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KNM-ER 1470

The skull was originally dated to be almost 3 million years old. This led Richard Leaky, the son of famed archeologist Louis Leaky 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, Leaky, 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-anealing, 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 Leaky 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 triumphs all other dating methods (I.E. if there is disagreement, the fossil record is not revised, it is the other dating methods)?

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That earthage website is ALSO a creationist website. I would also like to know which NatGeo that first quote is from so I can get the entire context of the quote. This questions seems disingenuous at best. –  Larian LeQuella Jun 5 '12 at 10:48
Man, talk about "liars for creationism"... A lot of outright lies and misrepresentation of initial indicators on their part. –  Brightblades Jun 5 '12 at 14:58
I like how applying new techniques to old results that looked kinda like nonsense and getting new results that do make sense is apparently a bad thing. –  Tacroy Jun 5 '12 at 16:43
I note that all the dates in the post predate the on-set of genetic drift dating and the the genetic clock agrees well with the up-to-date radiometric results. In other words, the claim is focusing on errors long corrected to try to throw doubt on to a process which finds its strength in its ability to correct itself. –  dmckee Jun 5 '12 at 18:17
@Tacroy, It isn't a bad thing, it just calls into question the accuracy of the fossil record. How does one know that one fossil is older than another, and that one species evolved into another? (K-Ar dating) If the fossil doesn't fit the evolutionary model, because the fossil has a brain capacity that is too large 750 cc), then the dating is called into question instead of the evolutionary model. Is the evolutionary model not falsifiable? How can you falsify the model if the fossils that might disprove it , have samples that are tainted. –  user1873 Jun 5 '12 at 19:22
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1 Answer

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 Leaky 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 triumphs 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.

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 Leaky'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 of which 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, Leaky admits to his mistake about the initial date and the KBS Tuff.

Leaky says the date is wrong

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 Leaky et al does figure out the problem with the Tuff.

Tuff Layers, with inversions

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 Leaky 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 Leaky:

Revised homo family tree

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.

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