In 2015, the Archaeological Park of Pompeii undertook a project to restore and conserve 86 of the 104 known plaster casts. The project moved almost all of them to an on-site laboratory, where conservators documented surface damage, addressed structural problems caused by rusted iron reinforcing rods inserted in earlier restoration efforts, reattached fragmented pieces, and stabilized the casts with acrylic resin. All 86 casts were laser-scanned to create three-dimensional surface models. Sixteen casts that fit within the scanner were CT-scanned.
This restoration project created an opportunity. The conservators and researchers could access the interior bone and tooth fragments — material that was accessible in cases where previous damage had already exposed it — without further compromising the casts’ integrity. Fourteen individuals from this group of 86 were selected for ancient DNA analysis.
Ancient DNA work is technically demanding in ways that modern forensic DNA analysis is not. DNA degrades over time, and the specific conditions that preserved the gross morphology of Pompeii’s victims — enclosure in hot volcanic ash, subsequent centuries of variable humidity and temperature — were not necessarily favorable for the fine molecular structure of DNA. Authentic ancient DNA is identified in part by characteristic damage patterns: cytosine deamination produces misincorporation signatures at the ends of fragments, creating a pattern that allows researchers to distinguish genuine ancient molecules from modern contamination.
The team extracted DNA from multiple fragments of bone and teeth where available, used contamination controls, and applied the authentication criteria standard in the ancient DNA field. The results for all 14 individuals were analyzed for genetic sex, for ancestry using genome-wide data where coverage was sufficient, and for kinship in cases where multiple individuals from the same site could be compared.