flax
Richard Dawkins on the Shroud
In September of 2009, Richard Dawkins, in his new book, The Greatest Show on Earth: The Evidence for Evolution, seemed to trip over many of these points, directly or by implication:
[Carbon dating] has revolutionized archaeological dating. The most celebrated example is the Shroud of Turin. Since this notorious piece of cloth seems mysteriously to have imprinted on it the image of a bearded crucified man, many people hoped it might hail from the time of Jesus. It turns up in the historical record in the mid-fourteenth century in France, and nobody knows where it was before that. It has been housed in Turin since 1578, under the custody of the Vatican since 1983. When mass spectrometry made it possible to date a tine sample of the shroud, rather than the substantial swathes that would have been needed before, the Vatican allowed a small strip to be cut off. The strip was divided in three parts and sent to three leading laboratories specializing in carbon dating, in Oxford, Arizona and Zurich. Working under conditions of scrupulous independence—not comparing notes—the three laboratories reported their verdicts on the date when the flax from which the cloth had been woven died. Oxford said ad 1200, Arizona 1304 and Zurich 1274. These dates are all—within normal margins of error—compatible with each other and with the date in the 1350s at which the shroud is first mentioned in history. The dating of the shroud remains controversial, but not for reasons that cast doubt on the carbon-dating technique itself. For example, the carbon in the shroud might have been contaminated by a fire, which is known to have occurred in 1532. I won’t pursue the matter further, because the shroud is of historical, not evolutionary, interest. It is a nice example, however, to illustrate the method, and the fact that, unlike dendrochronology, it is not accurate to the nearest year, only to the nearest century or so. [Emphasis mine]
Dawkins is either clueless or selective. One wonders if he even checked Wikipedia. On the matter of the historical record he implies that the absence of evidence is itself evidence or as Donald Rumsfeld famously put it, “absence of evidence is not evidence of absence.” He was trying to justify his belief that there were weapons of mass destruction in Iraq.
Skeptics Dictionary More Closely
It helps to look a bit more closely at what Carroll writes in the Skeptics Dictionary:
Of course, the cloth might be 3,000 or 2,000 years old, as Rogers speculates, but the image on the cloth could date from a much later period. No matter what date is correct for either the cloth or the image, the date cannot prove to any degree of reasonable probability that the cloth is the shroud Jesus was wrapped in and that the image is somehow miraculous. To believe that will always be a matter of faith, not scientific proof. (4)
First of all, Rogers did not speculate that it was 3,000 or 2,000 years old. What Rogers argued was that the lack of vanillin in the fabric of the shroud was a serious challenge to the carbon dating. Flax, like the vanilla bean, contains vanillin. Over time, a very long time, it decomposes. How long it takes, depends on temperature. Given a plausible range of average ambient temperatures during the life of the cloth, chemical kinetics demonstrates that the cloth is somewhere between 1,300 and 3,000 years old and not about 700 years old as the carbon dating suggested. Rogers carefully demonstrated that.
Second of all, we need not ascribe miraculous causation to the image, as Carroll suggests, to infer at some level of certainty that it might be the shroud Jesus was wrapped in. There might be, as Rogers and other think, a perfectly natural chemical explanation for the images. The suggestion that the image might be from a much later period is interesting but improbable. This is what Wilson thought. We will address this possibility, but not yet. We have some work to do in understanding the science and the history, none of it very difficult and all of it entertaining, before we tackle this.
Raking Light
By shining a beam of light from very close to the cloth, almost parallel to the surface, the ridges in the twill become very pronounced. The light exaggerates highlights and shadows. You can see the effect with a bright flashlight and a pair of denim jeans. You may also notice on the jeans, otherwise unnoticed wrinkles and creases become quite visible, as well. This use of near-parallel lighting, called raking light, is a valuable technique in the forensic examination of fabrics and other rough surfaces. Raking light is also used in the restoration of paintings to enable a restorer to more clearly see the exact nature of the artist’s brushstrokes.
No brushstrokes were found in the images on the shroud, but creases and wrinkles were easily detected. It’s the nature of linen to wrinkle and retain creases. The flax fibers that are twisted together to form linen thread or yarn, like all plant fibers, is a cellulose material, a polymer made up of long chains of molecules of carbon, oxygen and hydrogen atoms. They form up in long strands, side by side but staggered, bound together by hydrogen bonds and thus forming long fibers. When linen is wet with water, the water molecules (H2O) destabilize some of the existing bonds, but not enough of them to significantly weaken the fibers. When the cloth is allowed to dry, and the water molecules evaporate into the air, new bonds form but not always where they were before. This causes wrinkles and small creases. You can think of wrinkles as miniature rolling hills and creases as like jagged cliffs and deep gulches. You don’t need to actually wet a piece of linen to create wrinkles and creases. Just increases followed by decreases in humidity levels is enough.
The Making of Linen
Here is roughly what we know: After harvesting flax plants, the long stems are threshed to remove seeds, leaves and roots so that only a stalk remains. In a step called retting, the stalks are then placed in pools of water or streams to rot away most of the stems while leaving the cellulose fibers intact. The remaining material was then scotched, which means simply that it was scraped to remove remaining woody material from the stalk. Then it was hackled or combed to separate various grades of fibers. The finest, longest strands are used for what Pliny called bysus, a word derived from the biblical words bus and shesh, meaning fine linen. (Linen is also called peshet and pishta in the Old Testament and kittan in the 2nd century Mishnah.)
Only two steps remain before weaving. The first is to twist or spin dozens of the fibers together into thread. The next is to bleach the thread, which is often tan or gray.
The Decomposition of Vanillin
Vanillin is of interest to us because it is found in the lignin component of newly harvested flax fibers. Over time, a very long time, vanillin decomposes and disappears from the fibers. For instance, if you leave a piece of linen lying around—that hasn’t had all its lignin removed by modern bleaching—for about 650 years and you then examine it for vanillin, you will find that nearly two-thirds of the vanillin has disappeared. Leave it around for another 650 years and it is all gone, or nearly so. Temperature affects the process but not drastically within the range of normal ambient temperatures. In other words, under normal conditions, it takes at least 1300 years for all of the vanillin to disappear. Raymond Rogers noticed that . . .
A linen produced in A.D. 1260 [the earliest possible date that the cloth could have been produced according to the 1988 carbon dating] would have retained about 37% of its vanillin in 1978. . . . 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. (37)
Flax Fibers
Flax fibers, from which the linen thread of the shroud is made, vary in thickness as well. But on average they are about 10 to 20 microns thick or about one-tenth to one-fifth the thickness of a typical human hair. Twist or spin together somewhere between 70 and 120 of these fibers and you get a single thread of the sort used for weaving the shroud’s linen fabric.
The layer or cell wall is thinner still. We said that Rogers had found an impurity layer and we might wonder how thick that is. Rogers had measured the thickness of the layer in places and found thickness ranging between 160 and 600 nanometers. That’s not microns; that is nanometers. Not millionths of a meter but billionths. That standard human hair that is 100 microns thick is 100,000 nanometers thick. If you could possibly slice that human hair lengthwise, from end to end, into 166 very thin slices, each slice would be as thick as the thickest coating Rogers found. And the thinnest coating Rogers found was about one-fourth of that. The coating, in most cases is about as thin as the wall of a soap bubble drifting through the air. It is as thin as the glare proof coating on modern eyeglasses. Take a coin out of your pocket. Polish it between your fingers and thumb. It has a coating of oil on it as thick as the coating Rogers believes he has found on the shroud’s fibers. You can’t see it but it is there.
Hair is 100,000 nanometers thick. A flax fibers is about 15,000 nanometers thick. The impurity layer on the shroud is about 600 nanometers thick. The layer is only ten percent of the diameter of a red blood cell. That is thin, plain and simple.
5730
As soon as a plant dies it stops taking on carbon dioxide. And animals stop taking in any form of carbon. That means that the slices of tomato in your sandwich are only half as radioactive after 5730 years. That means that if we could count the regular carbon atoms and the carbon 14 atoms and calculate the ratio, we could figure out how old something is. And that means that means we should be able to figure out how old the shroud is because the linen cloth would have been made from newly harvested flax plants. That is, we could do so if we knew how much carbon 14 was produced year-by-year throughout history.
The astonishing thing is that the production of new carbon 14 atoms in the upper atmosphere and the decay of carbon 14 takes place at about the same rate. It’s uncanny. It is one of those amazing balancing acts that takes place in nature. In a sense, for every C14 atom that dies another one is born. It isn’t exact but it close enough. Scientists are quite certain that it has been this way for tens of thousands of years, perhaps millions of years. It does vary a bit year by year and estimated adjustments have been calculated by dating the rings of very old trees. Well, that is until we started exploding nuclear bombs when we significantly upset this one of many, many balances of nature.
Garza-Valdes and the Scanning Electron Microscope
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 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 (they do exist on some ancient objects) obtain their carbon material from the host (fibers in this case) and not from the atmosphere, hence they do not significantly alter the C14 dating. Even if they could alter the date, the amount of material needed would need to be significant. On this point, Gove took exception with the bioplastic theory and agreed.
Cotton
Several years earlier, a textile expert, Gilbert Raes (for whom the Raes corner is named), had been permitted to cut away a small fragment of the shroud. In it he found cotton fibers. Rogers confirmed the existence of embedded cotton fibers and noted that such cotton fibers are not found in other samples from anywhere else on the shroud. Cotton fibers were sometimes incorporated into linen threads during later medieval times, but not earlier, and not even as early as the carbon 14 range of dates. This, along with the dyestuff, suggested some sort of alteration or disguised mending.
Rogers also noted that fibers in the Raes material contained less lignin than the rest of the shroud. Lignin is a chemical compound found in plant material including flax, the plant from which linen fibers are sourced. The most plausible explanation for this difference was that material in this area contained threads that had been bleached more efficiently. It was already known from the shroud’s faint variegated appearance that the shroud’s thread was probably bleached before weaving, probably with potash. This is not an exacting method and thus some hanks of yarn were whiter than others. As the cloth aged and naturally yellowed, the variegation became more pronounced, as can be seen in contrast-enhanced photographs. This form of ancient bleaching removed very little lignin.
Arguably, from a historical point of view (but not a scientific one) the linen cloth used for the shroud was not produced in medieval Europe. Even by the timeframe suggested by the radiocarbon dating, linen was “field bleached” after weaving. And it removed most of the lignin.
Lignin and Vanillin
Lignin is significant not only because of the observed disparities but because it is the raw source for vanillin. Vanillin is produced from lignin by thermal decomposition. Rogers knew that if the shroud had been correctly carbon dated, the cloth should produce measurable amounts of the aromatic substance. Found in medieval linen, but not in much older cloth, vanillin diminishes and disappears with time. Rogers discovered that there was no detectable vanillin in the flax fibers of the main part of the shroud just as there is no vanillin in the linen wrapping from the Dead Sea Scrolls. There was, however, vanillin in the corner from which the carbon 14 samples were taken. He concluded that the main part of the shroud and the carbon 14 sample had a different age.
If the cloth had been manufactured in 1260, the earliest date suggested by carbon dating, it should have retained about 37% of its vanillin. Paraphrasing Rogers, Ball writes, “Let’s call it somewhere around the middle of that range, which puts the age at about 2,000 years. Which can mean only one thing… (ellipsis are Ball’s).
While this is not an accurate method for determining the age of linen because it depends on the average storage temperature over many centuries, it is useful as a sniff test for checking carbon 14 dating. Not only does this information verify that the carbon 14 sample is chemically different from the rest of shroud, it demonstrates that the carbon 14 sample probably contained much newer material than the rest of the shroud.
Robert Villarreal from the Los Alamos National Laboratory
In a presentation The Ohio State University’s Blackwell Center, Los Alamos National Laboratory (LANL) chemist, Robert Villarreal, disclosed new findings showing that the sample of material used in 1988 to Carbon dating could not have been from the original linen cloth because it was cotton. According to Villarreal, who lead the LANL team working on the project, thread samples they examined from directly adjacent to the sampling area were “definitely not linen” and, instead, matched cotton. Villarreal pointed out:
the [1988] age-dating process failed to recognize one of the first rules of analytical chemistry, that any sample taken for characterization of an area or population must necessarily be representative of the whole. The part must be representative of the whole. Our analyses of the three thread samples taken from the Raes and C-14 sampling corner showed that this was not the case.
Villarreal also revealed that, during testing, one of the threads came apart in the middle forming two separate pieces. A surface resin, that may have been holding the two pieces together, fell off and was analyzed. Surprisingly, the two ends of the thread had different chemical compositions, lending credence to Rogers’ finding in Thermochimica Acta.
After conducting analysis at high vacuum with the ToF-SIMS, the “spliced thread” broke into three distinct pieces; a fuzzy end (Region 1), a tight woven end (Region 2), and a micro-sized circular cocoon-shaped brown crust that seemed to be connecting the two end pieces. The ToF-SIMS results were the first to show that the spectra from the two ends were similar to cotton rather than linen (flax) and the Spectroscopist recommended that the next analysis should be with the FTIR instrument. After several scans of individual fibers or strands, the FTIR data showed that the two ends (Region 1 and 2) were definitely cotton and not linen (flax). The crust appeared to be an organic-based resin, perhaps a terpene species, with cotton as a main sub-component. After showing the FTIR data to Barrie Schwortz and Sue Benford, they were quite surprised at the results and decided to send me two other pieces of thread (No. 7 and 14) that were from the same sampling area and that had been in John Brown’s Lab in Marrietta, Georgia.
The results of the FTIR analysis on all three threads taken from the Raes sampling area (adjacent to the C-14 sampling corner) led to identification of the fibers as cotton and definitely not linen (flax). Note, that all age dating analyses were conducted on samples taken from this same area. Apparently, the age-dating process failed to recognize one of the first rules of analytical chemistry that any sample taken for characterization of an area or population must necessarily be representative of the whole. The part must be representative of the whole. Our analyses of the three thread samples taken from the Raes and C-14 sampling corner showed that this was not the case. What was true for the part was most certainly not true for the whole. This finding is supported by the spectroscopic data provided in this presentation.
The recommendations that stem from the above analytical study is that a new age dating should be conducted but assuring that the sample analyzed represents the original main shroud image area, i.e. the fibers must be linen (flax) and not cotton or some other material. It is only then that the age dating will be scientifically correct.
Paints or Dyes
Nowhere on the Shroud are there sufficient concentrations of paints or dyes to form a visible image. Iron oxide might have formed by retting flax in iron rich water in the production of linen. And just as one finds minuscule particles of iron oxide (rust) in airborne dust, so too might mercuric sulphide be present in dust that settled on the Shroud, once kept in churches and cathedrals with frescoed walls and ceilings. There is another possibility that might well explain the presence of trace amounts of paint particles on the Shroud. Many painted copies of the Shroud were produced. It was, after all, a revered relic. We know from history of a practice whereby artists would touch or rub their paintings on the Shroud for sanctification.
Richard Dawkins
[Carbon dating] has revolutionized archaeological dat-ing. The most celebrated example is the Shroud of Tu-rin. Since this notorious piece of cloth seems myste-riously to have imprinted on it the image of a bearded crucified man, many people hoped it might hail from the time of Jesus. It turns up in the historical record in the mid-fourteenth century in France, and nobody knows where it was before that. It has been housed in Turin since 1578, under the custody of the Vatican since 1983. When mass spectrometry made it possible to date a tine sample of the shroud, rather than the sub-stantial swathes that would have been needed before, the Vatican allowed a small strip to be cut off. The strip was divided in three parts and sent to three leading laboratories specializing in carbon dating, in Oxford, Arizona and Zurich. Working under conditions of scrupulous independence—not comparing notes—the three laboratories reported their verdicts on the date when the flax from which the cloth had been woven died. Oxford said ad 1200, Arizona 1304 and Zurich 1274. These dates are all—within normal margins of error—compatible with each other and with the date in the 1350s at which the shroud is first mentioned in his-tory. The dating of the shroud remains controversial, but not for reasons that cast doubt on the carbon-dating technique itself. For example, the carbon in the shroud might have been contaminated by a fire, which is known to have occurred in 1532. I won’t pursue the matter further, because the shroud is of historical, not evolutionary, interest. It is a nice example, however, to illustrate the method, and the fact that, unlike den-drochronology, it is not accurate to the nearest year, only to the nearest century or so. [Emphasis mine]