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Carbon Dating

Carbon 14 Dating On Shroud of Turin Were Botched 2008

A January 20, 2005 article in the scholarly, peer-reviewed scientific journal Thermochimica Acta (Volume 425, pages 189-194, by Raymond N. Rogers, Los Alamos National Laboratory, University of California) makes it perfectly clear: the carbon 14 dating sample cut from the Shroud in 1988 was not valid. In fact, the Shroud is much older than the carbon 14 tests suggested. 


Photomicrograph of fibers from middle of carbon 14 sample. It is chemically unlike the rest of the shroud. That is a problem.

No matter what any one of us may believe about the Shroud’s authenticity, we can no longer say that carbon 14 dating proves medieval origins; for the tests in 1988 were botched. For those who after 1988 continued to believe that the Shroud was the genuine burial cloth of Jesus, a winter of ridicule and doubts has ended. For all who use carbon 14 dating to study all manner of ancient objects, a period of careful reassessment is just beginning.

There are, in understanding what went wrong, important lessons that will ripple through archeology, anthropology, forensics and science lecture halls whenever and wherever carbon 14 dating is discussed. Students will ask why a single sample from a suspect corner was used. They will wonder why protestations from experts in the Shroud’s chemistry were ignored. The will ask why documented data was not considered. They will talk about the clues of material intrusion that were simply ignored.

Material intrusion is well known in the application of carbon 14 dating. A classic example is to be found in the dating of peat bogs. Very old bogs often contain miniscule roots from newer plants that grew in the peat. The roots of these plants, sometimes having decomposed, are nearly indistinguishable from the older peat. What ends up being tested is a mixture of old and new material which produces an average, meaningless carbon 14 age.  No one seemed to consider, in 1988, that material intrusion might be a serious problem with the Shroud of Turin carbon 14 dating even though clues were there.

Photomicrograph of fibers from the center of the radiocarbon sample in water. Gum material is swelling and detaching from fibers. Chemical tests show that dye is yellow alizarin from madder root complexed with alum, a common mordant. Several cotton fibers are also visible. Cotton, alizarin and gum are only found in the C14 sample area of the shroud.

The 1988 carbon 14 dating failure will not be ignored; for how does one ignore such a famous example. It should not be ignored because of the lessons to be learned. It cannot be ignored so long  students raise hands and Google-check lecture notes. It should not be ignored when journalists and authors write about carbon 14 dating. There are textbooks, encyclopedias and many websites to be updated.

This is not a condemnation of carbon 14 dating. It is an extraordinary technology that with uncanny precision can count the approximately one in a trillion carbon 14 isotopes that exist compared to the more common carbon 12 and carbon 13 isotopes; isotopes that exist in all living material and material that once was living. In the case of the Shroud it was the fibers of flax plants from which linen thread is made. When a plant or animal dies it no longer absorbs carbon.  And so begins a process that can be measured. Because carbon 14 is radioactive, it decays.  And because scientists know the rate of decay, measured in half-lifes, they can calculate how old something is. The current state of the technology is useful for dating things younger than 50,000 years. For material that is only a few thousand years old, carbon 14 dating is very accurate and very reliable.

Because of the carbon 14 dating, the Shroud of Turin, a religious object important to Christians of many traditions (Catholic, Orthodox, Anglican, Protestant and Evangelical;  conservative and liberal alike) has been cast into the spotlight of secular science. It is not because the Shroud is famous, although it is. It is because the 1988 carbon 14 dating was made famous. And because it was made famous, and because it will now be discussed, the related science of the Shroud will also get attention:

  • the peculiar nano-scale carbohydrate film that coats some of the fibers, a coating that holds within its chemical makeup the conjugated complex carbon bonds of the images;

  • the forensics of the blood that, because it is ancient, should be black but is red for good chemical reasons;

  • the ancillary age-related data about the depletion of vanillin from the lignin of the flax (cellulose) fibers, the depletion that indicates that the Shroud is much older than the carbon 14 assigned date range of 1260 to 1390.

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From the article in Thermochimica Acta: "A linen produced in A.D. 1260 would have retained about 37% of its vanillin in 1978. The Raes threads, the Holland cloth [shroud's backing cloth], and all other medieval linens gave the test for vanillin wherever lignin could be observed on growth nodes. The disappearance of all traces of vanillin from the lignin in the shroud indicates a much older age than the radiocarbon laboratories reported."

Famous Carbon 14 Dating

The carbon 14 dating of the Shroud is famous because those who had difficulty accepting the results were ridiculed and called fanatics by tough-minded skeptics. On public television, a prominent Oxford scientist, Edward (Teddy) P. Hall, who played a significant role in exposing the Piltdown man hoax and who participated in the carbon 14 dating of the Shroud, expressed his views openly: “We have shown the Shroud to be a fake. Anyone who disagrees with us ought to belong to the Flat Earth Society.”

The carbon 14 dating of the Shroud of Turin is famous because it spawned so many conspiracy theories posing as history. John Dominic Crossan, the famed Jesus Seminar scholar, proposed that someone in medieval times was crucified by a crafter of fake relics in order to produce the Shroud. Others proposed that Leonardo da Vinci created it — anew, it turns out, since the Shroud was well known in Europe a century before Leonardo was born. Walter McCrone, a renowned microscopist, who examined some borrowed fibers from the Shroud, claimed that the images were painted — just as a medieval bishop, Pierre d’Arcis, had claimed in 1389. The painting claims are preposterous because other unimpeachable chemical studies prove that the images were not painted.

The carbon 14 dating of the Shroud is famous because Nature, the prestigious international weekly journal of science, published an article about the tests. It was coauthored by no less than twenty-one scientists from the University of Oxford, the University of Arizona, the Institut für Mittelenergiephysik in Zurich, Columbia University, and the British Museum. The conclusion in Nature was clear:

The results of radiocarbon measurements at Arizona, Oxford and Zurich yield a calibrated calendar age range with at least 95% confidence for the linen of the Shroud of Turin of AD 1260 – 1390 (rounded down/up to nearest 10 yr). These results therefore provide conclusive evidence that the linen of the Shroud of Turin is mediaeval.

The carbon 14 dating of the Shroud is famous because so many people doubted the results, doubted such prestigious scholarly, scientific authority? Partly, it was because the Shroud of Turin is a religious object; millions believe it is the real thing, the burial cloth of Jesus of Nazareth. Partly, it was because there was a lot of other evidence that argued that the Shroud was plausibly real. And partly, it was because there were persistent clues that the tests were invalid. The faithful believers, the scientists and the historians who were weighing other evidence were arguing that something seemed wrong. They would, in the years following 1988, try to figure out what that was.

Why Might the Carbon 14 Dating Be Wrong

Various theories bubbled up, were exposed to scrutiny, and burst. Some suggested that the snippet cut from the shroud for testing was from a section of the shroud that had been damaged and rewoven. Others suggested that the sample was contaminated with residue from a damaging fire in 1532. But the scientists who conducted the carbon 14 tests refuted these suggestions. They denied that the sample was taken from a damaged area and they argued that any residue from the fire would have been removed during the sophisticated cleaning process that precedes actual testing.

Leoncio Garza-Valdes, a Texas pediatrician and amateur archeologist, and Stephen Mattingly of the University of Texas offered another suggestion. They claimed that they found an organic bioplastic contamination on the Shroud that would not have been removed with the cleaning process that the labs had used.

The bioplastic idea gained traction among many Shroud researchers when Harry E. Gove, a nuclear physicist at the University of Rochester who designed the carbon-dating methods used on the Shroud, gave tentative support to Garza-Valdes and Mattingly. Jeffery L. Sheler, writing in the July 24, 2000, issue of U.S. News & World Report, quotes Gove: 

"There is a bioplastic coating on some threads, maybe most."  Gove goes on to say that if there is a sufficient quantity of bioplastic it "would make the fabric sample seem younger than it should be" in the carbon 14 dating.

But the bioplastic idea came up short. Garza-Valdes had said: "With a scanning electron microscope, I found the fibers were completely covered by the bioplastic coating (polyhydroxyalkanoate) and by many colonies of fungi which usually thrive on this polymer…"  But other scientists find this statement flawed and this probably explains why the bioplastic idea was not be published in a peer reviewed journal. For one thing, there is no way to determine the definitive composition of an organic material by scanning electron microscope.  Garza-Valdes’  provided photomicrograph showing a "filamentous cell" that turned out to be an ultimate cell from the flax structure. Furthermore, it is well known that such polymers obtain their carbon material from the host (fibers in this case) and not from the atmosphere, hence they would not significantly alter the carbon 14 dating. Even if they could alter the date, the amount of material needed  would to be significant. On this point, Gove took exception with the bioplastic theory by explaining that the quantity of biological material would be very significant.

Ray Rogers explains:

Even assuming that the coating formed all at once in the 20th Century during a high­fallout time, when bomb-produced 14C was high, an observable error in the age determination would require the addition of a significant amount of material to the surface of the Shroud.

Because significant material could be easily detected, fibers from the Shroud were examined at the National Science Foundation Mass Spectrometry Center of Excellence at the University of Nebraska. Pyrolysis-mass-spectrometry examination failed to detect any form of bioplastic polymer on fibers from either non-image or image areas of the Shroud. Additionally, laser-microprobe Raman analysis at Instruments SA, Inc. in Metachin, NJ, also failed to detect any bioplastic polymer. 

As it turns out, those who suggested that the carbon 14 samples were from a rewoven area were right. This is what was reported in Thermochimica Acta on January 20, 2005.

Thermochimica Acta is not the sort of journal you will find in the reading room of public libraries. It’s a journal about thermoanalytical and calorimetric science. It is mainly for chemists. It is a peer reviewed journal which means that articles are carefully examined by other scientists to ensure that the science is true, methods are sound, and all explanations and conclusions are completely free of logical fallacies. Peer review, an exacting process of challenge and correction, is the normal way that scientists announce their findings. Rogers’ findings were that the samples were invalid and indeed the Shroud is significantly older than the carbon 14 dating suggested. 

Carbon 14 Dating Scientists Fooled

When the Piltdown man hoax was uncovered in 1953, sophisticated chemical analysis techniques, developed in part by Teddy Hall, showed that skull fragments and other bone pieces had been expertly dyed to look older and match each other. This was done to fool people into thinking the bones were very old. People were fooled and many thought that the Piltdown man might be the missing link. 

In the case of the Shroud of Turin, it was threads were dyed to look older and to match other threads.  But it wasn’t the threads of the Shroud itself that were dyed. It was a small area in one corner of the Shroud where some mending threads had been dyed to look like the rest of the age-yellowed Shroud. Chemical analysis proves this. There is absolutely no doubt about that. 

In the case of the Shroud it was the carbon 14 testers that were fooled. And they should not have been fooled. There were clues that warranted investigation:

  • In 1973, Gilbert Raes of the Ghent Institute of Textile Technology was given permission to remove a small sample from a corner of the Shroud. In the sample he found cotton fibers.  It might have been that the cotton was leftover fibers from a loom that was used for weaving both cotton and linen cloth. It might have been that the Shroud was exposed to cotton much later, even from the gloves used by scientists. However, when later he examined some of the carbon 14 samples, he noticed that cotton fibers, where found, were contained inside threads, twisted in as part of the thread. It is important to note that cotton fiber is not found anywhere else on the Shroud.

  • P.H South, while examining threads from the sample on behalf of the Oxford University Radiocarbon Dating Laboratory found similar indication of cotton. To him it seemed like material intrusion. In an article entitled "Rogue Fibers Found in Shroud," published in Textile Horizons in 1988, South write of his discovery of "a fine dark yellow strand [of cotton] possibly of Egyptian origin, and quite old . . . it may have been used for repairs at some time in the past, or simply bound in when the linen fabric was woven." 

  • Teddy Hall, of the Oxford radiocarbon dating laboratory, also noticed fibers that looked out of place.

  • Giovanni Riggi, the person who actually cut the carbon 14 sample from the Shroud stated: "I was authorized to cut approximately 8 square centimetres of cloth from the Shroud…This was then reduced to about 7 cm because fibres of other origins had become mixed up with the original fabric …"  (italics mine)

  • Giorgio Tessiore, who documented the sampling, wrote:  “…1 cm of the new sample had to be discarded because of the presence of different color threads.” (italics mine)

  • Al Adler of Western Connecticut State University found large amounts of aluminum in yarn segments from the radiocarbon sample area, up to 2%, by energy-dispersive x-ray analysis. The question should have been asked: why aluminum?  It is not found elsewhere on the Shroud.

In the years following the carbon 14 dating, in the years when careful reexamination seemed warranted, other compelling reasons to be suspicious emerged:

· Chemical analysis of the lignin of the flax fibers did not test positive for vanillin. If the Shroud was medieval, it should have. Vanillin disappears slowly from the lignin in flax fibers and all of it has disappeared except in the immediate vicinity of the carbon 14 sample. This indicated that the cloth was much older than the carbon 14 dating suggested and that the carbon 14 sample area was certainly chemically different. 

image

From the article in Thermochimica Acta: "A linen produced in A.D. 1260 would have retained about 37% of its vanillin in 1978. The Raes threads, the Holland cloth [shroud's backing cloth], and all other medieval linens gave the test for vanillin wherever lignin could be observed on growth nodes. The disappearance of all traces of vanillin from the lignin in the shroud indicates a much older age than the radiocarbon laboratories reported."

· In 1973, Gilbert Raes, of the Ghent Institute of Textile Technology, had cut a small piece from a corner of the Shroud. One part of it contained cotton fibers among the flax fibers while another part of it did not. Rogers, following up on Raes’ examination of the 1973 sample, also found cotton. Moreover, Rogers found dyestuff and spliced threads that were not found elsewhere on the Shroud.  It is significant to note that the carbon 14 sample was taken from a spot adjacent to the Raes sample.

· In 2000, M. Sue Benford and Joseph G. Marino, working with a number of textile experts, examined documenting photographs of the carbon 14 sample and found evidence of expert reweaving that joined disparate materials almost at the middle of the sample. The consensus was that there was about 60% new material and 40% original material in the sample. If that is the case, and if the repair was made in the early 1500s as history suggests, then according to Ron Hatfield of Beta Analytic, a first century date for the cloth is reasonable.

· In 1997, Remi Van Haelst, a Belgium chemist, conducted a series of statistical analyses that strongly challenged the veracity of the conclusions of the carbon 14 dating. Significantly, he found serious disparities in measurements between the three laboratories and between the sub-samples (various tests and observations performed by the labs). Bryan Walsh, a statistician and physicist, examined Van Haelst’s work and further studied the measurements. The essential conclusions were that the samples, and indeed the divided samples used in multiple tests, contained different levels of the carbon 14 isotope. The differences were sufficient to concluce that the sample were non-homogeneous and thus of questionable validity. Walsh found a significant relationship between various sub-samples and their distance from the edge of the cloth. If indeed a patch was rewoven into the cloth and if the joining of old and new material ran at an angle through the sample cuttings (as it appears to do so) then all this makes sense.

Carbon 14 Dating Samples Studied

In December 2003, Rogers was able to obtain material from the actual carbon 14 sample cutting used for testing in 1988. This material had been saved from the center of the carbon 14 samples before they were distributed to the carbon 14 laboratories. What Rogers found proved that the sample was bad. He found threads encrusted with a plant gum containing alizarin dye; a dye that is extracted from Madder root. Some of the dye was complexed with a common mordant, alum (hydrous aluminum oxide). He found cotton fibers. And he found spliced threads. The dyestuffs, the cotton fibers and spliced threads are not found elsewhere on the Shroud.

In Thermochimica Acta, Rogers wrote:

The combined evidence from chemical kinetics, analytical chemistry, cotton content, and pyrolysis/ms proves that the material from the radiocarbon area of the shroud is significantly different from that of the main cloth. The radiocarbon sample was thus not part of the original cloth and is invalid for determining the age of the shroud.

Rogers doesn’t simply prove that the sample was invalid. Rogers provides alternative ways to understand that the Shroud was certainly older than the 1988 carbon 14 dating debacle implied.

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