Science helps decipher texts in ancient scrolls
A group of scientists have revealed, for the first time, the writing at the interior of a papyrus scroll that has remained unread for nearly 2,000 years, lending a hand to archeology and our understanding of Greek literature and philosophy (more detail on this at the end). Having looked at the state the rolled parchment is in (pictured above), it’s amazing what today’s technology can do. The finding, which the scientists call a proof of concept, is published this month in Nature Communications.
One way to scan the interior of the brittle scrolls, without unrolling them, is to use X-ray computed tomography (XCT), a technique with broad application, such as creating cross-sectional images (like virtual slices) of the brain. This method is based on a property of X-rays, which are absorbed differently depending on the materials that the beam passes through. Objects can be distinguished and visualized by measuring the variations in the X-ray absorption. For example, XCT can tell apart the skull from the brain and identify tumors. However, in the scroll’s case, difference in the absorption between the ink and papyrus is minimal and difficult to measure using the conventional method.
To overcome this challenge, the scientists used a refined version of XCT, called X-ray phase-contrast tomography (XPCT). This method can achieve much enhanced contrast between different materials. It measures shifts in X-ray diffractions, or how much the beam is bent when it passes through different objects, in combination with the absorption difference. (This strategy is actually very similar to how scientists visualize proteins and other small biomolecules in a method called X-ray crystallography.) The result allows scientists to discriminate objects of similar composition, such as charcoal ink and charcoal-turned papyrus paper.
In the report, the scientists identify Greek alphabets from the scroll (pictured below, top row). They also discern a specific style of handwriting that is characteristic of the mid-1st century BCE, as seen in a previous study of an unrolled scroll (pictured below, bottom row). From these clues, they suggest the author of the texts could be Philodemus, a Greek philosopher.
Our results show that XPCT is the first non-destructive technique that enables us to read many Greek letters and some words in the interiors of rolled-up Herculaneum papyri without impairing their physical integrity, as the previous unrolling techniques had done. This is extremely important because the fragility of carbonized papyri requires the most careful manipulation. (from the report by Mocello et al., Nature Communications)
The scientists say further refinement and tuning of the technique would be necessary to decipher complete texts and to delve into deeper layers. The lead scientist Vito Mocella is hopeful. “…[The] scrolls should be readable within the next decade,” he says. Mocella works at the Institute for Microelectronics and Microsystems in Naples, Italy.
The report demonstrates that science has wide applications, from medicine to archeology. I find it fascinating how the advancement in technology can be integrated into solving the mysteries of the past and how experts from seemingly remote fields can come together to achieve the same goal. 🙂
Some backstory of the Herculaneum papyri scrolls:
The specimen probed in the report comes from the ruins of a villa in a Roman town of Herculaneum. This archeological site is “…a unique cultural treasure, as it is the only ancient library to survive together with its books,” the scientists say. (For history buffs out there, the villa that housed the library is believed to have once belonged to a wealthy Roman statesman and Julius Caesar’s father-in-law, Lucius Calpurnius Piso Caesoninus.) What is particular about Herculaneum is that the town was blasted by volcanic gas from the Vesuvius volcanic eruption in 79CE, the very same one that destroyed – or preserved, from archeological point of view – the famous Pompeii. The town, together with the villa, was entombed in a thick layer of ash. Nearly 260 years ago, hundreds of papyrus scrolls were found in the villa’s library, and the site is now known as the Villa of the Papyri.
Since the discovery in the 1750’s, archeologists have tried various methods to read the manuscripts. For example, some scrolls were cracked open in fragments to reveal the inner layers. However, these attempts inevitably damage the scrolls. In recent years, scientists were able to decipher texts from parchments that have already been unrolled in previous attempts or inner sheets near the surface using scanning methods, but the techniques proved ineffective for the writing inside those still rolled or found at deeper interior.
Reading the contents of these ancient scrolls has been a long history of challenge for three reasons, according to Mocello and his team. First, the scrolls were carbonized (turned into charcoal) by the broiling volcanic gas. This makes them extremely fragile, threatening to crumble into pieces at even a light touch; unrolling could permanently damage them. Second, the scrolls are distorted due to the extreme heat during the volcanic eruption. The interior of the scrolls is warped, creating whorls of layers and distorting the scribed texts. Papyrus scrolls are often voluminous, some reaching 15 meters (50 feet) in length when unrolled. Picking at warped, inner layers without unrolling the scrolls, as you can imagine, has been a difficult task. Lastly, the ink used was made from soot, and now it is almost invisible against the blackened, carbonized scrolls.