XVI International Botanical Congress: The Shroud of Turin Controversy Returns

Courtesy of Alan Whanger Facial image of the Man of the Shroud surrounded by "the ghost of flowers past." The topic of the last press conference on Monday, August 2, at the XVI International Botanical Congress in St. Louis seemed to have a nice mix of classical scientific observation, image analysis, and palynology (pollen identification), as well as great historical interest. A team led by Avinoam Danin, a professor of evolution, systematics, and ecology at the Hebrew University of Jerusalem, had tentatively identified the ghosts of flowers past on the famed shroud of Turin.1 The work resurrected the idea that the shroud held the body of Christ, countering radiocarbon dating evidence that it is of medieval origin.2 This new look at an old story was sexy stuff, and by Tuesday morning the press room at the conference was festooned with qualified but largely uncritical clips from the likes of the Associated Press, USA Today, and The New York Times. Interest snowballed. As the week progressed, Danin found himself juggling phone interviews from all over the world and entertaining a steady stream of television journalists. Many tried repeatedly to pin Danin down to admitting that his work had authenticated the shroud, but he answered simply, "I am a Jewish botanist, not a theologian. I identify images of flowers and tell their geographic origin, not that this is Jesus or not." The botanical congress offered so many symposia that a public relations firm was hired to funnel what it perceived to be newsworthy research to the media. Standard procedure. They goofed by hyping work on an African bean extract with in vitro activity against Ebola virus. Seasoned journalists at the news briefing recalled reporting the work earlier, and finally got the speakers to admit that the substance faced the same 1:10,000 odds of making it to the drugstore as any other natural product. A session on algal blooms was also familiar turf that oversimplified to the point of using the long-defunct term "blue-green algae" and committing the taxonomic faux pas of calling them plants. The shroud of Turin story, though, had appeal because it transcends health and science. A closer look at the new botanical evidence, and the radiocarbon dating that it questions, reveals the clash between media seeking an immediate, conclusive answer, and the slower, much more skeptical pace of science. Christ was buried, according to Jewish custom, before 6 p.m. on a Friday, three hours after he died. His body was wrapped in a shroud and placed in a cave guarded by large rocks. Three days later the body had disappeared, and the cloth somehow came to bear the life-size, full-body image of the man. In 30 A.D., a disciple of Jesus brought a cloth, presumably the shroud, to the king of Edessa (part of Turkey), where it supposedly cured him of leprosy. Word spread, and other cities developed icons of the facial part of the image. The shroud survived a great flood in Edessa in 525 A.D., then was taken to Constantinople in 944. Crusaders grabbed the shroud in 1204, and its whereabouts remained unknown until 1357, when it went on public display in Lirey, France. A royal family in what is now Italy acquired the shroud in 1453, and it began display in Turin in 1578, with a brief removal in 1997 due to fire. The photographic history of the shroud of Turin begins in 1898. That first photograph looked like a positive, and when it was photographed, the image of the crucified man that emerged was startling. In 1977 an enhancement of a 1931 photograph attracted the attention of Alan Whanger, professor emeritus at Duke University Medical Center, who is a psychiatrist and a surgeon. Two years later a colleague of Whanger's visiting a sixth-century church in the Sinai desert was given a small, gold, Byzantine coin. "The [coin icon] was painted, the monks told him, from the shroud of Turin, and it had flowers," says Whanger. Reasoning that the shroud could not have been faked in the Middle Ages if an icon reportedly from the sixth century resembled it, Whanger and his wife, Mary, who works at the Council for Study of the Shroud of Turin in Durham, N.C., developed an optical technique to compare the coin and the image on the shroud point by point.3 The approach, called polarized image overlay, projects images through polarizing filters at orthogonal angles revealing darkened "points of congruence" that align the two objects. The coin and the image on the shroud matched at 211 points--a much closer correspondence than forensics use to match photographs of faces or fingerprints, Whanger says. But it is a chicken-and-egg argument. Couldn't a medieval artist have copied the coin icon onto the shroud? In 1983 another optical technique hinted that there was more to the shroud than met the eye. German physicist Oswald Scheuerman thought that he saw the faint outlines of flowers on a photo of the shroud. He used a technique called coronal imaging to track the flow of electrical energy from a Van der Graaf generator over pieces of plants held in front of linen, demonstrating that images of flowers and thorns can indeed be generated on cloth. Excited that his optical points of congruence might be the flowers that Scheuerman saw, Whanger became what he calls a "late-bloomer botanist," poring over botany books, then traveling to Israel to photograph flowers. He worked for four years, tentatively identifying flora and attempting to publish his findings in 1989. But Whanger's timing was off--the radiocarbon dating paper had just appeared. "The fact that everyone thought the shroud was a fake, and that I wasn't a botanist, combined to make the work ignored." What Whanger needed was a botanist, and in 1995 he found Danin, an authority on Middle Eastern flora. "He's a good scientist; he'll look at anything once. And in 20 seconds he said, 'Those flowers are from Jerusalem,'" Whanger recalls. Danin identified three types of plants--chrysanthemum flowers, thorns of Gundelia tournefortii, and leaves of Zygophyllum dumosum--whose modern geographic ranges overlap between Jerusalem and Hebron. Chrysanthemum is widely distributed, but Zygophyllum has a much narrower range, with a very distinctive double leaf that falls off at summer's end. Gundelia is a thistle that belongs to the sunflower family, blooms between March and May, and is insect-pollinated, indicating local origin, Danin says. Supplementing Danin's flower identifications is a reanalysis of pollen on the shroud by Uri Baruch from the Israel Antiquities Authority. The pollen samples were first collected in 1973 and in 1978 by Max Frei, founder and director of the scientific department of the Zurich Criminal Police. Frei obtained pollen with sticky tape, but was familiar only with European plants, so that by the time he died in 1983, the identifications were incomplete. Although Danin admits that pollen analysis cannot date an antiquity, the 313 pollen grains that Baruch scrutinized are consistent with the species that Danin identified from floral morphology. The group's conclusion: The shroud hails from the region of geographic overlap. But couldn't people have carried plants from one place to another? The suggested time frame is questionable too. To support the sixth-century ballpark figure derived from the coin icon, the researchers point to a facial cloth, called the Sudarium of Oviedo, that was supposedly placed directly over the face, beneath the shroud. The Persians took this cloth through North Africa to Spain in the eighth century. It bears dark stains in a pattern similar to the facial likeness on the shroud, as well as pollen from the same type of thistle. The nature of these stains has been the focus of intense debate, with identifications ranging from type AB human blood to paint. Accepting the blood verdict, Danin and Whanger conclude that the shroud must predate the eighth century, which is the earliest time that the facial cloth's location is known. "This pollen association, congruence of blood patterning, and probable identical blood type suggests that the radiocarbon dating of the shroud to only the Middle Ages is untenable," they conclude in their paper. But again, the facial cloth pattern could have inspired the later image on a medieval shroud. Danin and colleagues and others challenge the accuracy of the radiocarbon dating. "Three labs used the same sample from the dirtiest edge of the shroud that had been water-stained and scorched. This would produce a younger date," says Danin. The shroud may also bear biological contamination, some say. In 1993 two University of Texas at Austin microbiologists, Stephen Mattingly and Leoncio Garza-Valdes, described a "bioplastic layer" of modern bacteria and fungi within the linen fibers of the shroud, which could have thrown off the carbon-14 date.4 But the radiocarbon dating paper is impressive. A 10 x 70-mm piece from the shroud was cut from a region free of char, snipped in three and given to dating labs at the University of Arizona in Tucson, Oxford University, and the Institute fur Mittelenergiephysik in Zurich. Collaborators hailed from Columbia University and the British Museum. Controls were three samples of linen with known dates. "The region was chosen very carefully by textile experts to contain no material but shroud. The shroud is a woven piece, and one region of it is as representative of the whole as any other," explains Douglas Donahue, a professor of physics at the University of Arizona who was present at the April 21, 1988 sampling. Each lab subdivided the samples to test them repeatedly, and treated different pieces with different mechanical and chemical cleaning methods. Then each sample was examined microscopically to detect and remove contaminants. The results date the shroud to 1260-1390 A.D., with 95 percent confidence. This corresponds to the period when the shroud's location was unknown, and is consistent with a 14th-century bishop's report that a forger had confessed. Donahue defends the radiocarbon dating. Neither water nor burn marks would alter the date, he says, nor has Mattingly and Leoncio Garza-Valdes' "bioplastic theory" been published in a peer-reviewed journal. "The bacterial material they propose is invisible to normal human beings, including myself, is impervious to reasonable chemical treatments, and is made of only modern carbon. In order to change the radiocarbon age of the shroud from the 700 years, which we measured to 2,000 years, the shroud would need to consist of 60 percent of this bacterial substance." By Thursday of the week of the botanical congress, the story of possible new scientific evidence for the authenticity of the shroud of Turin had made its way around the globe. Then on Friday, August 6, the Amherst, N.Y.-based Committee for the Scientific Investigation of Claims of the Paranormal (CSICOP), an international network of scientists who examine pseudoscience, added its two cents. Their report, compiled by CSICOP senior research fellow Joe Nickell, claims that Frei's pollen-rich tapes could not be replicated, and that all but one tape reexamined after Frei's death had little pollen--and that this was an old story. Nickell mentions other images seen "Rorschach-like" in the shroud, attributes the "blood" stains to tempera paint, and calls linking the shroud to the Sudarium of Oviedo by the pattern of marks and pollen "wishful thinking." Danin and Whanger expected some skepticism, and they were careful to limit any mention of dates to "as long ago as the eighth century." Still, others interpreted their work to mean that flowers adorned the body when it was prepared for burial, with some reporters likening an uneasy Danin to a messenger from the almighty. But for many people, evidence supporting the shroud as the burial garment of Jesus Christ is moot. Those who believe that the image formed as Christ rose will hardly be swayed otherwise by radiocarbon dating, and will continue to see in the faint flowers on the shroud what they want to see. But from a scientific standpoint, about the only near certainty regarding the new view of the shroud of Turin is that it is likely to turn up as an episode of The X-Files. Ricki Lewis (rickilewis@nasw.org) is a contributing editor for The Scientist. A. Danin et al., Flora of the Shroud of Turin, Missouri Botanical Garden Press, 1999. P.E. Damno et al., "Radiocarbon dating of the shroud of Turin," Nature, 337:611-5, 1989. A.D. Whanger and M.W. Whanger, "Polarized image overlay technique: a new image comparison method and its applications," Applied Optics, 24:766-72, 1985. L. Garza-Valdes et al., "A problematic source of organic contaminant of linen," Nuclear Instruments and Methods in Physics Research, Section B:504-7, Amsterdam, ier, 1997.

XVI International Botanical Congress: The Shroud of Turin Controversy Returns

Sep 12, 1999

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