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MEDIEVAL DNA SLEUTHING
A TWELFTH-CENTURY Gospel of Luke and an even older York Gospels are giving today’s bookworm biologists an opportunity to study the actions of actual 900-year-old book worms in these medieval texts. Modern techniques are revealing details of the books’ parchment construction and, even more astonishing, the microbial DNA of those using these medieval books for swearing oaths of allegiance.
The July 28, 2017, issue of Science, published by the American Association for the Advancement of Science, has an article “Biology of the Book,” by Ann Gibbons, with a summary available online. Here are tidbits gleaned from Science magazine.
Typically, surviving old manuscripts are treasured today. Indeed, there’s controversy among humanities scholars whether gloves should be worn when examining them. Some feel bare hands give a more delicate touch. Biology scholars opt for surgical gloves to minimize modern DNA contamination.
This and a following image from Science, July 28, 2017.
Crucial to these analyses is a nondestructive means of extracting ancient proteins from the books. Science writer Ann Gibbons describes the technique: “Librarians often ‘dry clean’ a rare manuscript by rubbing it lightly with a polyvinyl chloride eraser, which pulls tiny fibers off the page in curled debris that’s usually swept away.” It’s this debris that is now collected, classified, and analyzed through mass spectrometry.
The Gospel of Saint Luke, in Latin, manuscript on vellum, as described by Sotheby’s, July 7, 2009. Estimated at £60,000 to £80,000, the manuscript sold for £253,250.
The Gospel of Luke was produced by scribes at St. Augustine’s Abbey in Canterbury, England, around 1120 A.D. For the past five years, researchers have been studying what one called the book’s “rich palimpsest of molecular data.” (A palimpsest is a piece of writing material, parchment, for example, given further use by scraping off its previous writing.)
Gibbons notes, “Researchers can even isolate the microbes spewed on manuscripts when people kissed, coughed, or sneezed on them.” Another medieval book from around 990 A.D., the York Gospels was used by English clergymen in swearing oaths of allegiance 700 years ago (and is still employed in ceremonies today).
The York Gospels, Image from newscientist.com. For more details, see “The York Gospels: A One Thousand Year Biological Palimpsest, Teasdale et al, 2017.
“For example,” Gibbons writes, “researchers identified DNA from bacteria known to live in human skin and noses, including an abundance of two genera—Propionibacterium, which causes acne, and Staphylococcus, which includes strains that cause staph.” Almost 20 percent of the York Gospels DNA samples were of humans or microbes shed by humans.
The challenge is identifying the age of the bacteria. “For example, an image of Christ on the cross in the Missal of the Haarlem Linen Weavers Guild, circa 1400 A..D., was apparently kissed repeatedly by a Dutch priest…. Eraser shaving DNA might reveal that priest’s hair and eye color, ailments, and ancestry.”
The Gospel of Luke is considered in wonderful condition for a 900-year-old manuscript. It has leather-bound covers of oak and 152 leaves of vellum, with flyleaves at each end. These are arrayed in 19 quires, each of four skins folded together.
Researchers treated the parchment as biological samples that told a tale about the book’s fabrication and its era. Quires I through IX are interleaved patterns of calfskin and sheepskin. At the end of quire X, a new scribe writing commentary accompanied a change to 100-percent calfskin for quire XI and different interleaving for quires XII and XIII.
Then, curiously, quire XIV replaces sheepskin with goatskin, a parchment of less quality perhaps used as a last resort. A new main scribe arrived with quire XV and with him came another change in parchment: The final quires, XVI through XIX, are all sheepskin.
The leather binding and strap had historical interest too: The book’s cover is of roe deer; however, notes Gibbons, “… the strap is made from another larger species, either a native red deer or fallow deer introduced from continental Europe, possibly by the Normans after their invasion in 1066.”
Old books have been attacked by book worms, and these creatures left their identifying marks as well. The beetle larvae start their tunneling through wood covers and grow as they eat their way through. By comparing sizes of entrance and exit, researchers are able to identify the beetle species.
DNA researchers are coming to the aid of modern bookworms: One scholar noted the challenges of studying handwriting and dialect of a medieval document. “Now,” Gibbons writes, “he says, ‘I could go ask a biologist.’ ” ds
© Dennis Simanaitis, SimanaitisSays.com, 2017
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