Genetic analysis of ancient massacre shows people were killed indiscriminately

Unfortunately, it seems humans have been killing each other since time immemorial. Usually though, when archaeologists find signs of killing, there’s a reason and a pattern to it. But at the Potočani site in today’s Croatia, people were slaughtered indiscriminately 6,200 years ago — and we’re not really sure why.

The Potočani site. Image credits: Novak et al (2021).

“The site of the mass burial at Potočani was discovered purely by chance in 2007,” says study author Mario Novak to ZME Science. “One of the locals from the village was building a garage and the discovery was a result of an erosion caused by heavy rain at the construction site. The subsequent archaeological rescue excavations led by Jacqueline Balen from the Archaeological Museum in Zagreb uncovered a roughly circular pit approx. 2 meters in diameter and about 1 m in depth that was partially destroyed on one side containing numerous commingled human remains.”

At first, the archaeologists thought these were recent remains, from World War 2 or the Croatian War of Independence from the 90s. But there were no modern materials in the pit, just a few pottery fragments. The more researchers looked at the site, the more it seemed like these weren’t modern people at all. There were no dental fillings (a sign of recent provenance) and no modern remains.

Radiocarbon dating of three human bone fragments from the bit suggested a burial date of 6,200 years ago, and also suggested that the people were buried at the same time, not over a longer period of time. It all pointed at the same thing: these people were slaughtered thousands of years ago.

An ancient massacre

The pottery fragments and radiocarbon dating connect this burial to the so-called Lasinja culture. Not that much is known about them, Novak explains. They came in the Middle Copper Age (the Eneolithic) and spread in neighboring Austria, Hungary, and Slovenia.

“There are only a few known burials associated with this culture. We know from material remains mostly excavated from their settlements that they were one of the first people in this part of Europe to start using metal (copper) and that cattle played a very important role in their every-day lives. It is possible these people were semi-nomadic following their herds of cattle,” Novak explains.

“So far, there are dozens of known Lasinja sites known in Croatia but only a few have been thoroughly excavated and investigated,” he adds.

Novak and colleagues were able to retrieve genomic data from the bones of 38 of the 41 individuals found in the mass grave, and in the new study, they published the results. The individuals featured both sexes (21 males and 20 females), and spanned different age groups. Less than half of them were adults, and 11 were children under the age of 10.

Some individuals were linked by family (a younger man, his two young daughters, and his nephew were all found in the pit), but 70% of them were unrelated. The victims do seem to have similar ancestry and seem to have been in the area for a while, so it’s not a case of a new population coming in and getting wiped out. Overall though, there seems to be no clear pattern connecting them — it seems a case of large-scale, indiscriminate killing.

[Also Read: 10,000 Year Old Hunter-Gatherer Massacre Uncovered]

The available evidence is scarce. We don’t know who did this or why. Researchers suspect a fight for resources driven by a change in climate, though it could be an in-versus-out-group conflict (such as targeting of specific families or recent migrants), or even religious ritual.

“Usually, fights over the resources associated with climatic changes and the increase of population is proposed as one of the possible causes. In Potočani, it could be linked with resources, maybe even cattle as it was one of their most important resources,” adds Novak.

This isn’t the first ancient site of this nature, Novak also adds. Numerous sites of this sort have been found in central Europe (Germany, Austria), associated with the so-called Linearbandkeramik culture, some 7,000 years ago. In those cases, violence was aimed towards members of a certain community. In this particular case, it wasn’t an entire community that got wiped out — it was a small part of a larger population that may have numbered in the hundreds.

“In the case of Potočani, we don’t know who might be the perpetrator, but in some other cases from Europe, the attackers were local populations attacking the newly immigrated individuals. Unfortunately, for most prehistoric massacre cases we probably will never get a clear answer to that question.”

We may think of war and massacres as connected to cities, countries, and civilizations — but the results show that large-scale indiscriminate killing isn’t just restricted to modern or historic times, and it’s not even restricted to settled civilizations.

Further research is needed to establish just how frequent this type of violence was and why it happened. Ultimately, this dark episode could help us understand “why such violent episodes occurred in ancient times, but unfortunately are also happening even today,” Novak concludes.

Journal Reference:  Novak M, Olalde I, Ringbauer H, Rohland N, Ahern J, Balen J, et al. (2021) Genome-wide analysis of nearly all the victims of a 6200 year old massacre. PLoS ONE 16(3): e0247332.

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