Originally published in Creation 17, no 3 (June 1995): 36-38.
A popular myth is that radioactive dating methods confirm the geologic time-scale and the concept of human evolution.
The methods appear so impressive that many Christians accept them as evidence that the earth is very old. The best way to expose this myth is to study the dating of the East African KBS Tuff strata and the famous fossil KNM-ER 1470.1
Richard Leakey, son of famed palaeoanthropologists Louis and Mary Leakey, visited the fossil deposits east of Lake Rudolf (now Lake Turkana) in northern Kenya in 1967. He immediately organized an expedition to search for hominid fossils.
The most important fossil discovered there is KNM-ER 1470. Skull 1470 is modern in appearance, but was originally estimated by Richard Leakey to be about 2.9 million years old.
One early geologist with Richard Leakey at East Rudolf was Kay Behrensmeyer. Seeking to unravel the geology of the area, she discovered a layer of volcanic ash or tuff that became known as the Kay Behrensmeyer Site (the KBS Tuff).
If the KBS Tuff were anywhere else, no one would give it a second thought. At East Rudolf it is of utmost importance. First, although human fossils and artefacts (tools) cannot usually be dated radiometrically, the KBS Tuff can. It contains radioactive potassium 40, which decays to argon 40. Second, artefacts have been found in association with the KBS Tuff. The assumption is that the tuff gives an estimate of the age of the stone tools. Third, hundreds of Homo and australopithecine fossils have been found above and below the KBS Tuff. The date of the tuff thus becomes a maximum age for fossils found above it and a minimum for fossils below it.
The first attempt to date the KBS Tuff was in 1969, well before the discovery of skull 1470. Richard Leakey supplied rock samples to F.J. Fitch (Birkbeck College, University of London) and J.A. Miller (Cambridge University) — recognized authorities in potassium-argon (K-Ar) dating.
Fitch and Miller's first analysis gave evolutionary dates from 212 million to 230 million years of age. Concerning this they said, 'From these results it was clear that an extraneous argon age discrepancy was present ...'.2 How did they know? The associated fossils told them. In spite of our being assured that dating methods constitute independent confirmation of evolutionary dates, associated fossils had already determined the 'acceptable' dates. Based on their alleged evolution, the australopithecine and other mammalian fossils found beneath the KBS Tuff had determined that the rocks should be between 2 and 5 million years old.
Dates of 212 to 230 million years old were far off. Without the associated fossils, however, there would be no way for an evolutionary geologist to know if these were 'good' or 'bad' dates. Under other circumstances, and without fossils to guide them, evolutionary geologists could have accepted these dates as 'good'.
Fitch and Miller requested new samples. From these they concluded from pumice lumps and feldspar crystals that the age of the KBS Tuff was 2.61 million years.3 It was because Leakey found skull 1470 below this tuff after it had been dated at 2.61 million years and above rock dated at 3.18 million years that he estimated the skull to be 2.9 million years old.
In 1972, before skull 1470 was announced, Vincent Maglio (Princeton University) published in Nature a chronology of the hominid-bearing sediments east of Lake Rudolf, which included the KBS Tuff.4 His work was based on lineages of two species of pig and one of elephant. Maglio's dates were compatible with the radiometric date arrived at by Fitch and Miller, and were considered to confirm their date.
In 1974, a third chronology of the area was published in Nature, based on palaeomagnetism.5 The conclusion of 2.7 to 3.0 million years seemed to represent a 'bulls-eye' for the correlation of the various dating methods.6
By late 1974, the KBS Tuff had been dated five different times by four different dating methods. The alleged compatibility of the different methods would seem to be a geologist's dream.
However, under the surface, skull 1470 with its estimated date of 2.9 million years presented the evolutionary world with an intolerable situation. The theory of human evolution did not allow a skull so modern to be that old. Nevertheless Richard Leakey continued to fight for this original date. If skull 1470 was 2.9 million years old, he had discovered the oldest member of the genus Homo; if it wasn't, he hadn't! Hence, he resisted lowering the age of the skull.
Meanwhile, another study by G.H. Curtis and his associates (University of California, Berkeley) claimed to distinguish two tuff units. One gave an age of 1.6 million years and the other, where skull 1470 was found, gave 1.82 million years — both considerably younger than the five previous studies had reported.
All of the above-cited articles spoke of the great difficulty in getting rock or crystal samples that were not altered, weathered, or derived from older rock. The question arises, How does one know when one has good samples for dating? The answer is that 'good' samples give dates in accord with evolutionary presuppositions. 'Bad' samples give dates not in conformity with evolution — a classic illustration of circular reasoning.
On March 20, 1980, two more dating studies in Nature criticized the earlier work and claimed that the age of the KBS Tuff was 1.87 or 1.89 million years. Then in late 1981, Ian McDougall published his study of the KBS Tuff, giving a date of 1.88 million years. At that point, the 10-year controversy over the date of the KBS Tuff came to a close with agreement on the more recent date.
Although the dating of the KBS Tuff appeared to be settled in 1980 and 1981 by the conformity of different dating methods, the controversy was actually settled in 1975 by the pigs.
Donald Johanson tells of attending the 1975 Bishop Conference on anthropology and geology in London. A major paper was presented by Basil Cooke (Dalhousie University, Halifax), who had studied the pig sequences in southern Ethiopia, at Hadar (Ethiopia), and at Olduvai Gorge (Tanzania). According to Cooke, the dating at Lake Turkana (formerly Lake Rudolf) was too high by about 800,000 years. The pigs at Turkana told him so.
Johanson wrote of this conference: 'Nearly everyone but the Lake Turkana team [Richard Leakey and his associates] went away convinced that the KBS tuff and the skull-1470 dates would have to be corrected.'7
Astounding about the whole affair was that the anthropologists were rejecting the same objective, scientific data they universally appeal to. There was internal consistency within the studies, and high conformity by five different dating techniques. The main thing the dates did not conform to was the concept of the evolution of pigs and humans.
The evolution of the pigs is said to be the clear-cut answer to the dating problems in east Africa, but the evidence is less than impressive. In his phylogeny of the pigs (bush-pig, forest hog, warthog, etc.), Basil Cooke presented family trees for three taxonomic groups. Two of the groups have at their bases the phrase hypothetical Sus-like ancestor. The 20 species that make up these three groups are shown in parallel lines connected only by dotted lines, indicating that there is no known relationship between any of the species. The chart could just as well have been drawn by a creationist.
Most of the fossil-pig evidence consists of teeth. Several species are based on the skimpiest evidence ('imperfectly known', 'rare', 'scarce') and the various relationships are largely guesses.
The 1980 and 1981 studies on the date of the KBS Tuff contained so many criticisms of all of the earlier studies that they called into question the objectivity and validity of the dating methods themselves.
The above account highlights two major fallacies of radioactive dating. First, the history of the dating of the KBS Tuff reveals that no matter how careful a scientist is in selecting his rock samples and in performing his laboratory work, if he gets the wrong date for his rocks he is open to the charge of using contaminated material and defective methodology. The charges need not be proved. The literature suggests that even if radiometric dating were valid in concept (which it is not), the practical matter of selecting rock samples that can be proved pure and uncontaminated requires an omniscience beyond humans. The radioactive dating methods are a classic example of self-deception and circular reasoning. It is another of the myths of evolution.
Second, what normally happens in a fossil discovery is that the fossils are discovered first. Then attempts are made to date the rock strata in which they are found. Under these conditions, a palaeoanthropologist has a degree of control over the results. He is free to reject dates that do not fit the evolution scenario of the fossils. He is not even required to publish those 'obviously anomalous' dates. The result is a very sanguine and misleading picture of the conformity of the human fossil record with the concept of human evolution.
It is entirely possible that if skull 1470 had never been found, the KBS Tuff would still be dated at 2.61 million years. We would continue to be told that it was a 'secure date' based on the precision of radiometric dating and the 'independent' confirmation of other dating techniques that acted as controls. It was the shocking discovery of the morphologically modern skull 1470, located well below the KBS Tuff, that precipitated the 10-year controversy.
In the 10-year controversy over the dating of one of the most important human fossils ever discovered, the pigs won. The pigs won over the elephants. The pigs won over potassium-argon dating. The pigs won over argon40/argon39 dating. The pigs won over fission-track dating. They won over palaeomagnetism. The pigs took it all. But in reality, it wasn't the pigs that won. It was evolution that won. In the dating game, evolution always wins.
KNM-ER 1470 (Kenya National Museums — where it is housed; East Rudolf — where it was found; and 1470 — the museum acquisition number).
F.J. Fitch and J.A. Miller, 'Radioisotopic Age Determinations of Lake Rudolf Artifact Site', Nature 226, April 18, 1970, p. 226.
ibid, p. 228.
Vincent J. Maglio, 'Vertebrate Faunas and Chronology of Hominid-bearing Sediments East of Lake Rudolf, Kenya', Nature 239, October 13, 1972, pp. 379-85.
A. Brock and G. Isaac, 'Paleomagnetic stratigraphy and chronology of hominid-bearing sediments east of Lake Rudolf, Kenya', Nature 247, February 8, 1974, pp. 344-8.
ibid, p. 347.
Donald C. Johanson and Maitland A. Edey, Lucy: The Beginnings of Humankind, Simon & Schuster, New York, 1981, p. 240. Bracketed material added for clarity.