The city of Pompeii—buried by an eruption of Mount Vesuvius in 79 CE—has been intensively studied for decades. The sudden tragedy transformed it into a glimpse of life during the Roman Imperial Age, frozen in time, which has yielded novel insights into the architecture, customs, and language of the era. But one goal has remained out of reach: sequencing the whole genome of any Pompeian. Scientists have been attempting to do so for years in the hopes of learning more about the population who once lived there, for example, where they came from, or what diseases they suffered from.
Now, thanks to improved genomic technologies and interdisciplinary collaboration, a diverse group of researchers has finally achieved the feat. They announce today (May 26) in Scientific Reports the bioarchaeological and genomic analyses of two adults (a man and a woman) found at a Pompeii building named Casa del Fabbro, translated as House of the Blacksmith. Based on the condition of the DNA, though, only the man’s genome could be sequenced, albeit at low quality.
Short fragments of ancient human and animal DNA from the site have been reported previously, explains coauthor Gabriele Scorrano, a palaeogeneticist currently at the University of Copenhagen who carried out this work while at the Tor Vergata University of Rome. But recovering enough material to assemble a complete genome from the destroyed city is challenging, he adds. Those individuals have long been covered by the ashes of the eruption, which means “the bones have been exposed to high temperatures” that can damage them and any DNA preserved within.
Advances in technologies for extracting and sequencing ancient DNA motivated Scorrano and his colleagues to pursue the task on two individuals from the site—a man who was likely in his late thirties and a woman over 50 years old when Vesuvius erupted, both found leaning on the remnants of a sort of couch in a corner of what was likely the dining room of Casa del Fabbro. Ancient DNA researchers today are also better informed as to which kind of bones are best for the molecule’s extraction, says Scorrano. For instance, the petrous bone, which protects the inner ear, yields exceptionally high concentrations of human DNA, as it is the densest bone in mammals. “We were lucky because, in both of the samples, we had petrous bones,” he says. Still, the quality and quantity of the woman’s DNA were not sufficient to assemble her genome.
The man’s genome assembly had just 0.42x coverage, indicating that the reads had little overlap, and there were gaps. Still, according to Scorrano, the sequence was good enough to analyze certain aspects of the DNA. The results suggested the Pompeian man was genetically similar to modern Mediterranean populations and, when compared to other published genomes from ancient Rome, that he was closely related “to Imperial Roman Age individuals,” Scorrano says, adding that that’s what the team expected to find. But at the same time, he notes that Rome was packed with people from diverse genetic backgrounds back then. In fact, the markers of the man’s maternal and paternal lineages were absent among those previously published sequences, which suggests the region had high genetic diversity during that time.
The Italian Peninsula was “incredibly heterogeneous” when Vesuvius erupted—people were “coming from all over the empire” into Rome or into port cities like Pompeii, says University of Chicago archaeologist Hannah Moots, who did not participate in the study but has previously characterized the genomic pool of ancient Rome. It is exciting to have genomes from Italian regions outside Rome, she says, adding that looking at sites like Pompeii is “really interesting” because they can provide insights into more rural areas.
The authors of the new study also report that the man could have been affected by spinal tuberculosis, based on the destruction of a fragment from one of his lumbar vertebrae, together with other bone morphological markers. Motivated by this diagnosis, the team searched for ancient DNA from Mycobacterium tuberculosis, the bacteria causing the disease. They did find sequences that could be associated with this bacterium. Scorrano explains that it’s impossible to be sure, given the high level of similarity among members of the Mycobacterium genus. Yet the overall evidence strongly points toward that disease, the team concludes in the paper.
See “TB over Time”
Medical histories aside, the team’s archaeological and genomic analyses also helped piece together the personal narratives of the two Vesuvius victims. University of Salento anthropologist Serena Viva, coauthor of the new study, writes in an email to The Scientist that the findings “also sought to explain why the two individuals, given their original position, did not attempt to escape, unlike many others during the eruption.” According to her, “the answer lies in their health condition and advanced age.” Based on the form of tuberculosis diagnosed by the team, the man likely had “little mobility,” while analyses of the woman’s bones presented in the paper indicate she “was elderly and suffered from arthrosis, so she stood there waiting, protecting a small treasure of coins,” she writes.
“It is very interesting for us to reconstruct the personal history of two protagonists of one of the world's best-known catastrophic historical events,” Viva concludes.