Mastodon Site in San Diego Said to Be Earliest Sign of Humans in America, Riling Skeptics

Archaeologists in San Diego are reporting a find that they say will upend our understanding of human history in the Americas. Some experts, however, are greeting their claims with robust skepticism.

The claims stem from a site in San Diego County, along State Route 54, that was found in the early 1990s to contain the scattered remains of an Ice Age mastodon.

A new analysis of those bones concludes that the mastodon was butchered by humans.

But it adds that the the butchering took place at an astonishing time: 130,000 years ago — well more than a hundred millennia before humans are thought to have arrived in North America.

“This discovery is rewriting our understanding of when humans reached the New World,” said Judy Gradwohl, president and CEO of the San Diego Natural History Museum, in a statement to the press.

“The evidence we found at this site indicates that some hominin species was living in North America 115,000 years earlier than previously thought.

A concentration of fossil bone and rock found at the site. The round objects at upper left are the heads of a femur. Mastodon molars are in the lower right next to a large rock and a broken vertebra. Upper left is a rib resting on a rock fragment. (Credit: San Diego Natural History Museum. May not be used without permission.)

“This raises intriguing questions about how these early humans arrived here and who they were.”

The find was reported in the peer-reviewed journal Nature, by a team of 11 archaeologists, paleontologists, geologists, and other specialists, led by Dr. Steve Holen of the South Dakota-based Center for American Paleolithic Research.

The team reported the find after re-researching the objects recovered from the Cerutti Mastodon site, where the fossil of the extinct elephant was first discovered in 1992.

(Read about a related find: “Giant Ice-Age ‘Longhorn Bison’ Unearthed in San Diego“)

Among those objects, the team has reported finding previously unreported evidence of butchering, including spiral-cracked mastodon bones, stones that appear to have been used as tools to break them, and flakes from the tools’ use.

And, while no material at the site was dateable using radiocarbon, the researchers measured levels of uranium and thorium that produced the extraordinary date of 130,000 years.

For some observers, these claims are extravagant enough to require substantially more evidence.

Dr. Jon Erlandson is an anthropologist at the University of Oregon who specializes in researching the earliest inhabitants of North America’s Pacific Coast.

His recent studies have focused on camps and tool-making sites on the Channel Islands that date back as much as 12,000 years, traces of seafaring people who were some of the first occupants of southern California.

(See some of Erlandson’s latest research: “Ancient Seafarers’ Tool Sites, Up to 12,000 Years Old, Discovered on California Island“)

But Erlandson remains unconvinced by the new findings, which to him ring of previous theories that have been debunked.

“There have been similar claims made before, of course, by George Carter and others, for Last Interglacial humans in the San Diego area and the Americas,” Erlandson said, in a statement to Western Digs.

“The authors don’t cite any of these, perhaps because they have been so thoroughly discredited.

“When all the evidence is weighed objectively, I doubt that many archaeologists will be convinced by this case, either.”

For its part, Holen’s team maintains that the evidence deserves a closer look.

Its findings include two main clusters of mastodon bone fragments that bear spiral fractures and shattered teeth, indicating, the team says, that the breaks occurred when the material was still fresh.

Among the broken remains were found five large cobbles that appear to bear patterns of use-wear, and which the team postulates were used to break the bones open to access the calorie-rich marrow.

“The bones and several teeth show clear signs of having been deliberately broken by humans with manual dexterity and experiential knowledge,” said Holen, in the museum’s press statement.

“This breakage pattern has also been observed at mammoth fossil sites in Kansas and Nebraska, where alternative explanations such as geological forces or gnawing by carnivores have been ruled out.”

Dr. Tom Deméré is curator of paleontology at the San Diego Natural History Museum and a co-author of the new study, who also took part in the original 1992 dig of the site.

A close-up view of a spirally fractured mastodon femur bone.
(Credit: Tom Deméré, San Diego Natural History Museum. May not be used without permission.)

He added that the material was found in a stratum of earth that pre-dates the conventionally accepted arrival of modern humans in the Americas — typically estimated between 14,000 and 16,000 years ago.

(See a recent find from this time: “16,000-Year-Old Tools Discovered in Texas, Among the Oldest Found in the West“)

“When we first discovered the site, there was strong physical evidence that placed humans alongside extinct Ice Age megafauna,” he said in the statement.

“This was significant in and of itself and a first in San Diego County.

“Since the original discovery, dating technology has advanced to enable us to confirm with further certainty that early humans were here significantly earlier than commonly accepted.”

That technology involves measuring the amount of uranium in the material and tracking how much of it has decayed into thorium. Given uranium’s steady decay rate, the proportion of the elements can provide an accurate date, said Dr. James Paces, a geologist with the U.S. Geological Survey who took part in the study.

“The distributions of natural uranium and its decay products both within and among these bone specimens show remarkably reliable behavior, allowing us to derive an age that is well within the wheelhouse of the dating system,” Paces said.

This date, it bears mention, contradicts the date that Deméré and Dr. Richard Cerutti — for whom the site is named — obtained when they originally reported the mastodon find in 1995.

After conducting radiometric dating on a sample from one of the animal’s tusks, they initially determined the age to be 300,000 years old.

But other observers question not the dating methodology but the interpretation of the site as one where butchering took place, instead of one where a mastodon died a simple, lonely, and natural death.

“Broken bones and stones alone do not make a credible archaeological site, in my view, especially without a detailed description of their broader geological context,” Erlandson said.

Dr. Torben Rick, director and curator of North American archaeology at the Smithsonian Institution, also expressed his doubts.

(See Rick’s recent research in the area: “11,000-Year-Old Seafaring Indian Sites Discovered on California Island“)

“While I appreciate the discussion of taphonomy, potential stone tool use, and even some of the experimental butchery work, I am not convinced that this site and its contents are archaeological,” he told Western Digs.

“From the photos of the tools, I am not convinced these are the real deal,” he added.

A large cobble found at the site is described by the research team as a possible hammerstone. (Credit: Tom Deméré, San Diego Natural History Museum. May not be used without permission.)

“I also think that there are alternative hypotheses that could explain some of the breakage patterns, even though the authors try to explain many of those away.”

Erlandson, the Oregon anthropologist, raises another concern.

“If there were hominins in California 130,000 years ago, what happened to them for the next 100,000-plus years?” he asks.

This is indeed a vexing question that Holen’s team does not address in its paper.

But in a separate Nature opinion piece, one the paper’s peer reviewers, Dr. Erella Hovers of Hebrew University, offers a modest proposal: The mastodon site, she says, may be evidence of another hominin species — like Homo erectus or Homo denisova — that reached North America before modern humans even migrated out of Africa.

In the end, if there’s any consensus to be found among Holen’s team and the skeptics, it’s that the Cerutti Mastodon site would benefit from further study.

“The key for the future of this site and its purported archaeological finds will be future analyses by independent researchers, especially a larger group of archaeologists,” said Torben Rick, of the Smithsonian.

“If they turn out to stand up to great scrutiny that would be very exciting, but for now I am extremely skeptical about this find.”

Oregon’s Erlandson was more succinct.

“The claims made are extraordinary and the potential implications staggering,” he said.

“If extraordinary claims require extraordinary evidence, I didn’t find it in this paper.”

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  1. B.W. Ash

    This dating is consistent with the findings of Dr. Louis B. Leakey, many years ago. The sites were excavated and dated to be in the 100K plus BCE range. Dr. Leakey was discredited and widely ridiculed by those whose only proof was that, ” people were not in America that early…”

  2. Kimberly McAllister

    I don’t know why it would be so hard to believe that people entered North America so early. We don’t know nearly anything about the past, yet, compared to our brief span of recorded history. And if humans have proved anything, it’s that they have to roam.

  3. Mister Gee

    This excavation site is nearly ten years old, and you would think that time was spent diligently preparing their debut? They claim to have proof.
    The only natural response would be to have those skeptics try and disprove it, using their own methods of dating and compare the results.
    This being 2017, it seems only thing you need is a loud, shaming argument, no science required. Boom! Done.

  4. Ted Kowalski

    Dr. Jon Erlandson is an anthropologist at the University of Oregon says: “While I appreciate the discussion of taphonomy, potential stone tool use, and even some of the experimental butchery work, I am not convinced that this site and its contents are archaeological,” he told Western Digs.

    “From the photos of the tools, I am not convinced these are the real deal,” he added.”

    Typical comments often evoked by those jealous of the findings.

    Photographs? The famous expert can look at pictures of cobbles and decide authenticity? Without context of what cobbles are available to the mastodon butchering site?

    All of which amounts to a sour grapes award from the vaunted expert who wants inconvenient findings stifled.

    There is enough evidence for researchers to continue investigating the mastodon site; without listening to false criticism.

  5. Gerad Kipp

    Well every other ancient find that dates back 30 thousand to 3million in the north and south American Cotienent has been discredited with extreme Predijuce, the anthropologist leading the excavatiin is ruled a charlatan by his peers and blackballed for any further digs. The sites are destroyed, and the artifacts are lost forever. It’s an unwritten policy that the schools of grave robbers adhere too. I like the case of San Dia Points dating back 130 thousand years. In fact,other points were found fossilized in bat shit above the layers of San Dia Points. They were Clovis Points. “Forbidden Archology” recorded many ancient findings and the lead achiologist that was doomed from his finding. It’s worth the read, I like how he uses the technique to validate his findings.

  6. Kizh

    What happened to the. In the next 100,00p years. Just research the religion. A lot of the tribe in the surrounding area to as far as new mexico had a very similar religion. Also the area was full of life when the spanish came before massive amount of disease and the mission system eradicated the people. Then the gold rush happened and the population of indegenous people dropped to less than %1.