May 16, 2021

The blue tartar on the teeth of a nun who turned out to be lapis lazuli | Science

The blue tartar on the teeth of a nun who turned out to be lapis lazuli | Science

The tartar accumulated on the teeth of a nun from a small convent of the eleventh century confirms that women were an essential part of the transmission of culture in the Middle Ages. Using sophisticated technologies, European and American researchers have identified among dental plaque particles of the most valuable and rare pigment of that time: the ultramarine blue. Obtained from lapis lazuli, it beautified tables, frescoes (centuries later it would color the sky of the Sistine Chapel) and the most exclusive manuscripts. How did it get to that woman's mouth? The scientists defend that she adhered to her teeth while refining the brush with which she illuminated books.

On this road from the dirtiest to the most beautiful, chance has played its part. "We discovered the blue pigment in the dental plaque by accident", says the researcher of the Max Planck Institute for the Science of Human History (Jena, Germany) and co-author of the study, Christina Warinner. A few years ago, a team led by this expert in ancient human microbiome was analyzing the teeth of human remains found in the cemetery of a small convent of the Augustinians in Dalheim (west of Germany). They were the teeth of a woman, probably a nun of no more than 60 years old, dated by radiocarbon between 997 and 1162 of this era. They identified it as B78.

"We were actually conducting a study on health and diet, looking for microscopic bacteria, starch and pollen in calcified dental plaque," says Warinner. But among the biomolecules of viruses, bacteria and organic material trapped in the calcified calculus, they also found blue particles so intense that they could not be anything other than a mineral. "Once we found it, we wanted to know what it was and then what it meant," adds the German scientist. The current work, published in Science Advances, tells how they managed to identify that blue and suggests how it got to the nun's teeth.

Researchers suggest that the nun made her teeth blue by smoothing the brush with her mouth

To remove the tartar first and then isolate the blue particles from the rest of the dental plaque, the scientists used an ultrasound scan (sonication) not unlike that used by dentists. They found up to 100 particles in the calculus of a single tooth, with an average size of 10 microns, about one tenth of the thickness of a human hair. The highest concentration of particles came from the tartar of the anterior part of the denture, a detail that will help them determine how they got there.

Apart from the loss of two molars and signs of a mild periodontitis, the nun's remains show no signs of illness or trauma that can explain the blueness of her teeth. Suspecting that it could be a pigment, the researchers submitted the particles to two different spectrometry technologies, one using an electron beam (scanning electron microscope or SEM) and another taking advantage of a light scattering effect (micro-Raman spectroscopy). By comparing the spectra obtained with references of other blue pigments they could determine that what the nun had in her teeth was lazurite, the main mineral present in lapis lazuli stones.

"The blue pigment obtained from lapis lazuli was the most expensive in the Middle Ages," recalls the scientist of the London Victoria and Albert Museum, dedicated to the decorative arts, Lucia Burgio. "Until the discovery of America, lapis lazuli was only found in present-day Afghanistan, which explains why it was so precious and difficult to obtain", adds this expert in the analysis of materials of works of art, not related to the study. Burgio also adds that, unlike other blue pigments that degrade over time, such as azurite, the ultramarine blue of lazurite retains its vividness even today.

The professor at Harvard University and one of the greatest American experts in medieval European history, Michael McCormick, extends the relevance and exclusive character of lapis lazuli, lazurite and ultramarine blue: "He came from a single mine in Afghanistan and had to traveling from there in caravans to Constantinople or Alexandria and then bought by the Venetian or Genoese merchants, was shipped by the Mediterranean and finally passed through merchants across the Alps to Germany. "

How did such a special pigment, with a value equivalent to gold, come to the scale of a nun in a small German convent? The researchers acknowledge that they do not know for sure. But they point to four possible explanations and arguments to rule out the first three. One possibility is that the nun would use lapis lazuli as a medicine. Since the Persians and the ancient Greeks, lapidary medicine, based on precious gems, was one of the ways to cure evils. But the first medical treatises in medieval Latin did not appear until the end of the eleventh century. So it seems unlikely that this practice from the east would have reached Germanic lands before the nun died.

Another possibility reminds the outcome of the mystery of the work The name of the rose, by Umberto eco. The blue of the nun could come from the devotional osculation, the habit of kissing the sacred texts. It became so fashionable at the end of the Middle Ages that some liturgical texts were distributed with attached tablets where to kiss and thus not deteriorate them. Although there is evidence of the practice already in the time of the Merovingians (VI-VIII centuries), it would not be usual until three centuries after the death of the woman of the convent of Dalheim.

Although there are other illuminators such as the co-author of 'El beato de Gerona', this study suggests that nuns were not the exception.

Only two alternative scenarios occur to the authors of the study: either the nun made the pigment based on lapis lazuli or she herself wrote or illuminated manuscripts. The trade in Asian lapis lazuli was in the hands of Venetian merchants, who controlled it with an iron hand. The first treaties that explain the complex process of grinding, washing, suspension and filtering to obtain ultramarine blue are also Italian. But they were written very far and long after where the nun lived and died. Although they do not rule out this possibility, the researchers point out that the pigment had already been produced at the convent. So they bet that, in her work of illuminating books, the lady will repeatedly bring the brush to her mouth to refine it before a new stroke. And so he was messing his teeth blue.

"The use of lapis lazuli as a medicine or the devotional ossicles would not produce the patterns of deposition we observe," explains the archaeologist at the University of York (United Kingdom) and co-author of the study, Anita Radini. Instead, he opts for the thesis of the nun write or illuminating, "by the way they are integrated into the tartar: the particles appear in the form of loose powder and its size matches the prepared pigment, not with the lumpy mass [del proceso de preparación]", Add.

If so, it would be one of the first illuminators of medieval books of which there is evidence. It is not the only one, there are great manuscripts, like the Liber Scivias, of the 12th century abbess Hildegard of Bingen or, even older, the Blessed of Gerona, a codex in which part of the miniatures were painted by a nun. But this research reinforces a scenario in which, far from an exception, the participation of women, especially religious women, in the transmission of culture was not an isolated phenomenon.

The medieval history expert and co-author of the Alison Beach study argues that the writing and illustration of medieval manuscripts was a matter of monks, yes, but also of nuns. "Most of the nuns worked in the shade, perhaps under particular spiritual pressure to practice humility, and although many had great skills, like our B78, they would have remained anonymous, women like B78 would have been scattered throughout medieval Europe in this at the time, working in many cases for bishops or abbots beyond their own communities or regions, leaving no trace of their identity as artists. "

His colleague McCormick agrees with Beach: "Scholars had assumed in the past that copying and illuminating manuscripts was a men's issue, but excellent recent research has shown that women played a much more important role than many had thought. "he says and adds:" This new study is the first to physically identify one of these artists mentioned in the letters and records of the time and opens a completely new way to identify the women (and men) artists of that time ".


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