The Great Isaiah Scroll, one of the largest and best-preserved of the seven Dead Sea Scrolls, was likely authored by two writers rather than one, according to new interdisciplinary research that employed computer-based pattern recognition and artificial intelligence techniques to determine writer identification. 

The Dead Sea Scrolls, discovered at the Qumran archaeological site in 1947, are ancient Jewish religious manuscripts written in Hebrew. They are the oldest manuscripts of the Hebrew Bible — the Old Testament portion of the Christian Bible — dated between the fourth century B.C. to the second century A.D., according to the researchers.

The Great Isaiah Scroll is divided into two halves, with each half containing 27 columns and 33 chapters, and most scholars have argued or assumed that the entirety of the scroll was written by one scribe, according to the researchers of the present study, published April 21 in PLOS ONE. 

The study quantified subtle differences in handwriting between both halves of the scroll, graphically plotting the results on sophisticated scatter plots. The columns from the first and second halves of the manuscript ended up in two distinct zones of the scatter plot, indicating that two writers may have authored the scroll. Statistical analyses of this data further confirmed these findings. 

Researchers also found that the second writer had more variation within their handwriting than the first writer. The overall similarity in handwriting between the two writers, though, may indicate a common training among them and that they were trying to keep the same style of writing, "yet revealing themselves, their individuality" through their handwriting, according to the researchers.

"I find this research exciting because it gives us direct access to the culture behind the Bible, and how that text or those texts were written," Mladen Popović, a co-author of the paper and professor at the University of Groningen, told The Academic Times.

All modern, English translations of the Bible's Old Testament emanate from medieval manuscripts, according to Popović,  but given that the Dead Sea Scrolls are much older than that — more than 2,000 years old — an analysis of the Dead Sea Scrolls "brings us much closer [in time to the writing of the Bible], and even sometimes at exactly the same time as texts from the Bible were being written — one of the most influential books in world history," Popović said.

"So, what I'm studying is that phase of evolution before it became a Bible, and the Dead Sea Scrolls give us a unique vantage point to study that," he said.

Paleography is the study of ancient writing, and one of the most difficult problems in this scientific field is determining writer identity when the writing style of an ancient document is near-uniform, as is the case with the Great Isaiah Scroll, according to the researchers. 

The basic premise behind the investigative design of the present study is that the act of handwriting is an act performed by muscles, and as such, writing is dictated by physics. Muscle movement is person-specific and can be measured through quantitative analysis, Popović said. 

The researchers first developed an artificial intelligence neural network, trained using machine deep learning, that separated the ink text from the background it was written on, keeping intact the ink traces that were made by the original writers more than 2,000 years ago. 

The researchers were then able to examine the microlevel aspects of writing, including measuring the curvature of letters. 

"When you have a straight line, you move faster with your pen; then, when you have to make a curvature, you have to slow down again and speed up,"  Popović said. These muscle movements, among others, result in differences in handwriting. 

Graphically depicting the results of a textural and allographic analysis of the letters on sophisticated scatter plots, the researchers found a "clear separation in the quantified data in two clusters," Popović said, indicating two different cluster groups not randomly distributed throughout the Great Isaiah Scroll with a transition at about the halfway mark of the ancient text. 

An independent, post hoc analysis using heat maps, which aggregate and normalize the average character shape of individual letters from both halves of the ancient text, revealed robust but subtle differences in terms of letter thickness and angular differences. 

The researchers contend that the most straightforward explanation for the differences in writing is that a change of writers occurred, even though the researchers note that a change of pen, writing fatigue or injury of a single writer cannot be ruled out. 

Popović called for more interdisciplinary work to be performed in this field, and noted that the investigative methods used by his team open new possibilities for analyzing the micro-level handwriting of ancient scribes. 

"It is truly amazing, and we've just started with it," Popović said. "It's not a real time machine, but to me, it almost feels like a time machine. You can almost shake hands with these people. We'll never know their name, but through their handwriting, we can almost touch them. And in the end, it's all traced back to the simple idea of muscle movement in writing."

The study "Artificial intelligence based writer identification generates new evidence for the unknown scribes of the Dead Sea Scrolls exemplified by the Great Isaiah Scroll (1QIsa)," published April 21 in PLOS ONE, was co-authored by Mladen Popović, Maruf A. Dhali and Lambert Schomaker, University of Groningen.