In the Duomo in Turin, hidden from public view, rests a sheet of cloth bearing the faint image of a man. Many claim that this is the actual burial shroud of Jesus of Nazareth, and physical evidence of his Resurrection. Several lines of investigation have been carried out into the Shroud. Many of these were performed by STURP¹ in 1978, in the only extensive set of tests ever permitted on the Shroud. A more detailed description of the Shroud is available elsewhere; this Entry will look at the evidence that has been presented by those on both sides of the debate over its authenticity.

Blood Stains

There are blood stains on the Shroud, some of which seem to be pre-mortem and others post-mortem. There is also a claim that they were placed on the Shroud before the image was formed. Both of these claims would be consistent with the Shroud being used to wrap a recently deceased body.

The blood has been identified as Type AB (though there is a counter-claim that this blood type did not become common until c700 AD). Alan Adler and John Heller concluded that the flecks of red on the STURP tapes were real blood, based on a range of forensic tests including UV fluorescence spectroscopy, which discovered the presence of invisible traces of bilirubin (one of the compounds blood serum decays into). At least two separate analyses have concluded that the red stains are not blood, including one performed by the microscopist and forgery expert Walter McCrone (also a STURP member), who claimed that egg white used in paint was giving false positives in blood-detection tests looking for protein.

Likewise, at least two analyses have concluded that it is real blood. Iron oxide has been detected, but there is dispute about whether this is the remains of haemoglobin (indicating real blood) or a pigment (indicating an artistic forgery). So we are left with vocal claims from both sides about the presence or absence of human blood, and the presence or absence of vermilion paint, with each side able to point to qualified experts and seemingly-reliable tests to support their case.

Microscopic Analysis

The Shroud is centuries old, widely travelled and very well-handled. Microscopic and chemical analysis are hampered by the fact that the Shroud contains all sorts of dirt and impurities, from dust and skin to stray fibres from gloves and clothing. Whatever the Shroud is, it seems clear that it is not a painting. There is no layer of pigment coating the fibres, contrary to what would be expected if the image were formed of paint that had been added to the Shroud. Instead, it is a discolouration of the surface of each individual fibre — indeed, of one side only of the surface of each fibre.

McCrone, fresh from denying that there was blood on the Shroud, has claimed that instead he has found tiny crystals of vermilion paint. While it seems to be widely accepted that these exist, there is disagreement over whether they are found exclusively in the 'blood' areas of the Shroud (as McCrone explicitly claimed) or over the whole Shroud in quantities too small to be visible. This second option would be explained if they are impurities caused by centuries of handling of the cloth.

3-D Structure

One of the most unusual claims about the Shroud is that it contains '3-D encoding'. When STURP ran the image on the Shroud through a computer called a VP-8, originally designed for producing 3-D images of planets from photos taken by NASA probes, they produced a 3-D image that has been described as 'encoded' in the 2-D shroud. Even photographs of people do not come out as clearly, instead being distorted and skewed. However, this is more impressive than it sounds. All the VP-8 essentially does is assume that brighter areas are closer to the viewer than darker areas. Photos are skewed because of uneven lighting on the two sides of the face; this is not a problem for the Shroud. Furthermore, a number of 'corrections' needed to be made to the 3-D image to improve its recognisability.

Dr Petrus Soons has used this 3-D data to produce a hologram of the Shroud, which he claims shows the actual face of the historic Jesus.

Historical Documents

Gyorgy Pray, a Hungarian Jesuit, was researching documents relating to the early written Hungarian language when he came across an illuminated manuscript from 1192-5. Now named after him, this 'Pray Codex' was an item of minor academic interest for many years as the earliest example of Hungarian text. But it also contains an image of Jesus rising from the grave, in which particular attention seems to have been paid to the grave-clothes. Although no image is shown on them, they have a curious zig-zag pattern, which may represent the weave of the Turin Shroud. More significantly, there are four small circles, arranged in an L-shape. These match closely a pattern of burns in the Turin Shroud (not to be confused with the large burns caused by the Chambéry fire), giving good evidence that the Shroud was in existence at least 150 years before Shroud skeptics have it being created.

Those skeptics do not have a direct response to this; instead, they would point out that it seems bizarre that an artist would pay such close attention to the weave of the cloth (and include a cross motif clearly not present on the Shroud) and then not include the image itself. Instead, they would insist that the pattern of holes is mere coincidence.

As noted above, religious forgeries were common through the Middle Ages, and the first undisputed reference to the Turin Shroud declares it to be a forgery — specifically a painting (although this cannot be literally true — see the 'Microscopic Analysis' section above). As such, it is not unreasonable to approach the subject with the idea that the Shroud is a fake.

The image on the Shroud has striking similarities with Christian icons. To Shroud skeptics, this indicates that the Shroud, like the paintings, is a creation of Christian hands. Of course, to sindonologists², it merely indicates that the artists were basing their images on the Shroud, directly or indirectly.

Pollen

Samples taken on tapes from the Shroud have been shown to contain pollen. It has been claimed that by analysis of the species of plant, the location and date of the Shroud can be narrowed down to the region of Jerusalem in the spring (around the time of the Passover, when Jesus was crucified). However, these samples were provided by Dr Max Frei in 1972. Frei has since been shown to have a history of forgery, and the relevant species are found on only one of the dozens of samples he took, leading to a strong suspicion of deliberate forgery. Despite claims to the contrary, it has not been possible to identify plant outlines on the cloth with any certainty.

Absence of Signs of Painting

Another unusual claim is that the image on the Shroud is 'directionless'  — there are no signs of brushstrokes. Together with the absence of obvious pigment, this would seem to rule out the idea that the Shroud is a painting — although other options (such as a rubbing or acid imprint on the cloth) exist.

Weave of the Cloth

The weave of the cloth  — 'herringbone' — has been presented as evidence of authenticity, since it is known from 1st Century Palestine. However, this is hardly conclusive, as it is also known from 14th Century Europe, and a wide variety of other places and locations. Indeed, Shroud skeptics dispute whether such cloths are known from 1st Century Palestine, and claim that Jewish burial customs of the time required several strips of cloth wound around the body, not a single sheet draped over it.

More recently, the discovery of a 1st Century Jerusalem burial shroud has been held up as further evidence against the authenticity of the Turin Shroud. Despite being the burial shroud of a wealthy man, it is of a simpler weave than the Turin Shroud, which implies that cloths like the Turin Shroud were not used at the time.

Anatomy — of a Forgery?

Several of the anatomical details on the Shroud seem unlikely to be the work of a forger. The crucifixion nails pass through the wrists, which would have been able to bear the weight of a human body, rather than the hands, as was usual in medieval iconography. The image has no thumbs, probably due to contraction of the muscles caused by the wounds to the wrists. This speaks of a detailed knowledge of human anatomy that would not have been widely available in the Middle Ages (although some groups practice self-crucifixion to this day) — or of the use of a genuinely crucified body.

Other anatomical details have raised concerns. The head appears 'detached' according to some. And the body the Shroud was draped over seems to have been curiously flat — if the cloth had been draped over a real human body it would have touched the sides of the head, for instance, and so the image would be distorted. The eyes appear towards the top of the head (as they are often placed by unskilled artists), not in the centre (as in real life). The colour of the blood is a bright red, not the dull brown of ancient blood, and the blood flows in neat rivulets with no sign of matting in the hair. This is very unlike how human blood flows.

The posture is unnatural, and seems to owe more to human prudishness than nature, with the wrists crossed over the groin. However, there are known examples of this burial posture from the period. The fingers are strikingly long — indeed, longer on one hand than the other, and the same is true of the forearms. Also, the man is unusually (but not impossibly) tall for the period. It has been claimed that the image of his back is taller than the image of his front. Perhaps most striking of all is the fact that the hair hangs down towards the shoulders, as though the man is standing; a corpse would, of course, have been reclining and the hair would naturally have fallen back away from the face.

Carbon Dating

In 1988, a bombshell hit Shroud believers.

Carbon-14 dating was performed on the Shroud. The results were unambiguous. Three separate laboratories dated fragments of the Shroud, in blind tests alongside a piece of cloth known to be medieval (specifically, from Louis IX of France's cloak³) and other pieces from Egyptian burials (one previously dated to 1100 AD and another previously dated to around 200 AD). Oxford University, the University of Arizona and the Swiss Federal Institute of Technology in Zurich all determined the Shroud to be from 1260 - 1390; right around the age Shroud skeptics had always claimed, with the Shroud being forged in the early 1300s. For many people, that settled the debate. For diehard Shroudies, however, this result was not acceptable and the challenge immediately became to find a reason that the testing was wrong.

First came allegations of a conspiracy to discredit the Shroud.

Next came the suggestion that the sample of Shroud analysed had been from a portion repaired during the Middle Ages. If this were true, the carbon dating would be measuring the date of the repair, not the age of the cloth itself. Unfortunately, the original testing samples were carefully chosen to be away from areas of repair, so this idea seems weightless.

There followed some more 'interesting' ideas. Perhaps bacteria had formed a film (a 'bioplastic coating') around the fibres of the Shroud — the dating would then give a date somewhere between the true date of the Shroud and the average age of the bacteria. Again, there were a few small problems. Firstly, such a thing had never been observed in any other 1st Century cloths. Then, as McCrone put it: 'A weight of 20th Century carbon equaling nearly two times the weight of the Shroud carbon itself would be required to change a 1st Century date to the 14th Century'.

Attacks on the protocol are more realistic but less serious to the reliability of the dating. It is true that the Church made several alterations to the testing protocols, including that only one sample would be taken rather than several, it would be taken from the edge of the cloth not the middle, and would be sent to fewer institutions than STURP originally wanted (in fact, STURP was removed from the radiocarbon dating tests after another acrimonious falling out). More seriously, the variation in the dates was initially reported to be within the bounds of experimental error, but this has since been shown to be incorrect; the dates vary by more than would be expected from chance alone⁴.

Finally, the debate has come full circle. Shortly before his death, Ray Rogers, formerly of STURP, claimed that the section of Shroud dated runs across a seam where a repair was patched into the original fabric. Since the seam runs diagonally, this would explain the variation among the dating results. He said that the seam was not detected during the STURP tests because it uses a very sophisticated (but historically known) form of invisible mending. He based this on the presence of cotton in the tested section (the Shroud is made of linen, not cotton) and chemical differences from the rest of the Shroud. Shroud skeptics, perhaps unsurprisingly, deny this, pointing out that the 'different chemical' (specifically lignin) Rogers claimed is found only on the tested sample were also reported on image samples taken by McCrone, and that cotton is likewise found throughout the Shroud.

Rogers proposed an alternative dating method based on the chemical decay of lignin to vanillin and giving results of 1,300 to 3,000 years old. Unfortunately, this is a chemical process and, unlike radioactive decay, varies strongly with temperature and pressure. It has never been successfully used to date an object of known age.

Wilder Claims

When dealing with an artefact said to be intimately connected to the most famous human in history, one might as well produce a huge sign saying 'oddballs welcome here'. More than a few individuals who might charitably be described as 'bug-eyed loons' have contributed to the Shroud debate. So let us take a few minutes to laugh at some of the wilder edges of this already-fringe field.

Dmitri Kouznetsov, a Russian Creationist, announced in 1994 that water and heated silver (such as would have been present in the Cambéry fire) could catalyse increased C-14 levels by using carbon monoxide from the atmosphere. He was exposed as a fraud by Professor Gian Marco Rinaldi and was later arrested for taking bribes. Attempts to reproduce his proposed reaction under laboratory conditions have so far failed.

Various researchers have claimed that a highly detailed microscopic analysis of the Shroud has revealed the impressions of coins over the eyes. These coins have been identified as coming from the 1st Century Roman Empire. As with the claims of recognisable impressions of flowers (which only narrowly escaped being categorised under this heading themselves), the trouble is that these images seem to owe more to the imagination of the microscopist than to objective reality — some claim they are Roman coins, others that they have Greek text. Furthermore, there was no tradition of placing coins on the eyes of corpses in Jewish burials at the time⁵.

The carbon dating has attracted its fair share of crank claims as well. Allegations of switching of samples are unsullied by the presence of brute facts, and the assertion that there was a 'double peak' in the results (showing a 1st Century cloth with much later patches) show a basic misunderstanding of how carbon dating works — even if there were two separate ages of cloth, carbon dating would give a single average date, not a 'double peak'. Naturally, for some, a vast atheist conspiracy (including several senior Catholic priests and possibly STURP as well) to debunk the Shroud is the best explanation.

More recently, a Vatican researcher has claimed to find text on the Shroud containing what amounts to a death certificate. This has been decried by other experts as 'the result of imagination and computer software'.

Other claims that might have even the Annals of Improbable Research blushing are related to the exaggeration of the clarity of the negative image, stating that there is a mysterious physics going in involving the interaction of light and the Shroud (there isn't — the effect is a combination of the human brain recognising faces more easily when the prominent areas are light and photographic enhancement of well-known copies of the negative photo).

The Verdict...

As the reader may have noticed, there are few claims about the Shroud that are undisputed, even when these relate to simple statements of fact such as the presence or absence of vermilion on non-'blood' areas of the Shroud. As such, this Entry will not attempt to reach a definitive conclusion as to the truth behind the Shroud — readers can make their own judgements.

For many, the radiometric dates remain convincing, especially when combined with the known history of forged relics. For others, the nails through the wrists and the Pray manuscript may be enough to convince them that there are problems with the carbon dating. Perhaps this question could be resolved by more extensive testing... or perhaps we will never now know for certain the truth behind this remarkable artefact.