In Part 3 of our exclusive series we looked at how the new science of paleoanthropology was being used in Europe while infighting paralyzed it in America when Aleš Hrdli?ka, stepped forward to end the disputations and promote professionalism and respectability.
By the 1920s, the Bering Strait Theory, and in particular the idea that American Indians had settled in the New World less than 5,000 years ago, had become a rigid dogma that no scientist who valued their career would dare to challenge.
In the end, it was a group of amateurs who exposed the charade. In 1908 George McJunkin, an African-American cowboy born the son of former slaves, was tending cattle at the Crowfoot Ranch near Folsom, New Mexico, when he discovered the remains of an animal that had been uncovered after a recent flood. He recognized the bones as a bison, and surmised that it was of some ancient type.
McJunkin informed a local blacksmith and amateur naturalist, Carl Schachheim, who then informed his friend and fossil hunting companion, Fred Howarth, a banker. After visiting the site, they tried repeatedly to interest paleontologists into excavating it without success. Finally, their persistence paid off in 1926, when Harold J. Cook and Jesse Dade Figgins of the Denver Museum of Natural History agreed to take a look. They quickly found, not only extinct bison, but spear points. This was a “kill site,” the results of a hunt. Since the established dogma insisted that kill sites of extinct animals did not exist, they worked very, very carefully, hoping to find something–anything–that might be conclusive.
On August 29, 1927, an ancient stone spear point was found embedded between the ribs of an extinct bison. This was clearly no accident. Recognizing the importance of the discovery, the find was left intact in the ground to be witnessed by as many eminent archaeologists as they could muster. Although he tried, Hrdli?ka could not reject this. The indisputable evidence had surfaced, and one glass floor had been shattered.
With the acceptance of the Folsom point, it became clear that humans were in the Americas more than 5,000 years ago. No longer hamstrung by the need to overturn dogma, a flurry of sites were discovered in the next few years which began to change the picture of ancient America. In 1932, near Clovis, New Mexico, a site was uncovered that featured the same type of spear point found at Folsom, and then digging deeper, a different and older set of spear points were found. Humans had been in America at least 10,000 years or more. It had been 68 years since the Europeans accepted the antiquity of humans, but finally, the American paleoanthropologists had joined the club.
It is important to note that it was not the discovery of human remains, so emphasized by Hrdli?ka, but of human tools in the right context, that changed the perceptions of the past. This was also the case in 1859 in Europe, when the stone tools of Brixham and the Somme led to the acceptance of human antiquity. The value to science of human remains in certain cases may be important, but it has not been decisive.
But if the time frame for human antiquity in the Americas had changed, the story had not. The Bering Strait Theory remained the unchallenged assumption. The line was drawn hard and fast once again, this time at 10,000 BC.
“Clovis First,” the new version of the Bering Strait Theory, was based on the presumption that the Paleoindian culture that had produced the spear points found at the Clovis site were the first settlers. In part, this was because of the Clovis site itself, which had in layer after layer revealed thousands of years of settlement history, but nothing was found in the layer beneath the Clovis culture. The other factor was the growing awareness among paleoanthropologists that the presumed pathway between Asia and the Americas, the Bering Strait, may not have always been open, but may at times have been impassable.
By 1932, geology had progressed to the point that an accurate map of the giant ice sheet could be drawn with reasonable certainty. A general consensus had developed among geologists that the glaciers were impassible approximately 30,000 years ago and very likely through to 10,000 years ago, about the time when the Clovis culture was beginning. The Clovis First Theory naturally dismissed the idea that Paleoindians might have arrived before 30,000 years ago (before the Last Glacial Maximum or LGM).
In 1933, the Canadian geologist William Alfred Johnston proposed that when the glaciers began melting, they broke into two massive sheets, one centered on the Pacific Coast and Rocky Mountains (later named the Cordilleran ice sheet), and the other, now known as the Laurentide ice sheet, covering the rest of Canada all the way to the Atlantic Ocean. In between these two massive ice caps, people might have been able to walk from Alaska down into the United States. Two years later, the Swedish-American geologist Ernst Antevs dubbed this route, the “ice-free corridor.”
The date when the melting of the ice sheets opened the ice-free corridor, believed to be around 13,000 BC, seemed to give just enough time for the Clovis culture to walk from Alaska and spread all across the Americas.
Retiring in 1942 as head of the anthropology department of the National Museum, a position he had held for almost 33 years since replacing William Henry Holmes in 1909, Hrdli?ka died the following year. His legacy, however, continued. The Bering Strait Theory, now in its new incarnation, Clovis First, was upheld with equal dogmatism by a new generation of paleoanthropologists who had grown up with no other perspective.
Bend it like Beckham
As new scientific methods began to play an important role in the examination of artifacts, new battles began almost immediately. Radiocarbon dating, developed in 1949 by Nobel Prize-winning chemist Willard Libby, revolutionized archaeology. By measuring the decay of a radioactive isotope of carbon, carbon 14, in any dead organic matter such as bones, wood, or plants, Libby found an approximate way to date when it had died.
During the construction of a dam in Lewisville, Texas the remains of a bison were uncovered in 1949, leading to a series of excavations that continued until the dam was finished and the site inundated in 1957. The excavations, as archaeologists Wilson W. Crook, Jr., and R.K. Harris wrote in the journal American Antiquity, “yielded remains of more than 21 hearths of an ancient campsite of early man. An extensive Upper Pleistocene fauna has been recovered, much of it actually burned within the hearths themselves, and the remainder closely associated with camp refuse, along with certain distinctive artifacts.” What created a stir was that two of the hearths were radiocarbon dated at more than 37,000 years old.
Since this flew in the face of the Clovis First Theory, the findings were instantly attacked. But given the indisputable (at that time) radiocarbon dating, that was not going to be easy to do. The archaeologists Robert F. Heizer and Richard A. Brooks (both of whom did not visit the site) responded in the Southwestern Journal of Anthropology in a manner that would have made Aleš Hrdli?ka proud.
The evidence for association of stone tools with the hearths is insufficient to provide a valid case for arguing that the hearths are the result of human agency. If we are to accept the proposition that man has been in the New World for more than 37,000 years, the least we can demand is that the evidence for the belief be unambiguous.
They then proposed that the hearths were actually ancient nests of wood rats, an idea so absurd on its face (presumably the wood rats also cooked the extinct animals found burned in the hearths), that the whole matter was dropped and ignored. Since it could not be disputed, the Lewisville site was consigned to the academic dustbin.
Twenty-five years later, as archaeologists gained experience with radiocarbon dating and learned that a contamination of samples or other factors could influence the dates given, the geologist D. L. Johnson proposed that maybe the Lewisville site had been contaminated by lignite (brown coal) from nearby outcroppings of the Woodbine Formation, which was around 70 million years old. A dry spell in 1979 had allowed for a new excavation and so material from the Lewisville site was sent for reanalysis.
Unfortunately for the Clovis First Theory, a report produced in 1985 by a team from the Illinois State Geological Survey headed by Richard H. Shiley, entitled “Moessbauer Analysis of Lewisville, Texas, Archaeological Site Lignite and Hearth Samples” found that whatever was burned in the hearths, it was not Woodbine lignite.
The rare earth composition of Woodbine Formation lignite and its corresponding ash are very similar to one another, but are not similar to the soil or hearth samples. The rare earth composition of the surrounding soil follows the same pattern as that of the hearth. From this data, it is reasonable to provisionally conclude that the Woodbine Formation lignite was not burned in the hearths.
A second test then found that, “pyrite combustion products were not detected using X-ray diffraction.” Pyrite, found in lignite, when burned should generate a byproduct, but none were found. Whatever was burned in the hearths was not lignite.
A third test, now using Moessbauer spectroscopy, also did not find pyrite byproducts in the charcoal of the hearths tested, but did find trace amounts of hematite, a pyrite byproduct, in the sediment lining of one of the hearths, hearth 22, a hearth that had been excavated in 1979, after the site had been submerged by the reservoir. The Moessbauer test did not find traces of lignite in the hearths excavated in the 1950s by Crook and Harris. By all rights, the radiocarbon dates of more than 37,000 years still stood.
The team, clearly disappointed it had not come up with the expected result, put the best face it could on its findings.
The use of the Moessbauer spectroscopy, on the other hand, produced positive results. Hematite, a pyrite combustion product, was found in hearth 22. We concluded that there is some support for the hypothesis that Woodbine Formation lignite was burned in this hearth, thus increasing the apparent age (radiocarbon date) of the hearth material.
Thankfully the tepid “some support for the hypothesis” was all that was needed. Few were going to bother to read the actual report and nobody wanted to dispute its conclusions. Lewisville was pronounced as having been contaminated by lignite and was no longer a problem for the Clovis First Theory.
The orthodoxy was stronger than ever. No longer under Hrdli?ka’s iron grip, it was now self-policing. Whatever the scientific data might say, the conclusions would somehow support the theory. Any site that promised to be earlier than Clovis was going to be subject to unrelenting scrutiny until something was found wrong with it. New evidence would be “bent” towards upholding the Bering Strait Theory.
The established dogma could still only be overturned by “indisputable proof,” the nature of this proof being defined by the dogmatists themselves. Despite the discovery of the Folsom point in 1929, the same intellectual stubbornness that Hrdli?ka had fostered continued to stunt paleoanthropology.