About a week ago I received the hardcopy of the December 2007 "Shroud Newsletter" of the British Society for the Turin Shroud (BSST)
[Left: Electron micrograph of a Gundelia tournefortii pollen grain from the Max Frei collection, Prof. Avinoam Danin.]
containing my paper, "A proposal to radiocarbon-date the pollen of the Shroud of Turin."
That last link is to a PDF of my paper which has now been webbed, along with that latest BSST newsletter, on Barrie Schwortz' Shroud.com. It is actually the full word-processed manuscript I submitted, converted to PDF, whereas the hardcopy version in the Newsletter has been slightly abbreviated. I will later blog in my January Shroud News about the new items on Barrie's site, including those in the BSST Newsletter.
However, now I will comment on my own paper (its words bold), expanding on my reasonings in a way that I could not in the paper itself, given the space constraints within the BSST Newsletter (my thanks to Mark Guscin its editor, for the generous allocation of space he did give my paper).
A major area of Shroud of Turin studies over the past half-century has been radiocarbon-dating the Shroud's linen ... A potentially major new line of research ... is radiocarbon-dating the pollen of the Shroud of Turin. On 23 May 2007, I emailed a leading sindonologist, "Early this morning, while still in bed half-asleep, the thought came to me, Why not radiocarbon date the [Shroud's] pollen?" By then I had read a lot of Shroud books and articles on carbon-dating the Shroud's linen, but it suddenly occurred to me that I had not read anything about carrying out the same dating test on the Shroud's pollen. After all, pollen is just another part of a plant as the flax that linen is made from, and therefore it contains the same carbon, including carbon-14. I found out from this and other Shroud experts that I later emailed that, while the idea had occurred to some in the Shroud pro-authenticity community, it apparently had never been publicly proposed.
One reason given was that it was thought that too many of the precious pollen grains would have to be destroyed in the process and it had not been realised that advances in AMS radiocarbon dating had made dating of single pollen grains possible (see below). Another reason may be that in science it is often that an outsider first thinks of a new approach, or first takes it seriously enough to publicly propose it, because it is `outside the box' of what researchers in that field are concentrating on.
I received confirmation that my proposal was sound when I later found that the idea of radiocarbon-dating the Shroud's pollen, as a check on the 1988 linen dating, had briefly been mentioned in the mainstream scientific literature:
"Microgram level 14C soot studies have already been successful in Greenland snow; and pollen studies hold great promise for ice core dating, and perhaps even for dating the pollen found by Max Frei on the Turin Shroud. ... An important measurement issue for ice core pollen relates to the amount needed for a given dating precision. To give a rough estimate: assuming 50 ng carbon per pollen grain, a pollen age of 2000 years, and 5% Poisson imprecision (s ~ 400 years); one would need to collect about 100 pollen grains. This might be accomplished in a few hours, using the `hand picking' microscope technique ... Molecular dating" of the pure cellulose fraction of the Shroud, or of the associated pollen, could furnish an interesting consistency test for the published radiocarbon date. It would be especially interesting to put a `time stamp' on pollen whose point of origin has already been ascribed to a location 10 km to 20 km east and west of Jerusalem ... . Such measurements are made feasible by the reduction of requisite sample sizes by a factor of ten or more, from what AMS 14C dating required sixteen years ago. The question of noncontemporaneous fiber from 16th Century repairs, for example, could be addressed by new 14C measurements on just 100 mg of fibers (~50, 1 cm linen fibers) from the main part of the Shroud. The expected standard uncertainty would be equivalent to approximately 120 radiocarbon years ..." (Currie, L.A., "The remarkable metrological history of radiocarbon dating [II] ," Journal of Research of the National Institute of Standards and Technology, Vol. 109, No. 2, March 1, 2004. PDF).
Advantages of radiocarbon-dating the Shroud's pollen
Pollen is less subject to contamination than linen. ... pollen has a non-porous external shell or exine comprised of a tough organic polymer, sporopollenin, which ... is one of the most decay- and chemical-resistant substances known. ... This makes pollen extremely resistant to degradation by microorganisms ... This is a major advantage of carbon-dating pollen compared with linen. The fundamental assumption of carbon-dating is that what is being dated is the original carbon that was present when the plant or animal died, and not extraneous carbon that has subsequently entered the sample.
However, because linen is very porous, and comprised of multiple spiral microfibrils, like a rope, it is easily contaminated by microorganism and difficult to remove by pretreatment, without destroying the sample. By contrast, pollen's outer shell or exine (which is what is usually meant by "pollen" in this context-the soft pollen interior or intine, usually decomposes rapidly, leaving only the exine), is extremely non-porous, and therefore largely free from contamination. And because the exine is very hard and chemical-resistant, it can be subjected to far stronger pretreatments to remove what little contamination there is, without destroying the sample. The likelihood is therefore very high that the carbon that is dated is only what was there when the pollen grain's parent plant died (i.e. in the case of linen the flax was harvested).
Pollen is richer in carbon than linen. The carbon content of pollen's sporopollenin-rich exine is about 90% compared to about 50% ... of ... flax. This is a bonus because pollen grains are extremely tiny, as can be seen by the less than 5 µm (5 micrometres, or 5 thousandth of a millimetre) diameter of a Gundelia tournefortii pollen grain, which is one of the larger pollens!
The accelerator mass spectrometry (AMS) method ... can accurately date ... single pollen grains. This technological advance is what makes radiocarbon-dating the pollen of the Shroud feasible, at least in principle.
Pollen contains geographic information. Pollen grains vary in size, shape and surface features ... unique to the genus or species of its parent plant. Therefore, those ... which are native to a particular region can indicate where the Shroud has been. >This is the basis of forensic palynology. A cloth picks up pollen from its environment and if it travels through a series of different botanical regions, as is proposed of the Shroud by Ian Wilson's Eddessa Cloth-Shroud theory (see part #2), pollens from plants unique to those regions should document a historical record of that cloth's journey.
... Frei identified 57 different kinds of plants from pollen samples he had collected from the Shroud ... native to Palestine, Turkey, as well Europe. ... all Frei's identifications were accurate at the genus level. ... While species level identification would be better, genus-level identification should still be sufficient, especially considering overall assemblage of non-European pollen genera on the Shroud, to decisively test Wilson's theory.
It is here assumed that only Shroud pollen grains in the Max Frei collection will be radiocarbon-dated, at least initially ... permission of the Pope or the Archbishop of Turin is not required. It is simplest to first test the pollen in the Frei collection because it is private property and because pollen in that collection has been identified and confirmed to at least the genus level.
Less objection to destructive testing of the Shroud's pollen. This is a practical advantage of carbon-dating the Shroud's pollen compared with its linen. The Shroud itself is regarded by the Roman Catholic church as a holy relic, irrespective of whether it is authentic, so it seems unlikely that the Church would ever agree again to destructive testing of the Shroud's linen. But that the Shroud's pollen has little or no theological significance to the Church is evident that it allowed Max Frei, a private citizen and a Protestant, to collect pollen from the Shroud and keep it in his private collection.
... Moreover, there seems to be abundant pollen grains on the Shroud. There seems to be more than enough pollen, not only in the Frei collection, but also on the Shroud itself, for completely testing every different pollen type. It should therefore be possible, in the longer term, to fully test Wilson's theory, if necessary.
Pollen from different parts of the Shroud can be tested. Initially it is proposed that only one grain of pollen of one type be dated at a time (see part #2), so this is a longer-term advantage. But because the 1988 dating of the Shroud's linen was from only one location, and it seems unlikely that there will be any further destructive tests of the Shroud's linen (see above), future carbon-datings of pollen grains of the same type from different locations of the Shroud will be inherently more representative of the whole, and therefore more scientifically valid, than that single-location dating of the Shroud's linen. Therefore, if there is a significant difference between the carbon-dates of the Shroud's linen and its pollen, the latter should prevail over the former.
Continued in part #2.