Researchers have discovered traces of fern cells in the dental remains of a skeleton found at what was once the medieval necropolis of Can Reiners, on the Spanish island of Mallorca.
“Through analysis of the dental calculus of the skeleton, which we believe dates back to the ninth or 10th century, we were able to determine that the cells were from the fern plant, Asplenium trichomanes,” says archaeologist Dr Elena Fiorin, from the University of York, first author on the new study.
Asplenium trichomanes¸ also known as maidenhair spleenwort, is a common species of fern that grows in rocky areas worldwide.
While it was not surprising to find archaeological evidence of ferns at this site, it was remarkable to find evidence of fern cells in the mineralized dental plaques (dental calculus) of skeletal remains, because it suggests fern leaves had been ingested.
The skeleton was that of a 21 to 30 year old male, and it’s unlikely he consumed fern leaves as part of his diet. After all, there is no written or archaeological evidence to suggest that ferns were part of any human diet, explain the researchers in their new paper. However, there is ample evidence ferns were used medicinally.
“These ferns have been used by herbalists, surgeons, doctors, and other healers for centuries across Europe, but until now we have only had written documents that describe their use,” says Fiorin.
Indeed, she and her colleagues Llorenç Sáez and Assumpció Malgosa at Universitat Autònoma de Barcelona in Spain cite numerous ancient and historical sources, from Pliny the Elder in the first century AD to nineteenth century texts, which describe use of these ferns for treating a variety of ailments, such as alopecia, dandruff and kidney stones.
There is also evidence that A. trichomanes was used as a cough remedy and a laxative in Italian folk medicine, and was also used as an emmenagogue — to stimulate or increase menstrual flow — which means, among other things, that women may have used the plant as a contraceptive.
However, archaeological evidence pointing to medicinal use of A. trichomanes had never been found until now.
“The finding from the dental remains of this skeleton show just how much information we can get from dental calculus analysis,” says Fiorin. “It demonstrates that, in this region of Spain, communities were aware of the medicinal properties of some plants and how to administer them to get the desired result.”
Because the individual in question was male, the use of the fern as an emmenagogue can be ruled out. But beyond this, it’s unclear why he had sought treatment.
The skeleton had no observable pathological lesions that would have pointed to any of the conditions historically associated with A. trichomanes treatment.
But then, they didn’t really expect to find much in that regard.
“Generally, there are few diseases that affect the skeleton and if a person died before bone change occurred, such as cases of acute stages, the skeleton will not show any sign of bony lesions,” the researchers explain in their paper.
Nevertheless, the finding provides more insight into the use of plants in medicinal practice in medieval Europe.
Moreover, says Fiorin, “we now have the potential to look at other dental remains for similar properties that might tell us more about the use of medicinal herbs in the past.”