By Claudio Tuniz
Advanced analytical methods, based on radioactivity and radiation, have recently revealed that therapeutic dental filling was in use during the Stone Age. As part of the team that performed the study, I worked with experts in radiocarbon dating, synchrotron radiation imaging, dentistry, palaeo-anthropology, and archaeology. Our discovery was based on the identification of an extraneous substance on the surface of a canine from a Neolithic human mandible.
In May 1911, Josef Müller, a naturalist from Trieste, found an ancient human jawbone embedded in a rock inside a cave near the village of Lonche, in present-day Slovenia. It was bearing a canine, two premolars, and the first two molars. The human remains were then taken to the Museum of Natural History in Trieste (where Müller would later become one of the Directors), and remained there out of the spotlights. A study was indeed published in 1936, which included an analysis by x-ray radiography, but nothing special was noticed, at the time, given the poor resolution of the images. The radiocarbon method had not been invented yet; hence the date of the remains was vague. As a general assessment, this individual was thought to be alive during the Stone Ages, in accordance with other archaeological finds, including remains of animals that are now extinct and some clay artifacts.When we started our study, exactly one century after the discovery of the mandible, all the tools needed for the non-invasive study of the Lonche Man were finally available.
First we obtained a high-resolution 3D virtual image of the full mandible using X-ray computed micro-tomography, a method similar to hospital CT scanning, but with a much better resolution. The images revealed that the canine had a long vertical crack. In addition, an area of enamel had worn away to create a large cavity, exposing the dentine (and thus producing a terrible pain!). To improve the 3D image we used a particle accelerator, called synchrotron, which was available in Trieste. This large facility, Elettra, produces an intense flux of X-rays, dramatically increasing the imaging performance. When we focused the synchrotron radiation beam on the canine, we noticed that some extraneous material was forming a thin cap that filled the cavity of its crown.
At this point we extracted a minute amount of the filling material from the canine and used a technique called infrared-spectrometry (that you can sometimes see in TV movies for crime scene investigations). This analysis provides ‘chemical fingerprints’ to identify materials of interest. After our visual inspection, we were convinced that the extraneous substance was some kind of natural resin, but infrared spectrometry analysis showed that it was beeswax.
To rule out a later post-mortem intervention, we had to fix the chronology of the materials under study. When you have organic substances, radiocarbon is the most precise dating method available. Using atom-counting techniques, the so-called accelerator mass spectrometry, only a minute amount of sample is necessary. To be sure, the radiocarbon analysis was performed in two independent laboratories. A bone sample of about one gram was collected from the mandible using a hand drill; its collagen was then extracted and subsequently measured in an Italian laboratory. The tiny beeswax sample (about one milligram) was dated in Australia. Radiocarbon measurements confirmed that both the mandible and the beeswax filling were about 6,500 years old, with a very small error range.
We had found the smoking gun! This was the earliest known example of therapeutic-palliative dental filling, going back to the Neolithic. The so-called Vlaška people, living then near the northern shore of the Adriatic Sea, used beeswax to fix their dental problems. Probably this was a common necessity, as it is well known that in the Neolithic humans were extensively using their teeth as tools, for weaving and other extra-masticatory activities.
Claudio Tuniz leads a programme on advanced x-ray analyses for palaeoanthropology at the Abdus Salam International Centre for Theoretical Physics. He was Assistant Director of the Abdus Salam International Centre for Theoretical Physics in Trieste . Previously he was Nuclear Counsellor at the Australian Embassy to the IAEA in Vienna and Director of the Physics Division at the Australian Nuclear Science and Technology Organization in Sydney. He is co-author of the book The Bone Readers (2009), and the recently published Radioactivity: A Very Short Introduction (2012). Read his blog post: How radioactivity helps scientists uncover the past.
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Image credits: courtesy of ICTP.