Historians have long known that the Romans sometimes covered their dead in liquid gypsum, a mineral used in plaster, before placing the bodies in their tombs. Still, the ritual—and the reasons behind it—have left researchers baffled.
Now, for the first time, scientists are using 3D scanning technology to gain a better understanding of the practice. Researchers from the University of York, the York Museums Trust and Heritage360 examined a grave in which two Roman adults and one child were buried some 1,700 years ago. They unveiled their findings at the York Festival of Ideas on June 3.
Based on how the bodies were once positioned, researchers think the individuals were two parents and a child who all died at the same time. After so many years, the imprint left in the gypsum is all that remains.
“The contours of the three individuals in the gypsum can be seen with the naked eye, but it is difficult to make out the relationship of the bodies to each other and to recognise how they were dressed or wrapped,” says Maureen Carroll, an archaeologist at the University of York, in a statement. “The resulting 3D model clarifies these ambiguities in stunning fashion.”
Based on the scans, the team found that each body had been wrapped in “shrouds and textiles of varying quality and weave” before being covered in gypsum. Analysis of resins in the coffins reveal that the materials were expensive, indicating that the practice was reserved largely for members of the upper class.
“The Roman family gypsum casing is particularly valuable because neither the skeletons, nor the coffin, were retained after their discovery in the 19th [century],” Carroll tells Live Science’s Hannah Kate Simon.
She adds that the casts can provide historians with more information than the skeletons would have. “We are very lucky to have this casing, as it shows the precise position of the bodies and their relationship to each other exactly at the moment when the liquid gypsum was poured over them and the lid of the coffin closed about 1,700 years ago,” she tells the publication.
According to the researchers, gypsum burials have been found elsewhere in Europe and North Africa. They are particularly common in England, and the area around York has the highest known concentration. The Yorkshire Museum holds the largest collection of the gypsum casts from Britain.
In ancient Rome, standard burial practices shifted throughout the centuries. With time, as more territory fell under Roman control, cultural practices from other parts of the world began to influence daily life. Eventually, intact burials became more common than cremation, which had been practiced for many years. Early Roman laws decreed that no tombs could exist within the city walls, so the highways leading up to the city were lined with tombs.
Looking ahead, the team from York plans to scan all of the casts in the Yorkshire Museum’s collection and learn more about the age, sex, diet and geographic origins of the individuals the gypsum once covered.
While many questions remain, the gypsum burials provide present-day historians with “precious evidence for perishable materials that rarely survive in Roman graves,” write the researchers.