campus, a unique treatment. However, what we need is more information from other sites, which funds should be forth coming as they are discovered. More importantly, these should be allowed for rather than a mysterious date of about 15,000 y.a.

The Cerutti site was nearly not carefully examined, and that was in America. As it was, the National Geographic grant was very important in allowing a proper examination, and that organization does not lay out serious money for trash. Mastodon sites are common. Ones with obvious signs of bone extraction via hominid methods are not. The age was always thought of as before 40,000, with indications of much earlier times. Recent advances allowed a defining of this date to roughly 130,700 years +- 9,400. The same may happen for Hueyatlaco.

Additionally, relict small populations typically eventually die off from capacity changes (e.g. climate), inbreeding, lack of Allee effect, or other, and are slow to regenerate when not becoming past tense. Were it not hominids referred to, and the attending politics, no one would bat an eyelash, and there would be no controversy.

What we do not need are nit pickers, or in the case of Hueyatlaco, apparently a high government official that hated women and yet another obstacle to partially overcome (according to Virginia Steen-McIntyre's account). Or that apparently Cerutti Mastodon site was not the only find with hominid evidence in San Diego County. George Miller (Imperial Valley College Museum) apparently said in a personal communication that his 1986 Anza Borrego excavation had similar, also dated to about 130 k.a.

Or that the also controversial Calico Early Man site (encouraged and steadily supported by Louis Leakey, about 200 miles/300 km drive away from Cerutti) yielded a bone along with the alleged stone tools. 4 decades afterwards it became necessary to give lawsuit to see if it is human, by the Native American Graves Protection and Repatriation Act. So far no legal resolution it seems, years into the situation. A reverse was the Kennewick Man, 9 k.a., which had the Smithsonian Institute sue to date and examine the bones. The remote site was intentionally covered over by Army Corps of Engineer bulldozer within days of discovery, despite being on an eroding Columbia and no construction going on beforehand. Yes, it could be said there is a lot of politics and professional territorial squabbling going on.

Besides finding more American sites of the Western Hemisphere, one possiblity is to also roll back the dates in Siberia (currently one site in The Bunge--Toll site is 45 ka, remains of a hunted and dismembered wolf by hominids, is only about 1,000 km due West/North/West of Barrow Alaska, listed among 2 other Russian Arctic circle sites of nearly the same time, all very possibly not h. Sapiens -- Pitulko,Science Magazine 2016).

That might be extremely difficult if the population densities were extremely low and only a source population passing through. Also, trebling occupation dates is likely <10x less available for examination from erosion or permafrost, it is guessed.

As far as the interior workings of Hueyatlaco, one might refer to the many PCN articles, although I will locate more independent sources soon of both sides of the controversy. http://pleistocenecoalition.com/#virginia_steen_mcintyre

https://www.worldhistory.biz/prehistory/89374-the-earliest-archaeological-sites-in-middle-america.html is a good overview (IMO) of the general situation as we now have evidence of such, including Hueyatlaco.

"Paleoindian sites in Middle America dating to the earliest time of occupation are scarce, hindered by the fact that population density was low, residence was transitory, and material possessions minimal (Figure 3). Perhaps equally significant, the small number of known sites may be attributed to the relative lack of attention paid to Middle America’s Early Paleoindian prehistory, given the allure of the area’s more spectacular later periods."

At present, the steps of Steen-McIntyre are listed here https://youtu.be/3yo2FluHZUc?t=298

I will be reworking this entry to a more proper format as time allots.

Also see the pdf at "Interim Extension Profile 2004 Hueyatlaco", either by image Google search or by regular Google.

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    Welcome to the site. When you have a chance, please take the tour and see the help center. I hope to see you post again soon.
    – fredsbend
    Jul 20 '20 at 2:18
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    I think there are some interesting points of information here, but it definitely needs tightening up to focus more on the nature of the evidence and less on the commentary about scientific culture. As Keith Morrison says, there is always a higher threshold to cross when challenging a paradigm than when providing details within it, so demonstrating the strength of evidence for this interpretation is going to be key.
    – IMSoP
    Jul 21 '20 at 14:47
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    @Gilmingtom A paper published in Nature is still just one paper, and you haven't even mentioned in this answer what evidence is presented in that paper, and how confident its conclusions are. Your answer still spends all its time discussing the politics (I don't care what room who had at what conference!) and none actually summarising the evidence. Pretty much the only on-topic parts are a handful of links and some references to people and organisations whose relevance to the topic we're left to guess at.
    – IMSoP
    Aug 30 '20 at 8:57
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    @Gilmington No, an encyclopedic entry is precisely what we do not want. This is a Q&A site, and a good answer needs to address the specific question being asked. Some of this wider context might be useful in passing, but your answer needs to concentrate on the evidence that relates directly to the Hueyatlaco site, because that's what this question asks about. Everything you include needs to relate back to that, not be a general essay about scientific debates.
    – IMSoP
    Sep 2 '20 at 15:33
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    Just to reiterate my above comment after your edits today: to improve this answer you need to make it shorter not longer, so that it focuses on the specific question raised. Start with what evidence we have for this specific site, and then summarise why it's controversial but shouldn't be dismissed. Your opinions about the personalities involved, and discussion of other controversies in the same area of research can go on your own blog; they don't belong on this page.
    – IMSoP
    Feb 26 at 13:01

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