From the 1929 collection on the Del Mar bluffs to the 1974 claim of 48,000 years, the 1984 retraction and the 1989 date. All records sourced and cited.
In 1974 a team at Scripps Institution of Oceanography published an age for a skeleton that had been sitting in a San Diego museum for forty five years. The bones had come off a bluff at Del Mar. The number they published was 48,000 years, which would have made this person the oldest human being ever found in North America by a wide margin.
The number was wrong by roughly a factor of ten. The correct figure, settled in 1989, is 4,900 years. What makes it worth writing down is who dismantled it: Jeffrey Bada, the lead author of the 1974 paper, published the retraction himself ten years later in Nature.
An objection to the method had appeared in print the same year the claim did. It took fifteen years to finish the argument.
Malcolm J. Rogers recorded the site in 1929, splitting it into a lower terrace near water level and an upper cliff terrace. The county record still carries it as the Del Mar Man Site. Rogers collected human remains from at least two features that year, and became full time curator at the San Diego Museum of Man in 1930.
Two bones from that collection later went through the dating labs: a sphenoid, which is a bone at the base of the skull, and a tibia. The full skeletal description was not published until 1974.
There is no contemporaneous account of the discovery. No newspaper report, no field note, nothing. For forty five years these were bones in a drawer.
The paper is Bada, Schroeder and Carter in Science, volume 184. The third author, George F. Carter, was a Johns Hopkins geographer who had spent decades arguing that humans reached San Diego far earlier than anyone accepted.
Amino acid racemization measures how far the amino acids in a protein have drifted from one mirror image form to the other. The drift is steady, so in principle it is a clock. It needs a calibration sample, and Bada's team used a Laguna Beach skeleton radiocarbon dated to 17,150 years.
Del Mar came out at 48,000 years and a companion skeleton from Sunnyvale at 70,000. Neither number was published with error bars.
The objection arrived in the same journal year. Michael Bender published in Nature in 1974 that the racemization rate is roughly twenty percent sensitive per degree Celsius, so calculating an age demands that you already know the sample's temperature history. Bender did not mention Del Mar by name. He did not need to.
The United States Geological Survey went at it with a different method. Bischoff and Rosenbauer published uranium series dates in Science in 1981: Del Mar at 11,000 years, Sunnyvale at 8,300. Their abstract says these ages are significantly younger than the racemization estimates and indicate the individuals could derive from the population waves that crossed the Bering Strait during the last sea level low.
Science ran a technical comment attacking the uranium dates in 1982, with their reply printed alongside it. The fight was in the open.
Bada took the original amino acid extracts, the exact material from the 1974 study, and ran them through accelerator mass spectrometry radiocarbon dating with three colleagues at Oxford. The paper ran in Nature in 1984.
His own abstract acknowledges the intense controversy the 1974 dates had set off. It then says the new work shows that some of the controversial California skeletons assigned to the Pleistocene are in fact Holocene, meaning younger than about 11,700 years.
The following year eleven authors published the broad version in American Antiquity under a title that left nothing to interpret: "Major Revisions in the Pleistocene Age Assignments for North American Human Skeletons by C-14 Accelerator Mass Spectrometry: None Older Than 11,000 C-14 Years B.P."
A 1986 paper in Radiocarbon laid out three separate reasons the method had gone wrong on these bones.
The first is the one Bender had named in 1974. The calibration required that the reference sample and the sample being dated had experienced essentially identical temperature histories, which the authors call an unrealistic assumption.
The second is worse. The clock was set against that Laguna Beach skeleton, and the anchor itself was bad. A clock calibrated against a wrong reference reads wrong everywhere.
The third is chemical. Groundwater leaching left the collagen unevenly preserved, and poorly preserved bone showed inflated ratios. Chemically degraded bone looks old to this method no matter how old it actually is.
The definitive number came in 1989, from Thomas Stafford and Rose Tyson, the Museum of Man's own curator of physical anthropology. They dated individual amino acids from the Del Mar sphenoid and got an average of 4,900 years, plus or minus 40, which their abstract says conclusively establishes the age for the Del Mar skull.
They also found that the tibia, the other bone from the original study, was contaminated with amino acids from outside the bone. Its age is still uncertain.
It means this person was not a Pleistocene pioneer. At roughly 4,900 years before present they fall inside the La Jolla complex, the middle Holocene pattern of coastal southern California: manos and metates, flexed burials, heavy reliance on shellfish. That way of life was already thousands of years old on this coast by the time this person lived.
San Diego County does hold genuinely ancient human remains. A burial from a La Jolla site has been radiocarbon dated to between 9,590 and 9,920 years before present. Del Mar Man is not one of them.
In 1992, during freeway work in National City, Richard Cerutti of the San Diego Natural History Museum found broken mastodon bones. In April 2017 a team published in Nature that the bones were about 130,700 years old and had been broken deliberately by humans using cobbles as hammers and anvils. If true it would move the human arrival in the Americas back by more than a hundred thousand years. The critics point out that there are no modified stone tools, no stone debris and no human remains at the site.
These two stories get run together and they should not be. What they share is real: both are San Diego County claims to extraordinary human antiquity, both rested on one uncommon dating technique rather than converging lines of evidence, and both drew immediate sustained professional rejection. There is even a direct thread, because George Carter, co-author of the 1974 Del Mar paper, spent his career making this argument.
What they do not share matters more. Del Mar is human bone. Cerutti is mastodon bone and rocks, with no human remains at all. They are about twenty five miles apart, dated by different methods, in different decades. And Del Mar is closed, retracted by its own author, while Cerutti is still open and its authors are still defending it in print.
The sentence to avoid is that San Diego produced two claims of extremely ancient humans and both were debunked. One was withdrawn by the man who made it. The other is an argument still underway. That argument is its own story: the Cerutti mastodon.
As of the 1989 paper the remains were at the San Diego Museum of Man, now the Museum of Us. In early 2016 that museum returned 66 individuals from five La Jolla area sites for reburial, under a Federal Register notice finding a relationship of shared group identity that can be reasonably traced to the Kumeyaay Nation, with eleven bands named as claimants.
The Del Mar remains are not in that notice, and not in any of the other repatriation notices that museum has filed. Public records do not establish that these remains have been repatriated and do not establish that they have not.
A different case nearby shows how hard that ground is. Two skeletons found in 1976 during construction at the UCSD chancellor's residence in La Jolla, dated to roughly 9,000 to 9,600 years, became a federal lawsuit when three UC professors sued in 2012 to block their transfer so DNA work could go ahead. The Ninth Circuit affirmed dismissal in August 2014, the Supreme Court declined to hear it in January 2016, and the remains went to the La Posta band.
The bluffs that produced the skull are the same bluffs that set the price of everything west of the railroad in Del Mar. See the current numbers on the Del Mar market report, updated monthly from closed MLS sales.
More San Diego history: every story, oldest history first.