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Jim Forest, Flickr Creative Commons // CC BY-NC-ND 2.0
Jim Forest, Flickr Creative Commons // CC BY-NC-ND 2.0

Scientists Devise Clever Way to Test Old Manuscripts’ DNA

Jim Forest, Flickr Creative Commons // CC BY-NC-ND 2.0
Jim Forest, Flickr Creative Commons // CC BY-NC-ND 2.0

When encountering an obstacle, some people stop and give up, some force their way through, and others find another way around. That's what scientists in the United Kingdom have done with a delicate manuscript from the Dark Ages. Barred from taking parchment samples, the resourceful researchers instead analyzed the eraser crumbs left behind after archivists cleaned the paper. They describe their findings in an article on the prepress server bioRxiv.

Co-author and archaeologist Matthew Collins of the University of York did not start out a manuscript man. Collins had been trying to extract DNA from animal bones unearthed at a Viking settlement to learn more about the culture's use of livestock. But the bones had decayed too far to offer much in the way of genetic material. "You can imagine the frustration," Collins said in an interview with The Atlantic.

Then he realized that animal remains can be more than just bones. There are skins, too—and those, at least, we've taken some pains to preserve. At least the ones we've written on.

"You look at [archive] shelves," Collins said, "and every one of them has a skin of an animal with a date written on it."

Collins's excitement at discovering this untapped bounty of data was soon tempered when he and his collaborator, biochemist Sarah Fiddyment, learned that sampling the manuscripts was completely off-limits.

But they weren't about to give up that easily. Fiddyment spent weeks following the conservators as they worked with the fragile animal-skin paper, learning their process and watching for possible openings. Finally, she saw it: eraser crumbs.

Conservators routinely use PVC erasers to lift stains, grime, and damage from historic documents. The friction created by gently rubbing the eraser against the paper creates an electric charge that pulls in molecules of dirt and oil. And probably other things, too, Fiddyment thought.

Fiddyment, Collins, and their colleagues began collecting eraser crumbs from manuscript conservators around the world. They analyzed each document's chemical makeup and were even able to compare proteins to identify the livestock species responsible for the skin.

The next step was to look at the DNA itself. The researchers turned to the York Gospels, a leatherbound Bible with pages dating back to the year 990. By collecting another tiny pile of eraser crumbs from cleanup of eight pages, they were able to collect enough of a sample to run thorough DNA tests.

Those pages had quite a lot to say about their creation and history. The tests revealed 1000-year-old genetic material from the cows and sheep that gave the book its parchment pages. Remarkably, the DNA was so intact that the scientists could identify the cows' ancestry (something close to our modern-day Norwegian reds and Holsteins) and sex (mostly female).

The pages also contained human DNA and even bacteria, most likely from the hands and saliva of the people who made, wrote, and used the book.

Speaking to The Atlantic, parchment expert Bruce Holsinger of the University of Virginia called the findings "an exciting breakthrough."

[h/t The Atlantic]

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History
The Queen of Code: Remembering Grace Hopper
By Lynn Gilbert, CC BY-SA 4.0, Wikimedia Commons

Grace Hopper was a computing pioneer. She coined the term "computer bug" after finding a moth stuck inside Harvard's Mark II computer in 1947 (which in turn led to the term "debug," meaning solving problems in computer code). She did the foundational work that led to the COBOL programming language, used in mission-critical computing systems for decades (including today). She worked in World War II using very early computers to help end the war. When she retired from the U.S. Navy at age 79, she was the oldest active-duty commissioned officer in the service. Hopper, who was born on this day in 1906, is a hero of computing and a brilliant role model, but not many people know her story.

In this short documentary from FiveThirtyEight, directed by Gillian Jacobs, we learned about Grace Hopper from several biographers, archival photographs, and footage of her speaking in her later years. If you've never heard of Grace Hopper, or you're even vaguely interested in the history of computing or women in computing, this is a must-watch:

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science
Why Are Glaciers Blue?
iStock
iStock

The bright azure blue sported by many glaciers is one of nature's most stunning hues. But how does it happen, when the snow we see is usually white? As Joe Hanson of It's Okay to Be Smart explains in the video below, the snow and ice we see mostly looks white, cloudy, or clear because all of the visible light striking its surface is reflected back to us. But glaciers have a totally different structure—their many layers of tightly compressed snow means light has to travel much further, and is scattered many times throughout the depths. As the light bounces around, the light at the red and yellow end of the spectrum gets absorbed thanks to the vibrations of the water molecules inside the ice, leaving only blue and green light behind. For the details of exactly why that happens, check out Hanson's trip to Alaska's beautiful (and endangered) Mendenhall Glacier below.

[h/t The Kid Should See This]

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