The Buenos Aires Skull

In 1896, workers were excavating the rudder pit of a dry dock in the port of Buenos Aires. They broke through a hard layer of limestone rock (called tosca). Beneath the tosca was a layer of quartz sand, and below that was a layer of gray clay, in which a human skull was found. This was about 11 meters (36 feet) below the bed of the river La Plata. The workmen gave the skull to their supervisor, Mr. Junor, who brought it to the attention of Edward Marsh Simpson, an engineer working for the English company that had the contract to excavate the dry dock. Simpson informed the Argentine archaeologist Florentino Ameghino about the discovery. The discovery (including the above-mentioned details) was announced to the scientific world in a lengthy report by Ameghino (1909). The details of the discovery can also be found in a report by the American anthropologist Aleš Hrdlička (1912, pp. 318-319), who came to Argentina to investigate the case.

Two aspects of the Buenos Aires skull were controversial: its species and its age. Ameghino was an evolutionist. He believed humans evolved first in South America and then spread to other parts of the world, whereas other evolutionary scientists of his time believed humans first appeared in Asia or Africa. Ameghino believed the Buenos Aires skull belonged to a South American precursor to the modern human species. He interpreted the skull as having a low forehead and low cranial capacity. Ameghino believed the skull was of Pliocene age. The Pliocene is a geological period extending from 2.58 million to 5.33 million years ago.

Hrdlička disagreed with Ameghino about both the species and age of the skull. When Hrdlička came to South America, Ameghino showed him the skull. Hrdlička (1912, p. 332) stated: “Every feature shows it to be a portion of the skull of man himself; it bears no evidence of having belonged to an early or physically primitive man, but to be a well-developed and physically modern-like human individual.”

Because the skull was of modern morphology, Hrdlička concluded it could not be as old as Ameghino thought. Hrdlička (1912, p. 2) stated: “On the basis of what is positively known today in regard to early man, and with the present scientific views regarding man’s evolution, the anthropologist has a right to expect that human bones, particularly crania, exceeding a few thousand years in age, and more especially those of geologic antiquity, shall present marked morphological differences, and that these differences shall point in the direction of more primitive forms.”

I agree with Hrdlička that the skull appears anatomically modern, but I disagree with him about its age. On this latter point, he was clearly influenced by his evolutionary prejudices.

As mentioned above, the skull was found in a layer of gray clay, below a hard layer of tosca, over 36 feet below the bottom of the La Plata. Regarding Ameghino’s judgment about the age of the gray clay, Hrdlička (1912, p. 321) said: “The gray clay he identifies as belonging to the upper-most portion of the Pre-Ensanadan formation.” Today some scientists call the Pre-Ensanadan (the formation below the Ensanadan) the Marplatan. The Marplatan goes from 2.15 million to 3.20 million years ago (Rabassa et al. 2005, p. 100), spanning the Early Pleistocene and the late Pliocene.  I therefore consider the Buenos Aires skull to be at least 2.15 million years old, from the Early Pleistocene period. Although more research on the geology of the site would be welcome, the original analysis by Ameghino conforms to recent descriptions of the stratigraphy of Buenos Aires. The presence of the tosca layer indicates that the sediments in which the skull was found were not disturbed, as had been suggested by American geologist Bailey Willis (Hrdlička 1912, p.345).

Some will ask if the skull has been dated by the radiocarbon method. Recently, in researching this case, I did come across a radiocarbon date for the Buenos Aires skull. In 1997, Jose Bonaparte, director of the department of vertebrate paleontology of the Bernardino Rivadavia Museum of Natural Sciences in Buenos Aires, where the skull is kept, sent a sample from the skull to the University of California at Riverside for accelerator mass spectrometry (AMS) radiocarbon dating. R. E. Taylor sent back a report, dated April 22, 1998, giving an age of 230 years for the sample (Politis and Bonomo 2011, p. 109). In the report, Taylor stated: “The analysis was taken on the total amino acid fraction by ion exchange chromatography after chemical and physical cleaning on the bone surface to remove any adhering contamination. The amino acid profile indicated that the bone still retained a considerable amount of collagen” (Politis and Bonomo 2011, p. 109).

At first glance, this radiocarbon date seems to cast strong doubt on an Early Pleistocene or late Pliocene age for the Buenos Aires skull. In radiocarbon dating, the preferred material for dating is collagen, bone protein. Proteins are made of amino acids. So in preparing a sample for dating, scientists use complex laboratory procedures to extract amino acids from bone samples. Taylor said that his analysis showed that the sample from the Buenos Aires skull contained amino acids typical of those normally found in collagen. But here is a problem: the bone may have been contaminated with recent collagen.

Researchers (Cook and Ward, 2008) restudied Neanderthal bones from the Krapina Cave in Croatia. The bones were excavated during the years 1899-1906. They are now kept in a museum in Croatia. The researchers found the bones had been treated with organic preservatives. They stated, “This was the usual practice at the turn of the twentieth century. In 1905 Rathgen recommended the application of natural resins such as dammar, shellac, isinglass and/or animal glues in appropriate solvents as a method of preservation for fossil bone” (Cook and Ward, 2008, p. 40). Friedrich Rathgen was a German expert on archaeological conservation, and he established standard techniques for preserving bone (and other archaeological materials) in museums (Rathgen, 1905). Significantly, he recommended that human fossil bones be preserved with animal glues, which are made from bone collagen (the word collagen comes from the Greek word kolla, which means “glue”). Rathgen (1905, pp. 151–152) recommended that fossil bones be completely permeated with glue by soaking them in a warm solution of glue and water. This procedure would completely impregnate the bone with recent collagen. Cook and Ward (2008, p. 41) said that tests on the Krapina bones “revealed the presence of bovine DNA, which could have resulted from the use of animal glue.” My point is that it is quite possible that the Buenos Aires skull was thoroughly permeated by animal glue (i.e. collagen) used as a preservative in a museum in Argentina early in the twentieth century.

If the formation in which the Buenos Aires skull was found really is the Pre-Ensanadan (Marplatan, according to current terminology), then the skull should be at least 2.15 million years old. An age like this would generally mean there should be no bone collagen left in the skull for radiocarbon dating. Even if there were some small amount of bone collagen left, it should not give any radiocarbon signal, because all the native carbon 14, which is radioactive, should have decayed into other elements within 100,000 years. If, as is likely, the skull were treated with animal glue as a preservative, this would have introduced recent collagen. The radiocarbon laboratory sample preparation procedures are meant to extract the amino acids that make up bone collagen. So in this case the amino acids that were extracted and radiocarbon dated were most probably from recent collagen (in animal glue) that gave an age of only 230 years. This age must be regarded with suspicion, because of the real possibility the skull could have been contaminated with recent collagen. On balance, the evidence suggests the Buenos Aires skull is anatomically modern and 2.15 million years old. Most scientists now believe that humans like us first appeared less than 200,000 years ago and entered the Americas about 20,000 years ago.


Michael A. Cremo is the author, with Richard Thompson, of the underground classic Forbidden Archeology: The Hidden History of Human Race. He has also written Human Devolution: A Vedic Alternative to Darwin’s Theory. (See

The Forbidden Archaeologist