Ancient DNA has revealed surprises about the identities of some people who perished in the ancient Roman town of Pompeii after a volcanic eruption, overturning misconceptions about their genetic relationships, ancestry and sex. When Mount Vesuvius erupted in AD 79, the volcano spewed hot, lethal gases and ash into the air, slowly killing most of the city’s population.

Ash and volcanic rock called pumice then covered Pompeii and its residents, preserving scenes of the victims of the city’s destruction like an eerie time capsule. Excavations first began to unearth the forgotten city in 1748, but it wasn’t until 1863 that archaeologist Giuseppe Fiorelli developed a method to make plaster casts of some of the Pompeii victims.