Some 6,200 years ago, at least 41 Copper Age men, women and children met a brutal end. Killed under mysterious circumstances, their corpses were unceremoniously dumped into a mass grave in what is now Potočani, a village in eastern Croatia.
When archaeologists first rediscovered the remains in 2007, they speculated that the victims were extended family members who’d been executed for unknown reasons. But new research published in the journal PLOS One reveals that most of the deceased had no familial ties, eliminating a leading explanation for their deaths—and prompting experts to once again ask who killed the group and why.
“That’s the one million-dollar question,” lead author Mario Novak, an archaeologist at the Institute for Anthropological Research in Zagreb, tells National Geographic’s Robin George Andrews. “We just don’t know.”
Unless more conclusive physical evidence surfaces, he says, “I don’t think we will ever find out.”
For the study, Novak and his colleagues obtained DNA samples from 38 of the 41 corpses buried in the grave, which measures around 6.5 feet wide and 3 feet deep, according to Live Science’s Mindy Weisberger. (The other three skeletons didn’t yield enough genetic matter for the researchers to evaluate.) Pottery found at the site suggests that the deceased belonged to the Copper Age Lasinja culture.
Per a statement, the team determined that the burial contained the remains of 21 males and 20 females. More than half of the victims were under 17 years old, with 11 children killed when they were just 2 to 10 years old. Radiocarbon testing of the bones dated the mass killing to around 4,200 B.C.
“It is quite probable that these are the unlucky ones who didn't manage to escape,” Novak tells Ars Technica’s Kiona N. Smith. “It is also possible in a few years that we might find another mass burial nearby containing the remains of other members of their community.”
The DNA analysis showed that just 11 of the individuals killed were immediate relatives, notes Live Science. The remaining 70 percent had no direct genetic ties to the other victims but probably shared Anatolian and Western European hunter-gatherer ancestry. As George Dvorsky reports for Gizmodo, the authors suggest that the deceased were all inhabitants of a large pastoral community.
Mass burials of plague victims were fairly common in medieval Europe. But evidence of traumatic wounds inflicted on the Potočani victims points to them dying due to violence, not infectious disease. Though the deceased could have been killed in combat, the absence of defensive injuries to the face and limbs—“[I]f someone attacks you with a club or a sword, you reflexively raise up your forearm to protect the head,” Novak tells Live Science—leads the researchers to think otherwise.
The archaeologist adds, “The only plausible scenario was a massacre.”
Most of the victims suffered blunt force trauma, with three adult men, four adult women and six children sustaining wounds to the sides or backs of their skulls, according to National Geographic. The aggressors probably murdered their targets with weapons like stone axes and clubs.
“We assume that these people were probably kneeling or lying down and were struck from behind,” Novak tells New Scientist’s Karina Shah. “All these injuries were lethal because they don’t show any signs of healing, so their death must have been instantaneous.”
The researchers also determined that the massacre probably wasn’t a planned slaughter, as such scenarios often found enemy combatants killing rival men and taking women captive.
“In this case, it was just random killing, without any concern for sex and age,” says Novak to Live Science.
Per Ars Technica, the team theorizes that an abrupt population increase, a change in the local climate or a sudden decline in resources may have sparked the indiscriminate mass murder.
“At this point we cannot tell with certainty,” Novak tells Ars Technica. “So far, we don’t have any evidence of adverse climate conditions in the region about 6,200 years ago. But this is a completely understudied topic, so we might get some new information in the near future.”