The emergence of states caused a spike in violent deaths 6,400 years ago

Human beings have a nature that seems paradoxical. They’re capable of large-scale cooperation or altruism with strangers, yet they can also display extreme levels of violence. This hybrid nature challenges those who believe that interpersonal violence is intrinsic to human societies, as well as those who think that there was a peaceful paradise on Earth before the arrival of agriculture.

To contribute data to this debate, Joerg Baten, Giacomo Benati and Arkadiusz Sołtysiak have studied the signs of violence, by looking at broken bones and skulls in more than 3,500 human skeletons. These marks — caused by weapons — were examined carefully, after they were excavated from various sites in a wide region of the Middle East, from present-day Turkey to Iran. In total, according to an article published this past Monday in Nature Human Behavior, the researchers have covered a period that began about 14,000 years ago, when agriculture and livestock began to develop, until the year 400 BC, before the beginning of our era. This was around the time when the Greek geographer Herodotus began the practice of historiography.

The remains that have been found show that the violence fluctuated over the centuries. Starting from relatively low levels at the dawn of civilization, it increased with the complexity that accompanied the first agrarian societies. It’s believed that human hunter-gatherer groups could avoid conflict more easily, because there were so few of them.

And, during the Neolithic period — as agricultural technology spread — population density still remained low. However, something seems to have changed about 6,400 years ago, in the Copper Age. As the authors explain, an increasingly dry climate could be one of the factors that favored urbanization in the Middle East, with migration from the countryside to the main cities. This resulted in competition for resources between the elites and the masses.

It was in that same period that the first states began to appear — ones that still didn’t have the strength to manage conflicts between their inhabitants. In fact, these centralized political systems actually increased conflict between groups on a large scale. This combination of factors may explain why those first steps towards state organization resulted in the highest spike in violent deaths in the more than 13,000 years covered by the study.

After those centuries of greater interpersonal violence, the archaeological record shows a decline for 1,500 years, from 4500 to 3000 BC. During this period, states perfected their organization: they obtained resources through taxes and were able to control social violence. They did this partly through military control, but also by encouraging cooperation through religious festivals and other projects, such as the construction of temples or palaces, which fostered the feeling of belonging to a society. Such a feeling among citizens contributed to the reduction of conflicts.

As violence got under control, it increased again during the transition to the Iron Age, about 1,500 years before our era. During that period, a three-centuries-long drought — which caused food shortages and population displacement — was added to the rise of warring superpowers, such as the Assyrian Empire, who targeted neighbors with ruthless military campaigns and mass deportations.

Giacomo Benati, a researcher at the University of Barcelona and the main author of the study, says that works such as these help to complete an understanding of the variations in violence during a historical period that is less known than more recent ones. It’s also fundamental to understanding which factors exacerbate conflict. For instance, one of the findings of the study is that rising inequality doesn’t necessarily encourage violence.

“There’s evidence that inequality can trigger conflicts, but in our data, we see that, during the Bronze Age, inequality increased, yet violence decreased,” Benati points out. In this period, the professionalization of war can also be observed. Burial grounds reveal large quantities of weapons, which could have meant that — although there were high levels of conflict — the wounds associated with violence were less frequent among groups who didn’t belong to the warrior caste.

The researcher also emphasizes that, along with material aspects, there are ideological factors that could influence the increases or decreases in violence. “Culture, human capital, religion, or morality can all have an impact. But, in the absence of written testimonies, it’s almost impossible to access the way of thinking in prehistory. We stick to the variables that we can measure,” Benati explains.

Finally, on the question of whether humans are more inclined toward cooperation or conflict, Benati affirms that “we’re [inclined towards] both. In the archaeological record, we see that there has always been cooperation, to build cities and live together in large groups. Yet, there’s also conflict. By making these maps that show variations in conflict and trying to understand what variables fuel conflict, we’re better able to understand which circumstances provoke violence, or prevent it.”

“We now know that institutional organizations and legal systems can help manage conflict within a society and reduce violence. [We also see] that climate changes or urbanization can increase it,” he concludes.

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