DNA analysis claiming new origins for the Shroud of Turin doesn't hold up, experts say

A metagenomic study of this cloth, controversially purported to bear the imprint of the body of Jesus Christ, has little to say about the relic’s origins

By Stephanie Pappas edited by Jeanna Bryner

The Shroud of Turin, claimed by some to have wrapped the body of Jesus after his crucifixion, got a publicity boost during Easter week with the release of new research that suggests that the relic may have been made with yarn from India and spent time traversing the Mediterranean region after it was woven.

If accurate, those findings might hint that the shroud is indeed from the Levant, an area considered to have been the cradle of Christianity and the setting of both the Old and New Testaments of the Bible. But the study, which has not yet been peer-reviewed, has some methodological weaknesses that limit interpretation of the research, outside experts say.

“There is a lot of legwork that needs to be done to actually convince me of any of these results,” says Allison Mann, a biological anthropologist at the University of Wyoming, who was not involved in the study.

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The researchers, who posted their work to the preprint website bioRxiv, used preliminary methods to match genetic sequences found on the cloth to species of plants and animals. But those methods are prone to false positives, Mann says.

The shroud is already extremely controversial. Housed in the Cathedral of St. John the Baptist in the eponymous city of Turin, Italy, the cloth holds a sepia-toned negative image that resembles the front and back of a bearded man with his eyes closed and his arms crossed.

It first appears in the historical record in the 1350s, when a Catholic Church official displayed it in a church in Lirey, France, describing it as the shroud that wrapped Jesus's body, says Andrea Nicolotti, a historian at the University of Turin and author of The Shroud of Turin: The History and Legends of the World’s Most Famous Relic (Baylor University Press, 2020). The relic was accused of being a fraud almost immediately: Between 1355 and 1382, a Norman scholar wrote a treatise that described the shroud as a “patent” example of a fake. And around 1389, the bishop of that region of France reported in a letter to the pope that an artist had confessed to making it.

Things have not calmed down since then. For a 1989 study published in the journal Nature, three independent labs radiocarbon-dated a small piece of the shroud and found, with 95 percent certainty, that it was made between 1260 and 1390, not during the lifetime of Jesus 2,000 years ago (point: Norman scholar). Believers in the shroud dismiss these findings.

Now the new study, conducted by genomics researchers Gianni Barcaccia of the University of Padua and Alessandro Achilli at the University of Pavia, both in Italy, and their colleagues, pulls together all the genetic sequences found on a fragment of the Shroud of Turin that was clipped by scientists in 1978. The pair sequenced all the genetic fragments in the mix—an approach called metagenomics—and then matched them to those of known human ancestry groups, plants, animals and microbes. The result was a cornucopia of genetic contamination, including human DNA matching the original collector of the 1978 sample, as well as human DNA that is common in western Eurasia, Europe and the Near East. Also present was DNA from cats, dogs, cattle, pigs, carrots, wheat, corn, peanuts and bananas. A 2015 analysis by the same research group of dust particles vacuumed from the back side of the shroud showed a human genotype originating from the India subcontinent.

“Overall, the reappraisal of the outcomes from the analysis of the DNA traces found on the Turin Shroud suggests the potentially extensive exposure of the cloth in the Mediterranean region and the possibility that the yarn was produced in India,” Barcaccia wrote in a statement to Scientific American. (The authors declined an interview because the paper has not been peer-reviewed.)

That interpretation isn’t the only possibility, however, just as the presence of banana DNA doesn’t prove the Shroud spent time in Malaysia or the_ Philippines. The shroud has been transported and displayed in France, Switzerland, Belgium and Italy, Nicolotti says, and it has been in contact with countless hands and exposed to open dust- and bacteria-filled air countless times. “Since the object has been touched by people coming even from distant places, as well as by objects likewise originating from faraway places, it was contaminated in various ways, without any possibility of reconstructing all the stages and the point of origin,” he says. Taking perhaps more wind out of these biblical sails, he adds that there were no looms capable of creating a large cloth in the weaving style of the shroud in the Mediterranean Basin before the Middle Ages. A cloth like the shroud would have been made with a horizontal treadle loom with four shafts, he says. Treadle looms are thought to have originated in China around C.E. 1000, whereas the four-shaft version was introduced by the Flemish around the 13th century, according to Nicolotti.

In addition, it’s not clear that all the contamination findings are accurately matched with a species. The human and microbial findings are likely trustworthy, says Christina Warinner, an anthropologist at Harvard University, who studies ancient microbiomes. But the plant and animal results came from an alternative method of DNA matching that is known to handle animals and plants poorly.

“The coral, animal and plant IDs will all need to be very closely scrutinized and verified,” says Warinner, who was not involved in the study, “and I suspect most are data artifacts.”

If the authors submit the paper to a journal, reviewers will probably ask for validation steps before accepting it for publication, Mann says. There are also further genomic techniques that the researchers could use to determine whether the DNA on the shroud is ancient or whether these contaminants are recent, she adds. Metagenomics can’t prove the shroud is older than the Middle Ages, however. Such a determination would require new radiocarbon dating that overturns the original results, which would involve clipping and destroying another snippet of shroud—a step that the Vatican is unlikely to allow.