Researchers use a micro-CT scanner to decipher cuneiform writing thousands of years old for the first time. NEMO Kennislink spoke with technicians from Delft and an Assyriologist from Leiden who made new discoveries through a combination of specialisms.
While our ancestors built the last Dolmens, in the third millennium BC, the city of Ur in present-day southeastern Iraq already had an extensive administration and bureaucracy. Ur was the capital of the then Sumerian Empire. That administration, intended to register taxes from all provinces, has been handed down via about a hundred thousand clay tablets. Thereupon the Sumerians wrote in the cuneiform script known to us. Their mother tongue, Sumerian, is the oldest surviving language. And that has everything to do with the shelf life of their writing materials.
The clay tablets were excavated decades ago in Iraq and spread all over the world. Yet these are only part of the administration of the Ur III Empire (2110-2004 BC), named after the Third Dynasty of Sumer. There must be much more underground in Iraq. The clay tablets that we have available date from the year 2000 BC, and thus provide a unique look back in time. Part of it is located in Leiden.
The wheat chaff
“Leiden has a collection of about three thousand clay tablets,” says Rients de Boer over a cup of coffee in a cafe in Leiden. “They are kept in a safe on campus.” De Boer is an Assyriologist and until recently worked for Leiden University, where he was also curator of the clay tablets that are managed by the University's Netherlands Institute for the Near East. The collection was brought together in the 1930s by a professor and contains clay tablets of different genres and from different periods. But soon they will be transferred to the National Museum of Antiquities. “All the beautiful material has been taken out and published, especially literary texts. What remains is a mass of administrative texts:receipts, deliveries. The chaff that remains. And because such an administration is never complete, it is not of much use.”
Nevertheless, De Boer was interested in those administrative clay tablets during the period that he was a curator. Perhaps it was because of his background:before studying Assyriology, he completed a degree in economics. But the original idea to further investigate some of those clay tablets came from his Delft colleague Dominique Ngan-Tillard, with whom he was collaborating at the time for an exhibition on Syrian heritage in the National Museum of Antiquities. “She had seen that there were also clay tablets in envelopes, and saw an opportunity with the micro-CT.”
Unlike the other clay tablets, these were in a clay envelope, making the contents illegible. This was mainly done to prevent fraud, for example in sales contracts, explains De Boer. The envelope then contained more or less the same text as the clay tablet, but the original was inside. “Imagine:a Sumerian buys a house on a plot of 100 square meters, only to find out that his living space is only 90 square meters. At that point, he can break the sealed envelope to verify the claim. The envelope makes it impossible for the seller to change the text.” It was otherwise quite easy to change that with clay, especially because it was often not fired, but was only left to dry in the sun.
Look through the envelope
Now, thousands of years later, many of those clay tablets are still in their envelopes. Assyriologists are naturally very curious what it contains. When you open them, there is a high risk of damage. “With our CT scanner, it is possible to decipher what is in the envelope without opening or damaging it,” says Dominique Ngan-Tillard of the geo-engineering department at TU Delft. She points to a white appliance about the size of a refrigerator tilted on its side.
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Before the tablets enter the device, they are first placed in a cardboard coffee cup. This may sound like an odd combination of high-tech (CT scanner) and low-tech (coffee cup), but Ngan-Tillard stresses that it works just fine. “Why make an expensive holder when a cheap coffee cup also works?”
Ngan-Tillard slides open the scanner's hatch on the side. Inside we see a plateau where the cup with clay tablet goes on. On the side is a yellow tube:that is the source that fires X-rays at the cup. On the other side is a dark plate, which receives the rays. In this way, the device checks what is between the source and detector and in this way looks through the envelope, as it were. “It works just like a CT scanner in a hospital that doctors use to look inside your body,” says scientist Lambert van Eijck of the Delft Reactor Institute. He also participated in the investigation.
In this way the scientists unravel the messages that have remained secret for thousands of years in the envelopes. Ngan-Tillard shows on her computer how to digitally peel off the envelope so that she can read the message on the tablets. Usually these are not very exciting messages, but they are contracts. Yet there are also juicy stories every now and then. Ngan-Tillard points to an unopened letter. In it, an Assyrian merchant is angry at how his mother treats her staff.
Levels of literacy
So a letter could have been written by an angry son, but also by others. The writers are diverse, explains De Boer. Literacy was actually quite high at that time. The difference from now was that your levels of literacy had levels of literacy. “On the one hand, you had professional writers. A kind of craftsmen, who also passed this craft on to their children. There were also temples and palaces that employed scribes to conduct their records. But in addition, there were also many traders and other people who could read and write to a certain level. For example, if you do the administration of a grain silo, you only need a limited repertoire of characters. This is in contrast to a court scribe who has to write difficult hymns for the king.”
After the CT scan, the researchers make a 3D print of the clay tablets. There are about twenty of them on Ngan-Tillard's desk. They are surprisingly small and fit easily in the palm of your hand. They often have the shape of a rectangle and bulge somewhat like a pillow. She shows one. Everything is described. Not only the front and back, but also the narrow sides are full of characters. With such a 3D print, scientists can study them well without damaging the original.
Plant remains that are thousands of years old
But it is not only the written texts under the envelopes that are interesting for science. Because the tablets themselves contain even more information. The scientists can also look at the composition of the clay. “With the CT scan, we discovered that there are plant remains in the clay,” says Ngan-Tillard. “The Assyrians probably did that to make the clay more solid. A botanist from the University of Groningen studies the plant remains. This is valuable information, because it gives us a better idea of what was cultivated thousands of years ago.”
The material itself reveals even more secrets. “We are also investigating the way in which cracks appear in the clay,” says Ngan-Tillard. “That tells us how clay behaves over a longer period of time. This allows us to increase our knowledge of the material. That also helps us, for example, if we use clay in dikes.”
What started as a project to decipher cuneiform writing has grown into much more. And this isn't the last thing the scientists are investigating, either. "We want to look at the chemical composition of the clay," says Van Eijck. "We do this not only with the CT scanners, but also with other scanning devices in the Reactor Institute of the TU Delft. In this way we determine from which region the clay is coming and what kinds have been used. “And maybe we'll discover more, which we can't think of right now.”
Ngan-Tillard zooms in on a 3D image of a scanned clay tablet on her screen. “See it denting a bit at the bottom? I think it's the print of a finger. That's how detailed we can see everything now. It is sometimes as if we are looking over the shoulders of the makers of these tablets.”