When was the Hebrew Bible written? That question has long been the subject of heated debate, largely because of the fragmentary nature of the historical record. Piecing together the ancient history of the Hebrew-speaking peoples revolves around a limited number of inscriptions and physical artifacts, along with written accounts from neighboring civilizations. Of course, there are also the Biblical texts themselves, but the oldest of these, found among the famous Dead Sea Scrolls, date back only to the 3rd century BCE.

Now, a cross-disciplinary team of nine Israeli scientists from Tel Aviv University has taken a fresh look at a collection of inscriptions from circa 600 BCE, and—with the help of a machine-learning computer algorithm—has concluded that literacy was already on the rise in the ancient Kingdom of Judah (a.k.a. Judea) in the years prior to the Babylonian conquest in 587 BCE. And that, they argue, points to an “educational infrastructure” that would have made the writing of the Biblical texts possible. Their study was published today in the Proceedings of the National Academy of Sciences

The computer program studied the inscriptions from 16 pottery fragments recovered at Arad, a remote desert fortress about 20 miles south of Jerusalem, the capital of the kingdom. The analysis of the handwriting showed that at least six different writers penned the inscriptions, which contain instructions for the movements of troops and the distribution of supplies, including wine, oil, and flour. They’re addressed to someone named “Eliashib,” believed to have been the quartermaster of the fortress, and to his assistant.

Shira Faigenbaum-Golovin et al. in PNAS

“Until now, there was no conclusive empirical evidence about levels of literacy [in Judah],” Arie Shaus, a Ph.D. student in applied mathematics at Tel Aviv University and one of the lead authors of the study, tells mental_floss. Now there’s “very good evidence that hundreds of people, maybe more, could read and write.”

What's unclear, though, is whether reading and writing was restricted to a small group of elites—say, a handful of priests and scribes, perhaps in Jerusalem—or was more widespread. Shaus suggests it was quite common in the military. “We can now say that writing is everywhere, from the upper echelons of the Judahite army, down to the level of vice-quartermaster of some remote, isolated fort,” he says.

A chart depicting the hierarchy of the correspondents in the Arad inscriptions. Image credit: Shira Faigenbaum-Golovin et al. in PNAS

While many previous studies have attempted to date the various Biblical texts directly, this study turns the problem on its head, Shaus explains: “Instead of asking when were the texts written, you ask when would it have been possible for such texts to have been written.”

Christopher Rollston, an expert on ancient Semitic languages and literature at George Washington University, describes the technique used in the study as “very promising.”

“Determining the number of writers is really useful,” he tells mental_floss. Rollston, who was not involved in the current study, notes that scholars have long attempted such estimates, using various “analogue” methods, but this study provides an “empirical foundation.”

Rollston cautions, however, against assuming that the general population of Judah could read and write. “Literacy in ancient Israel and Judah was probably 15 or 20 percent of the population, at most,” he says.

According to the Bible, a unified Hebrew-speaking kingdom flourished under King David and his son, Solomon; historians estimate that their reigns spanned roughly 1000 to 920 BCE, when the kingdom was divided into Israel, in the north, and Judah, in the south. The northern kingdom eventually fell to the Assyrians, the southern kingdom to the Babylonians. Although Hebrew inscriptions dating back to the 10th century BCE have been found, the dates associated with the Biblical texts have always been the subject of debate. The Book of Deuteronomy, for example, is a complex work unlikely to have been composed until literacy was fairly widespread, historians believe.

This research “emphasizes the political and military infrastructure that allows for the spread of writing literacy across different social classes,” William Schniedewind, an expert on Biblical studies and Semitic languages at UCLA, tells mental_floss. “That’s the important thing here—it’s not just that you have writing; it’s that you have it across a variety of social classes, so that it can be socially significant.” Schniedewind says that the Tel Aviv study supports the thesis of his book How the Bible Became a Book, published in 2004.