Is the fossil KNM-ER 1470 evidence that other dating methods other than the fossil record are inaccurate?

Question

The skull was originally dated to be almost 3 million years old. This led Richard Leakey, the son of famed archeologist Louis Leakey to comment, "Either We toss out this skull or we toss out our theories on early man. It simply fits no previous models of human beginnings." (National Geographic, June 1973

This 2.6 million year old date was verified by many different testing methods.

1. Based on other fossils that were very similar. Vertebrate faunas -- Elephant, Suid (pig), Australopithicus, and tools  (Maglio, 1972; Nature 239:379-85, Leakey, 1967-69, etc.)

2. On K-Ar and Ar40-Ar39 dating. Potassium-Argon dating -- selected crystals (K-Ar and Ar40-Ar39) (Fitch & Miller '70, Nature 226:226-8 and see 251:214)

3. Paleomagnetism. Paleomagnetism -- polarity data, based on 247 samples below KBS tuff (Brock & Isaac, 1974, Nature 247:344-48)

4. Fission Track Dating. Fission Track Dating -- involving uranium, noting possible reanealing (Hurford, 1974, Nature 249:236; '76, 263:738)

Eventually, these 2.6 million year date was revised to a more recent date (1.8 million years). Instead of tossing out the theory, they determined that the dating methods that all agreed on the 2.6 million timeframe must all be in error because the fossil record wasn't in agreement with the dates. This has led some credence to some creationists arguments that the dating methods aren't accurate.

Then in the late 1970's, a remarkable thing happened. One by one (with much heated controversy apparent in the papers) the other "independent methods" re-evaluated their work in light of the new radiometric date, and confirmed the new age:

I.E.: One by one all of those former "good" dates were scrapped in favor of a younger date which was more in agreement with the theory of evolution.

• Paleomagnetism -- pinpointing a different polarity reversal, in light of the change in the K-Ar date (Hillhouse et al, 1977,  Nature 265:411)

• Vertebrate Faunas -- three suid (pig) species (based on teeth) suggesting possible phylogenetic branching and its timing in relationship to the new radiometric date (Cooke, 1978; Science 201:460-63 (&198:13-21)

• Fission Track Dating -- (U-238 in zircon) emphasizing re-annealing, in light of the change in the accepted K-Ar date (Gleadow, 1980, Nature 284:229-230)

By 1980 there was a new "remarkably concordant" well-accepted radiometric date.

Do you see what happened? Many more dates than those mentioned here were obtained by radiometric methods, but the choice of which one to accept was made on the basis of the fossils (as you pointed out), because the acceptable range of dates for each fossil form was known (by evolutionary theory).

And this creationist page:

To make matters even more confusing, Garnis Curtis at Berkeley has recently used potassium argon dating on the KBS tuff and come up with younger dates yet. His first series of tests showed it to be 1.8 m.y.o. and his second series of tests showed it to be 1.6 m.y.o. To add chaos to confusion, recent fission track studies of zircons from the KBS tuff indicate an age of 3 m.y.o.! No wonder radiometric dating labs require that all samples to be "dated" be identified as to their source in the Geological column! Approximately 8 out of 10 specimens ("dates") are discarded by radiometric dating labs because they are well out of range of age they "ought to be" given there source in the geological column. In their book POTASSIUM ARGON DATNG, PRINCIPLES, TECHNIQUES AND APPLICATIONS TO GEOCHRONOLOGY, Dalrymple and Lanphere sum up the whole circular process of radiometric dating:

"If the potassium-argon ages of a group of rocks agree with the stratigraphic sequence determined on the basis of physical relationships of fossil evidence, then the probability is good that radiometric ages are reliable..." (page 197)

Was Richard Leakey correct, did they toss out the fossil, or the theories on early man? Were the first 4 (2.6 Million) dates thought to be accurate at the time of their original publication. Were they later revised to the more recent 1.8 million-years-ago timeframe? Is this evidence that the fossil record trumps all other dating methods (i.e. if there is disagreement, the fossil record is not revised, it is the other dating methods)?

Answer 1

First let me just give you a philosophical overview as to why the question is disingenuous and you are barking up the wrong tree. You ask:

Was Richard Leakey correct, did they toss out the fossil, or the theories on early man?

No, he was not. Of course, that is because he was taken out of context in that selective quote (a favorite creationist tactic). I'll lecture later on why he said it, but later in the same article, he also admits that he, or someone else could have made a mistake, and they needed to figure it out.

Were the first 4 (2.6. Million) dates thought to be accurate at the time of their original publication?

Not exactly, because again, this is creationist propaganda. If you actually read the cited papers, they aren't actually dating the skull, but other material found in the same strata as the skull, and in locations they thought were similar. Also, note the dates of all those publications. Methodologies have changed since the 1970s. Furthermore, we understand the geology of the area better, which has cleared up a lot of confusing results. Note that the skull was discovered in 1972, yet the creationist page uses papers from 1970.

Were they later "revised" to the more recent 1.8 million years ago timeframe?

Because that's what the evidence indicated they should do. Not because of the old and inaccurate radiometric results, but because they figured out their mistake... The ability for science to be a self correcting mechanism isn't a weakness or a fault, that is the strength. You seem to indicate that this is an unacceptable practice, yet I am sure the computer you are using isn't from the 1970s.

Is this evidence that the fossil record trumps all other dating methods (i.e. if there is disagreement, the fossil record is not revised, it is the other dating methods)?

No. The fossil record really isn't required to have evidence for evolution. However, what the fossil record does is give us a more detailed understanding of evolution. Of course, there aren't Post-It^(TM) notes attached to fossils describing all the circumstances of fossilization, what exact species it is, or exactly how it fits in to the evidence trail. That's what the scientists need to figure out.

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Okay, now to some more detailed rebuttals, and again, I am sorry if this seems like a lecture, but all to often, creationists will try to use one single misunderstanding to attempt to "prove" their point, while totally ignoring the mountain of evidence that makes their stance the height of ignorance and foolishness. They trot out the same lame arguments time and again, and never listen to the actual replies.

As to Leakey's quote, as a scientist, he understood that when you find an earth-shattering discovery that goes against or disagrees with what we know, there are several possibilities, two of the most commonly thought are:

• You have made an earth-shattering discovery that will totally rework everything we know about the field.

• You have made a mistake.

Scientists want and desire to make the first type of discovery. It's what puts them into the journals and history books. What usually happens is the second one. In the case of KNM-ER 1470, it was indeed the latter, but with a touch of the former. In this paper, Leakey admits to his mistake about the initial date and the KBS Tuff:

At present, analysis of samples collected for dating from the KBS Tuff in area 131 has proved inconclusive because of the apparent alteration of the sanidine felspars. This was not seen in the 105/108 samples from the same horizon which provided the date of 2.61 m.y. and there is no reason to suspect the validity of that date (personal communication from J. A. Miller).

However, as a result of all this investigation, he did figure out that he may be on to a new species in the genus Homo. Specifically Homo rudolfensis. Now that we have figured out that there is a new member of the genus Homo, the fact that creationists keep using this 40 year old argument, goes back to the fact that they don't listen... As the archeology info site states (emphasis mine):

The specimen was originally thought to be around 2.9 myr old, due to an inaccurate dating of 2.6 myr for the KBS volcanic tuff located above it. This inaccuracy was caused by contamination of older material, and the tuff is now know to be much younger. The specimen is now thought to date to approximately 1.8 myr (Leakey et al. may have been more willing to attribute the specimen to habilis had they known the real antiquity of the specimen from the beginning). Though this date is now generally accepted for the specimen, the geologists who orignally dated the KBS tuff continue to argue for a later date for the specimen. While they admit the dating of the volcanic tuff was inaccurate,

This page doesn't quote anything after 2000, and the 2001 paper with Leakey et al does figure out the problem with the Tuff.

One other problem that many people ignorant of human evolution fail to understand is that it's not a linear path. As a previous link mentions, several hominid species co-existed. Some became extinct, and some didn't. This is where Leakey actually made a great new discovery. Again, it's all part of the self correcting mechanism of science. Something was off, and at first they didn't know. Further investigation and scientific methodologies actually gave them clues, and then they had to revise what they thought they knew. This is the accepted scientific method, not blindly accepting the first thought that may come to one's mind. A paper that details a better understanding of the family tree was published by Bernard Wood (one of the men that help assemble the skull with Leakey:

Discussing the radiometric dating as it was understood in the 1970s compared to the 1990s and beyond, Dr Groves of Tufts university relays some information on KNM-ER 1470 that may be relevant:

White et al wrote of Aramis: "All hominid specimens were surface finds ..." This does not mean that they were rolled in from elsewhere; in fact, their condition indicates otherwise (there is a whole field called Taphonomy which is devoted to the study of how fossils got to be where they are). The date was also, at one point, queried by Kappelman and Fleagle (1995, Nature, 376:558-559), and satisfactorily answered by Wolde Gabriel et al. in the same edition of Nature.

This is an account of the history of the growth of understanding of the dating of the deposits; it is not some kind of admission of circular reasoning, of making the 40Ar/39Ar dates fit. They then go on to explain in some detail why Kappelman et al. misunderstood the argument about the dates.

[As an aside, there has been much speculation, informed and uninformed, about the reasons for the delay in publishing further information about Ardipithecus. White presented a paper at a congress in South Africa in late June/early July, 1998, attended by about 750 palaeoanthropologists and human biologists. The paper was illustrated by slides of the site and some of the fossil material. The site is flat, stony and arid; the fossils are scattered over the landscape, friable in the extreme, and difficult to collect, let alone to preserve. It is true that remains of at least 50 specimens ascribed to A.ramidus have been collected, but these will take years to preserve, fit together, study and describe.]

For Lubenow, this seems to be an attempt to make the radiometric dates fit the faunal analysis, which reminds him of the polemic over the date of the famous skull KNM-ER 1470, from Lake Turkana in Kenya. There was, he claims, such disagreement between radiometric and other dating techniques that it was finally dated by "biochronological comparisons", in this case the stages of evolution of pigs in East Africa.

Not true, actually. What is true is that the palaeontologists argued for some years for restudy of the K/Ar dating techniques, because their faunal analyses suggested that the date of the KBS Tuff, below which ER 1470 was found, was anomalous. Ian McDougall’s group finally managed to date material from which all contaminants had been eliminated, and showed that the palaeontologists were correct.

[Incidentally, the significance of these "stages of evolution of pigs" is passed over in silence by Lubenow. Surely he is not making a tacit admission that pigs did evolve! In creationism, neither humans nor pigs should evolve; and yet, there they are - several lineages of them, abundantly represented - in sites like Omo/Shungura, whose stratigraphy and dating are entirely uncontroversial, evolving away and eventually either becoming extinct or ending up as the modern Bushpig, Warthog and Giant Forest Hog. Elephants, incidentally, did the same thing, and their remains are likewise sufficiently numerous that their evolution can be tracked in great detail between about 4 and 1 million Ma.]

Again, this Taphonomy is a delicate science that may require decades to fully understand how something happened. And initial mistakes are remembered, while the correct answer seems to go ignored. Of course, this is nothing new from creationists.

If you need to get a Christian perspective, this individual takes a biblical approach, and still has to conclude that radiometric dating works and is accurate. A telling bit in that paper states:

Other creationists have focused on instances in which radiometric dating seems to yield incorrect results. In most instances, these efforts are flawed because the authors have misunderstood or misrepresented the data they attempt to analyze

Which seems to be the entire premise of the KNM-ER 1470 discussion. Nothing but misunderstanding and misrepresentation.

Answer 2

No, Leakey was not correct when he said, "Either we toss out this skull or we toss out our theories on early man." Instead, we tossed out the estimate for the age of KNM-ER 1470.

When he made this statement, Leakey had been placing higher confidence in the age of the large hominin skull he had found than his contemporaries did. This was not altogether unreasonable, since the various methods of paleomagnetism, fission track dating, and geochronology had already been used to check the 2.6 million-year-old K-Ar -and- Ar40/Ar39 estimate.

But after a "devastating" study about pig geochronology was published by Basil Cooke, scientists made several trips back to Africa to get additional data and came back with a younger estimate of this skull's age. This effort was still ongoing in 1985, when Ian McDougall published findings using the same nominal methods as was done in 1970 and gave the community a much more satisfying 1.8 million-year-old date for the KBS Tuff and Leakey's fossil skull.

Having thrown out the problematic (old) date, the community allowed homo habilis (later renamed Homo rudolfensis, after the body of alkaline water formerly known as Lake Rudolf) to keep its place after the australopithecines, such as "Lucy", whose remains were found just one year after Leakey's June 1973 proclamation in National Geographic Magazine.

Incidentally, this controversy immediately served as a "lesson learned" to other paleoanthropologists. After discovering "Lucy" in 1974, Donald Johanson went to the trouble of bringing a specialist to Africa before publishing so that the rocks that he would be using would be regarded as reliable the first time. Regarding Leakey's KBS Tuff dating, Johanson writes:

I was also acutely aware of a controversy that had been ballooning over the age of the KBS tuff at Koobi Fora. Although Richard Leakey still staunchly defended the date of 2.6 million that had been given it by two English scientists, Frank J. Fitch and Jack Miller, rumblings about it were growing louder and louder. A few months before, Basil Cooke had published a devastating paper on pig evolution. It showed that the Omo pigs from two million were identical with Koobi Fora pigs from the KBS tuff at 2.6 million. With a six-hundred-thousand-year discrepancy, there was something wrong, either with Cooke's pig analysis or with the Fitch-Miller potassium-argon date. Since Cooke knew how rigorous a collector Clark Howell was and how precise the dating at Omo was because of its many clear volcanic marker tuffs, he stood by his pigs. Leakey stood by Fitch and Miller.

I had begun to suspect that Leakey might be wrong, and was acutely aware of the enormously complex rearrangements that he would have to make in his thinking about hominid evolution if it turned out that he was indeed wrong. On the strength of the 2.6-million-year date for the KBS tuff, Leakey had asserted that his Homo habilis skull 1470 was 2.9 million years old, which made it difficult to accept any known australopithecine as an ancestor of Homo. Leakey therefore, and following his father's belief, had logically anchored himself in the view that australopithecines were collateral relatives, and that the Homo ancestor, when discovered, would turn out to be more Homo-like and less australopithecine-like than any fossil found so far. To rearrange all that in his mind on the basis of some pig fossils would be shockingly difficult. "Either we toss out this skull [1470]," he wrote in 1973, "or we toss out our theories of early man. It simply fits no previous model of human beginnings." He preferred to toss out the theory that australopithecenes were ancestors.

I was determined not to get into dating dilemmas; the Hadar figures would have to be rock-solid. I began to fret about the samples that had been sent to Aronson for potassium-argon dating; maybe they were bad samples. I realized that the only way I could reassure myself on that was to get Aronson to collect his own. I asked Taieb if he thought it would be a good idea to get Aronson to come to Hadar. [...] Aronson agreed to. He said he would arrive in December 1974, toward the end of the second field season.

Lucy: The Beginnings of Humankind By Donald Johanson and Maitland Edey, p. 170-171

Lexicon. Hadar: the region of Ethiopia where Lucy was discovered. Taieb, Maurice: together with Johanson and Yves Coppens, the team that discovered Lucy. Aronson, James: a contemporary potassium-argon expert from Case-Western University. Lucy: an australopithicene hominin. KBS tuff: the volcanic rocks found at Lake Turkana (formerly known as Lake Rudolf) at Koobi Fora, Kenya, that provide samples for the homo habilis radiometric date.

Another aspect of this controversy that is easy to overlook in textbooks and encyclopedia articles is the competitive nature of research in human evolution, and the superstar status that society places on researchers who make winning discoveries.

Here are a few excerpts from Johanson's book to demonstrate this.

My first public description of the knee joint was at a meeting of anthropologists held early in 1974 in New York by the Wenner-Gren Foundation, an organization founded by a Swedish industrialist to further anthropological research.

Everyone asked what on earth it was. I said I was not sure. All I could tell them was that it was bipedal and extremely small; if it was an australopithecine, it was smaller than any collected so far.

I thought I had been convincing; but when I was having lunch afterward with Mary Leakey, she said "I can't tell you who, but there are a couple of people at this conference who are saying those are monkey bones."

"But they're not," I said.

"Of course they're not. You know it; I know it. But it's always the way when you find something new. All those anatomists think they're so smart. They don't want to admit that somebody has found something different."

"They'll say that?"

"Of course they will. But you stick to your guns. You know what you've found. They're just jealous. Snickering away, saying, 'We'll wait until he publishes; then we'll carve him up.'"

Lucy: The Beginnings of Humankind By Donald Johanson and Maitland Edey, p. 164-165

Then later Johanson writes this:

On a stopover in Paris I had to go through Customs again. An official insisted on seeing what was wrapped up in all those funny little parcels in my suitcase. I explained that they were fossils from Ethiopa. "You mean Lucy?" said the Customs man. He was an anthropology buff and had read about her in the newspaper. A large crowd gathered and watched as Lucy's bones were displayed, one by one, on the Customs counter. I got my first inkling of the enormous pull that Lucy would generate from then on, everywhere she went. It also dawned on me that I was no longer an unknown anthropology graduate, but a promising young field worker with fossils dazzling enough to match those of paleoanthropology's certified supernova, Richard Leakey.

Lucy: The Beginnings of Humankind By Donald Johanson and Maitland Edey, p. 185

Answer 3

@Larian LeQuella 's answer above is not completely correct.

First of all, he completely ignores this fact from the linked website:

Early attempts to date the KBS tuff (1969) gave an age of 212-230 million years which was immediately rejected as an extraneous argon age discrepancy, because of the presence of Australopithicine and other mammalian fossils beneath the tuff (Fitch & Miller 1970, Nature 226:226-8).

In other words, scientists determine the validity/accuracy of a radiometric date depending on how the date fits in to how they think the fossil record should look like.

Meaning, if they find a human skull that is radiometrically dated to 500 million years ago, long before what they believe is the emergence of vertebrates, they automatically dismiss it as an error of the dating tool or that the sample was corrupted. This is a common practice in paleontology.

LeQuella also says,

If you actually read the cited papers, they aren't actually dating the skull, but other material found in the same strata as the skull

Little does he know that fossils, for the vast majority of the time, are dated by the geological strata in which they belong. In the case of this KNM-ER 1470 skull, the skull laid in a strata that was below the famous KBS Tuff. So, the date of the fossils was determined by the date of the KBS tuff.

LeQuella later says,

"No, [Leakey] was not. Of course, that is because he was taken out of context in that selective quote".

The quote is, "*Either We toss out this skull or we toss out our theories on early man. It simply fits no previous models of human beginnings.*"

Leakey was not taken out of context. He means what he says. Meaning, if you find evidence that refutes an accepted model, you have three options:

1) Discard the model

2) Dismiss the evidence as an anomaly

3) Or somehow show that the evidence is actually a mistake.

Now, scientists aren't so quick to dismiss their models, nor will they so easily dismiss potentially damaging evidence, so their only option is to somehow show that the dates arrived at were due to errors in the sample.

How do they do this? As LeQuella points out, scientists usually say the sample has been "contaminated" by material from older layers, giving the strata a much older date, but there is actually no way to know this. In fact, the sample could actually be contaminated by material from a newer strata giving a much more recent date!

In a potassium-argon study of formations in the western United States, geologist R.L. Mauger (1977, p. 37) stated: "In general, dates in the 'correct ball park' are assumed to be correct and are published, but those in disagreement with other data are seldom published nor are discrepancies fully explained".

And,

Geologist J.B. Waterhouse (1978 p. 316) noted: "It is, of course, all too facile to 'correct' various values by explanation of leakage, or initially high concentrates of strontium or argon. These explanations may be correct, but they must first be related to a time line or 'cline of values' itself subject to similar adjustments and corrections on a nonstatistical and nonexperimental basis".

It is entirely possible that geologists who are beholden to one or another set-of-assertions about biological cladistics make biased judgments about which rock samples are too weathered or otherwise compromised for accurate radiometric dating. It would go a long way toward eliminating this potential for biased results, and improving the next generation's chance at knowing the truth, if geologists and others would publish results from the rocks they don't accept---together with the data and reasoning they used in rejecting them.

Another important thing to note is that different samples in the tuff yield different dates. The samples from the KBS Tuff range from .52 to 221 million years ago.

Note, that one scientist involved in the KBS Tuff dating has said,

Radiometric dates, said E.T. Hall (1974, p. 15), "tend to acquire a spurious infallibility for the layman or for quasi-scientists like archaeologists. They believe because they want to believe".

This also applies to LeQuella's source where it says an "apparent alteration of Sanidine felspars" has caused the old date.

LeQuella then quotes Dr. Groves from the 1990's regarding the age of the KBS Tuff, who says, "

For Lubenow, this seems to be an attempt to make the radiometric dates fit the faunal analysis, which reminds him of the polemic over the date of the famous skull KNM-ER 1470, from Lake Turkana in Kenya. There was, he claims, such disagreement between radiometric and other dating techniques that it was finally dated by "biochronological comparisons", in this case the stages of evolution of pigs in East Africa.

In the next paragraph, Dr. Groves says that this isn't true.

Not true, actually. What is true is that the palaeontologists argued for some years for restudy of the K/Ar dating techniques, because their faunal analyses suggested that the date of the KBS Tuff, below which ER 1470 was found, was anomalous.

Despite what Dr. Groves says when he says, "not true", he is actually agreeing with Lubenow's analysis, that the radiometric dates are forced to fit into the faunal analysis, because Dr. Groves says the same thing. Dr. Groves says that the KBS Tuff was "anomalous" because of faunal analyses, which means they aren't satisfied with the radiometric dating, and so they want to re-date it based on the faunal finds, which is nothing other than picking a date that they think should belong in order to accommodate their preferred arrangement of the fossil record.