With DNA, Pompeii Narratives Take a Twist

In 79 A.D., a volcanic eruption engulfed a town’s residents. They weren’t all who scientists thought, newly extracted genetic material suggests.

The Italian writer Italo Calvino observed that a person’s life consists of a collection of events, the last of which could change the meaning of the whole. In A.D. 79, the final event for many of the inhabitants of Pompeii was the volcanic eruption that buried them under a 20-foot layer of ash and sediment. Dozens of the corpses retained their shapes long enough for the layers of debris to build around them, forming impressions that, with the decaying of soft tissue, became perfect hollow molds.

Starting in 1863, archaeologists filled the cavities with plaster to create replicas of the victims’ death throes. Narratives were spun around the more evocative casts: a group consisting of a child and two adults, one of whom wore wrist jewelry and whose lap held a youngster, became known as the Family of the House of the Golden Bracelet, while a pair of bodies locked in what appeared to be a poignant embrace were famously named the Two Maidens.

Now, genomic testing on skeletal remains embedded in the casts has challenged both interpretations. As reported Thursday in the journal Current Biology, the DNA evidence shows that the identities and relationships of the deceased do not match the longstanding assumptions, which had largely been based on physical appearance, the positioning of the casts and romantic notions promoted by literature and Hollywood films.

The study team, which included David Reich, a geneticist at Harvard University, and David Caramelli, an anthropologist at the University of Florence in Italy, proposed that the adult and the younger child, traditionally viewed as mother and offspring, are genetically an adult male and a boy who were biologically unrelated. Contrary to the established account, the researchers concluded that none of the four people in the grouping were kinfolk.

“We were able to quite clearly disprove what archaeologists have put forth about this grouping being a nuclear family,” said Alissa Mittnik, a geneticist at the Harvard lab that generated the data. “But of course we don’t really know, and we can’t really say, who these individuals were and how they interacted with each other.”

She added, “It could have been that these were servants or slaves, or the children might have been the children of servants or slaves who also inhabited the house.”

Genomic sequencing also showed that at least one of the so-called maidens, presumed to be either sisters or mother and daughter, was in fact a man. “There again, we could say that one of them was genetically male and they were not maternally related to each other,” Dr. Mittnik said.

She acknowledged that the figures could have been lovers or, given that adoption was a common practice in the Roman Empire, especially among the upper classes, they might have considered each other brothers, or even brother and sister. “So again,” Dr. Mittnik said, “a case where the most obvious or most intuitive interpretation was not, in fact, what we see scientifically.”

Gabriele Scorrano, a University of Copenhagen geneticist who was not involved in the new study, said the findings confirmed and reinforced most of a preliminary analysis of the casts announced in 2017 as part of the Great Pompeii Project, an eight-year program to stabilize and repair the most endangered features of the site.

In that initiative, medical imaging debunked several myths about the casts. A CT scan of one known as the Pregnant Woman revealed that the person was probably not pregnant, and might not have been a woman. An array of specialists speculated that bunched-up clothing accounted for the bulge of the belly. They also determined that some of the victims had most likely died from head injuries rather than asphyxiation.

An estimated 10 percent of Pompeii’s 20,000 or so inhabitants perished when Mount Vesuvius erupted. The first systematic excavations began only in 1748 and proceeded slowly until 1860, when the archaeologist Giuseppe Fiorelli was put in charge. It was Fiorelli who pioneered the technique for fashioning plaster casts. To date, 104 have been made.

Fourteen were examined in the new research. For Dr. Mittnik, one of the most surprising revelations about Pompeii’s residents was their genetic diversity, which highlighted the cosmopolitan nature of the Roman Empire in the period. She attributed that to migration, slavery, conquest and commerce. At the time of the disaster, the Empire’s trade routes extended from North Africa to Asia, and people moved to Rome by choice and by force.

“Some of those from whom we were able to generate genome-wide data showed a more eastern Mediterranean-like genetic ancestry, which could match populations, for example, from the Aegean or from the Levant,” Dr. Mittnik said. “So, they might be either recent migrants or the descendants of migrants from those regions.”

One of the bigger takeaways for Dr. Reich is that visually reconstructing the past is unreliable and sometimes fanciful. “That is a valuable lesson to learn when we’re making measurements of how people are related to each other based on DNA or their molecular sex,” he said. “I think that teaches us some humility and skepticism about our interpretations.”