Study Shows Neolithic Population Declines Linked to Fear of Warfare

In the first few thousand years after the end of the last Ice Age, humanity experienced some curious and surprisingly rapid population crashes.

While population crashes in ancient times have often been linked to epidemics, environmental changes and natural disasters, scientists are certain there were other causal factors that contributed to population fluctuations. In a new study just published in the Journal of the Royal Society Interface, a team of scientists led by experts from the Complexity Science Hub (CSH), a research institute in Vienna, presents evidence that exposure to warfare and other types of societal conflict played a major role in causing population losses in Europe during the Mid-Holocene era (between 5,000 and 3,000 BC).

Factoring in Fear

This new research did not focus on the loss of life associated with combat. It instead looked for evidence to show that the fear of conflict’s effects was enough to provoke large-scale ancient population movements across the vast Eurasian landscape, which in turn had a longer-term impact on the overall level of the human population.

The study authors wrote in their journal article:

“Beyond direct battle casualties, conflicts can also create a ‘landscape of fear’ in which many non-combatants near the theaters of conflict abandon their homes and migrate away…. This process causes population decline in the abandoned regions and increased stress on local resources in better protected areas that are targeted by refugees.”

By using the phrase ‘landscape of fear’ to describe what was happening, the CSH researchers have created a new conceptual framework for measuring the impact of warfare on migration patterns in the past, and by extension in the present and future as well. They also linked the concept of overpopulation and the overconsumption of resources, which would have led to a decline in the real numbers of humans over time.

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Group of prehistoric hunters armed with spears and axes. (Mars0hod/Adobe Stock)

When Archaeology Validates the Computer Model

For the purposes of this study, the Complexity Science Hub researchers and their associates developed a computer model based on their theory that the fear of conflict would have a meaningful impact on ancient demographics and migration patterns. They hoped their model would align with data collected from various European Mid-Holocene archaeological sites, which would need to show a clear connection between population fluctuations and exposure to conflict zones.

It is not easy to estimate population levels at sites that were occupied thousands of years in the past. To get as close to the truth as possible, the researchers used radiocarbon dating data to separate areas that were heavily occupied from those that weren’t. The idea was that the scale of human activity at a particular site could be measured by how many organic samples could be found that were suitable for dating (more samples and more dates obtained meant more people had been living at a site during the time period in question).

When they compared their model to what the archaeological record showed, the researchers were thrilled to discover a strong correlation, which they believe establishes the validity of their approach.

"Our model shows that fear of conflict led to population declines in potentially dangerous areas,” CGS physicist and study lead author Daneil Kondor said in a CHS press release.

“As a result, people concentrated in safer locations, such as hilltops, where overpopulation could lead to higher mortality and lower fertility."

This dynamic would have inevitably led to an overall decline in the human population, regardless of whether or not a lot of people were killed during actual battles.

How the Fear of Conflict Shaped Ancient Societal Development

When fertility rates dropped and mortality rates rose in response to overcrowding and the increase in ill health this caused, the effects could have been reversed if people could have migrated to new places to start new settlements. But they would have been unable to do so if the threat of warfare and conflict was persistent, since their safety wouldn’t have been assured if they left the larger settlement to strike out on their own.

“We have many instances of temporal abandonment of open agricultural land, associated with a retreat of groups to well-defendable locations and considerable investments in large-scale defense systems like ramparts, palisades and ditches,” said study co-author Detlef Gronenborn, a German archaeologist from the Leibniz Center for Archaeology in Mainz.

From this point on, population densities would have remained at unhealthy levels and would have ultimately contributed to population crashes, just like those that Neolithic Europe actually experienced.

As renowned complexity scientist and research team member Peter Turchin points out, this pattern of reaction to the threat of conflict could have had ramifications for the structural development of society as a whole.

“This concentration of people in specific, often well-defended locations could have led to increasing wealth disparities and political structures that justified these differences,” he said. “In that way, indirect effects of conflict might have also played a crucial role in the emergence of larger political units and the rise of early states.”

This is exactly the type of big-picture conclusion that complexity science is noted for producing, which makes it a highly useful tool for archaeologists and historians seeking to understand the true significance of their discoveries.

Top image: Visualization of the situation around 3700 BC.                       Source: © Magistrat der Stadt Hofheim/ LEIZA, Architectura Virtualis  

By Nathan Falde