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In paleoanthropology, we sometimes encounter the definitive debunking report-one that is used again and again to invalidate certain evidence. In the case of European eoliths, there are two good examples of definitive debunking reports. These are H. Breuil' s paper claiming that pseudoeoliths were formed by geologi­cal pressure in the French Eocene formations at Clermont (Oise), and A. S. Barnes's paper claiming to demonstrate, by statistical analysis of platform striking angles, the natural origin of Eolithic industries.

In 1910, Henri Breuil conducted investigations he thought would put an end to the eolith controversy. In his often cited report, he said he found flints resembling stone tools in the Thanetian formation at Belle-Assise, near Clermont, France. This formation is Early Eocene, making the flints about 50-55 million years old. But Breuil could not imagine human beings-existed in the Eocene. How, then, had the flint objects been produced? During his excavations, Breuil found a few pieces of flint with detached flakes lying nearby. Some of these detached flakes had bulbs of percussion. Others had some flaking on them that resembled retouching. The cause of these effects, according to Breuil, was sim­ply geological pressure.

Can geological pressure really cre­ate the effects observed by Breuil? Leland W. Patterson, a modern au­thority on stone tools, says that pres­sure flaking very rarely produces clearly marked bulbs of percussion. It usually takes an intentionally directed blow.

Breuil probably selected for illus­tration his best examples of flakes found in contact with the parent block of flint. But the flaking and retouching on them is far cruder than on the cores and flakes selected by Breuil as examples of pseudoeoliths. Breuil said all the effects resulted from natural geological pressure flaking. But he would have been justified in making such a statement only if he had found the flakes from better looking eoliths in contact with their parent blocks of flint. And this he did not do.

The unsatisfactory nature of Breuil's geological pressure hypothesis becomes even clearer when we consider what Breuil called "two truly exceptional objects, of which the site of discovery, in the interior of the beds, is absolutely certain."

Breuil said the first object was virtually indistinguishable from an Azilio-Tardenoisian grattoir, or end scraper. Scientists generally attribute Azilio-Tardenoisian stone implements to Homo sapiens sapiens in the Late Pleistocene of Europe. In describing the second exceptional object, Breuil compared it to tools found at Les Eyzies, a Late Pleistocene site in France. Geological pressure flaking does not seem adequate to explain these two tools, which are over 50 million years old.

Breuil's paper is still cited as proof that eoliths are natural rather than artificial productions. This kind of citing is a very effective propaganda technique. After all, how many people will bother to dig up Breuil's original article and see for themselves if what he had to say really made sense?

Breuil's definitive 1910 report came before most of J. Reid Moir's discoveries in East Anglia. Eventually, when Moir's finds began to attract attention, Breuil went to England to conduct firsthand evaluations. Surprisingly, Breuil backed Moir. He accepted the implements from the Pliocene Red Crag at Foxhall as genuine and also said that some of the implements from the beds below the Red Crag were "absolutely indistinguishable from classic flint implements." The sub-Crag formations could be anywhere from 2 to 55 million years old. Breuil apparently became noncommittal later on. The 1965 edition of his book Men of the Old Stone Age, published after his death, stated only that "a certain number of flakes might be accepted, though their angle of cut is generally against it." One wonders why there is no mention of the objects Breuil previously said were "not simply eoliths but are absolutely indistinguishable from classic flint implements."

Another important element in the eolith controversy was the platform angle test, promoted by Alfred S. Barnes. Barnes, who defended Moir in the 1920s, later became opposed. In 1939, he delivered what many authorities still regard as the death blow to Moir's English eoliths. But Barnes did not limit his attention to Moir. In his study, titled "The Differences Between Natural and Human Flaking on Prehistoric Flint Implements," Barnes also considered stone tool industries from France, Portugal, Belgium, and Argentina.

Supporters of eoliths generally argued that natural forces could not produce the kinds of chipping observed on the objects in question. Barnes looked for some measurable way to demonstrate whether or not this was so. For this purpose, Barnes chose what he called the angle platform-scar. "The angle platform-scar " he said, "is the angle between the platform or surface on which the blow was struck or the pressure was applied which detached the flake, and the scar left on the tool where the flake has been detached." In genuine human work, the angle would be acute. Natural fractures would, he said, yield obtuse angles.

We find Barnes's description of the angle to be measured somewhat ambigu­ous. We have spoken with experts on stone tools at California's San Bernardino County Museum, in­cluding Ruth D. Simp­son, and they have also been unable to specify exactly what angle Barnes was measuring. In any case, in the angle platform-scar, Barnes believed he had found the objectively measur­able feature by which one could distinguish natural chipping from human work.

To be effective, the measurement had to be applied not to a single specimen, but to a large sample of specimens from the industry in question. Barnes stated that a sample "may be considered of human origin if less than 25% of the angles platform-scar are obtuse (90 degrees and over)." Having established this, Barnes delivered a devastating conclusion: none of the eoliths he examined, including those of Moir, were of human origin. Interestingly enough, it appears that Moir himself was aware of the Barnes criterion and believed his specimens were within the required range. But for Barnes, and almost everyone else in the scientific community, the controversy was over.

In fact, in mainstream circles the controversy about the eoliths and other Tertiary stone tool industries had long since ceased to be a burning issue. With the discoveries of Java man and Beijing man, the scientific community had become increasingly convinced that the key transition from apelike precursors to toolmaking humans (or protohumans) had taken place in the Early to Middle Pleistocene. This made the presumed stone tools of humans in the Pliocene and earlier a sideshow topic of little concern. Barnes, however, performed the valuable, if menial task, of sweeping away some useless remnants of irrelevant evidence. Thereafter, whenever the topic of very old stone tool industries happened to come up, as it still does from time to time, scientists could conveniently cite Barnes's report. Even today scientists studying stone tools apply the Barnes method.

But on close examination, it appears that Barnes's definitive debunking report may be in need of some debunking itself. Alan Lyle Bryan, a Canadian anthropolo­gist, wrote in 1986: "The question of how to distinguish nature facts from artifacts is far from being resolved and demands more research. The way the problem was resolved in England, by application of the Barnes' statistical method of measuring the angles of platform scar, is not generally applicable to all problems of differentiating nature facts from artifacts." During a phone conversation with one of us on May 28, 1987, Bryan also expressed a cautious belief that Barnes may have gone too far in trying to eliminate all of the anomalous European stone tool industries. Giving attention to more recent discoveries, Bryan said that there are Late Pleistocene Australian tools that do not conform to Barnes's specifications.

Another example of an industry that apparently does not conform to the Barnes criterion is the Oldowan, from the lower levels of the Olduvai Gorge. Considering the extremely crude nature of the objects, which Louis Leakey said were compa­rable to Moir's implements, it is remarkable that they have never been challenged by the scientific community. This is probably because the Oldowan industry offers support to the African evolution hypothesis of human origins, which is accepted as dogma.

In light of the views presented by Bryan and others, it is clear that wholesale rejection of the Eolithic and other early stone tool industries by application of the Barnes criterion is unwarranted.

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