Pompeii’s plaster cast human figures aren’t who they were assumed to be, genetic tests have revealed, highlighting the way idealised stories can be projected onto archaeological evidence.

The analysis also reveals that the demography of Pompeii was also far more complicated and diverse than previously thought.

When Vesuvius erupted in AD 79, it buried several Roman towns, including Pompeii. Many of Pompeii’s residents were completely smothered in compacted ash during the eruption and, as their bodies decayed, cavities formed that perfectly preserved their positions in their final moments.

In the 19^th century, archaeologists developed a method of pouring plaster into the cavities to make life-like casts. Since then, more than 100 of these casts have been made, preserving the victims’ shapes along with any remaining bones that hadn’t decayed over the centuries.

However, it has long been known that many of the plaster casts were manipulated into different poses and sometimes placed together to add to the drama of the Pompeii story, says Valeria Amoretti at the Archaeological Park of Pompeii in Naples, Italy.

To learn more about who these people were, Amoretti and her colleagues examined 14 of the plaster casts and extracted DNA from bones in five of them.

What they found has completely altered the established interpretations of who they were. An adult wearing a golden bracelet with a child on their lap was long believed to be the child’s mother. The DNA analysis shows they are actually an adult male who is biologically unrelated to the child. A nearby figure, formerly interpreted as being the father, was also unrelated to the supposed mother and child.

Another pair, who were thought to be sisters or a mother and daughter who died in an embrace, included at least one genetic male and were also unlikely to have been related.

The genetic analysis further revealed that the people of Pompeii had diverse ancestry, with components related to modern eastern Mediterranean, Levantine and North African Jewish populations.

Amoretti says it is no surprise that the Roman world was multicultural, and that the Mediterranean and its ports united people.

“But it is extremely interesting to discover the extent of this melting pot, even in an average provincial town like Pompeii, and to have scientific proof of it from ancient DNA,” she says.

Alissa Mittnik at Harvard University says the study highlights the importance of applying science before interpreting archaeology at face value.

“Ultimately, it reminds us that the most intuitive, dramatic or sensational explanations do not always hold true, encouraging us to stay aware of and question our preconceived notions,” she says.

A possible ancient shoreline has been found in the region of Mars explored by the Chinese rover Zhurong, providing further evidence that an ocean may once have covered a vast area of the lowlands in the planet’s northern hemisphere.

The rover landed in southern Utopia Planitia in May 2021 and remained active for almost a year. Researchers studying data from the rover have found hints of an ancient ocean or liquid water as recently as 400,000 years ago.

Now, Bo Wu at Hong Kong Polytechnic University and his colleagues have conducted a comprehensive analysis of the topographic features in the landing area, combining remote sensing data from satellites with observations from the rover.

They say they have found features consistent with the existence of a shoreline in southern Utopia, including troughs and sediment channels. They also dated and identified the composition of surface deposits in the area. Based on this, the team thinks the ocean existed 3.68 billion years ago, but froze and then disappeared around 260 million years later.

“The findings not only provide further evidence to support the theory of a Martian ocean but also present, for the first time, a discussion on its probable evolutionary scenario,” says Wu.

The area can be divided into a shallow section to the south and a deep section in the north. Even the shallow part of the ocean may have been up to 600 metres deep, says Wu, but there isn’t enough data to estimate the maximum depth of the ocean.

“Water is a key ingredient for life, and the past presence of an ocean on Mars raises the prospect that Mars once might have been capable of harbouring microbial life at its early stage,” he says.

Mathieu Lapôtre at Stanford University in California says whether oceans existed on early Mars is a highly contentious question with critical implications for the planet’s past habitability. He says future missions will need to test the findings of this new research.

“Utopia Planitia may constitute an invaluable record of early Mars’s near-shore and coastal environments,” says Lapôtre.