Archaeologists Uncover Evidence of Ancient, Indiscriminate Mass Murder

Genetic analysis of skeletons from 6,200 years ago, found in a pit in Croatia, shows the victims were unrelated: Men, women and children appear to have been brutally slaughtered en masse

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The Potočani mass burial, with the upper layers of the pit showing numerous commingled skeletons (Novak et al, 2021, PLOS ONE)
The Potočani mass burial, with the upper layers of the pit showing numerous commingled skeletons (Novak et al, 2021, PLOS ONE) Credit: Novak et al, 2021 / PLOS ONE

Humanity has a history of violence that probably goes back to the dawn of its existence. When confronted with the earliest cases of mass murder, modern experts can usually tease out some motive for the carnage, make some sense of what appears to be senseless killing: conflict over resources; human sacrifice; locals slaughtering an immigrant population (or vice versa).

This does not appear to be the case for the dozens of men, women and children who were brutally executed and unceremoniously dumped into a pit some 6,200 years ago in what is today Croatia. The 41 victims, piled atop one another in a hole just two meters in diameter, were uncovered in 2007 in the village of Potocani, when a local resident decided to build a garage.

Many of the skeletons, radiocarbon dated to 4,200 B.C.E., showed unhealed fractures in the back of the skull, suggesting that these people had not died in battle, but had been executed in cold blood. A genetic analysis of the human remains, published Wednesday in the journal PLOS ONE, was meant to provide some clue as to why this particular group had been targeted.

Instead it has left researchers scratching their heads over what appears to be a case of large-scale indiscriminate killing.

“What’s interesting is that there are no surprising results,” says Prof. David Reich, a Harvard University geneticist and one of the world’s top experts in the study of ancient DNA. “Genetically, this looks like a vanilla cross-section of what you would expect from society in this time and place.”

Prehistoric cold cases

After sequencing the DNA of 38 out of the 41 skeletons, the researchers found that the victims’ genetic makeup was typical of members of the local Lasinja culture, a population that lived between today’s Croatia, northern Bosnia, Slovenia and southern Hungary during the Copper Age.

Three perimortem penetrating injuries to the skull of a young adult female from PotočaniCredit: M. Novak / Institute for Anthropological Research

While there were some families among the dead, most of the individuals were unrelated to each other, suggesting they came from a much larger group of hundreds of people whose fate remains unknown, says Dr. Mario Novak, an anthropologist from the Institute for Anthropological Research in Zagreb. Combined genetic and morphological data also showed the tomb contained an equal distribution of males and females throughout all age groups. Roughly half of the victims were teens and children, with the youngest aged between two and five years old.

This is all very strange because, when studying ancient massacres, researchers usually detect some statistical commonality in one of these categories – genetics, age, sex – that can help them provide an explanation for the finds (which of course doesn’t make them any less grisly).

For example, mass killings of children can often be associated with ritual sacrifice, for instance as practiced by multiple pre-Columbian civilizations like the Maya of Mexico and the Chimu of Peru.  Conversely, a preponderance of adult males in a mass grave may signal that they died during or in the aftermath of a battle.

This is thought to be the case for a 7,000-year-old mass grave found in Talheim, south-west Germany, where local young women appear to have been spared execution by an attacking force, presumably, researchers speculate, because they were taken captive.  A disproportionate amount of young male skeletons showing signs of having met a violent end has also led scientists to identify a major battlefield from some 3,200 years ago on the Tollense River, near the Baltic Sea. The amount of bodies recovered there, at least 130, makes this the largest known conflict site for the European Bronze Age. Who clashed there and why is not clear (there are no written records from the time in this region) but experts say that two armies numbering in the thousands must have met in battle, with warriors believed to have come from across Northern Europe taking part in the fight.

Genetics also play a key part in investigating these very, very cold cases. We now know that in some cases of prehistoric mass killings, specific families were targeted, as shown by genetic testing on a 5,000-year-old mass grave in Poland, which showed that the 15 victims were all related. Another recent study involved the nine Neolithic people whose bodies were found in a cave in the Spanish Pyrenees: they had been shot to death with arrows and then mutilated some 7,000 years ago. The DNA analysis showed the victims were immigrants, descendants of early farmers from the Near East, who may have been massacred in a xenophobic attack by local hunter-gatherers

Finally, dozens of skeletons uncovered at Jebel Sahaba, in Sudan, are dated to some 13,000 years ago and are considered victims of the first known outright war. Here too, based on differences between the warring sides’ morphologies, researchers suspect there was a racial element to the violence between two groups, perhaps compounded by conflict over scarce water. 

Jug typical of the Lasinja culture found in Potocani mass burialCredit: Igor Krajcar / Archaeological Museum in Zagreb
Potocani, CroatiaCredit: Google maps

None of these scenarios can explain the slaughter at Potočani. The victims didn’t belong to a single extended family, or a particular age group or sex.

“It just seems like a group of people were randomly corralled and killed,” Reich tells Haaretz. Given that we only have the bodies of those who were brutally executed, we know nothing about the perpetrators. Still, there is no evidence that the genetics or material culture of the region changed after this event, so we can surmise that those responsible were not invaders from a distant land but rather a neighboring group.

The more things change

Some experts have suggested that the numerous massacres in Neolithic Europe were driven by a combination of climate fluctuations and population increase, which triggered fights over resources, Novak notes.

The Lasinja (named after a village in Croatia where this prehistoric culture was first identified) were a semi-nomadic people whose economy and lives revolved around cattle herding, he says.

So it is possible that the Lasinja found at Potočani were attacked by a rival tribe who wanted to seize their cattle and pastures, but that still doesn’t explain the indiscriminate nature of the killing.

“In this kind of attacks you would expect male adults and perhaps children to be slaughtered, while at least the younger females would be taken captive, but in this case they were also killed,” Novak says.

Perimortem blunt force cranial injuries in two individuals from Potocani: (A) Boy aged 11-17 (B) Young womanCredit: M. Novak / Institute for Anthropological Research

While most of the skulls show a single blunt-force trauma to the back of the head, some of the victims were clubbed up to four times, Novak tells Haaretz. This apparent “overkill” highlights the fury behind what seems like a broader attempt to wipe out an entire community, the anthropologist notes. “It almost looks like a genocide, or at least intentional killing on an industrial scale,” he says.

We may never know what drove the slaughter at Potočani so many years ago. But it is perhaps no surprise that, when the pit was first uncovered, archaeologists thought they had stumbled upon a mass grave from World War II or the interethnic conflicts that accompanied the breakup of Yugoslavia in the 1990s. The experts of course quickly realized they were dealing with prehistoric events. Yet, for the untrained observer, the sight of innocent people piled up in a shallow pit makes it hard to shake off parallels with modern atrocities and the sinking feeling that, over thousands of years, humanity hasn’t changed that much.