Landscape of Fear: Indirect effects of conflict can account for large-scale population declines in non-state societies

Why do the 99.9% of humanity live in large-scale societies organized as states? During the Holocene (the last 10,000 years), human societies have been transformed utterly: from small groups of nomadic foragers to our current interconnected world of large-scale societies organized as states. Population numbers, agricultural productivity, technological…

What was history's biggest empire? Or the tallest building of the ancient world? What was the plumbing like in medieval Byzantium? The average wage in the Mughal Empire? Where did scientific writing first emerge? What was the bloodiest ever ritual human sacrifice? We are used to thinking about history in terms of stories. Yet we understand our own world…

We organize ourselves into communities of hundreds of millions of individuals, inhabit every continent, and send people into space. Human beings are nature’s greatest team players. And the truly astounding thing is, we only started our steep climb to the top of the rankings—overtaking wasps, bees, termites and ants—in the last 10,000 years. Genetic…

In War and Peace and War, Peter Turchin uses his expertise in evolutionary biology to offer a bold new theory about the course of world history. Turchin argues that the key to the formation of an empire is a society’s capacity for collective action. He demonstrates that high levels of cooperation are found where people have to band together to fight off…

The impact of inter-group conflict on population dynamics has long been debated, especially for prehistoric and non-state societies. In this work, we consider that beyond direct battle casualties, conflicts can also create a ‘landscape of fear’ in which many non-combatants near theatres 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 applying analytical and computational modelling, we demonstrate that these indirect effects of conflict are sufficient to produce substantial, long-term population boom-and-bust patterns in non-state societies, such as the case of Mid-Holocene Europe. We also demonstrate that greater availability of defensible locations act to protect and maintain the supply of combatants, increasing the permanence of the landscape of fear and the likelihood of endemic warfare.

Why did complex societies, characterized by densely-populated walled cities, first arise in northern China, jump-starting early Chinese civilization? We explore this question in three steps. First, the North, especially the alluvial plains along the Yellow and the Yangtze Rivers, had generally flatter terrains than the South. Second, by dividing China’s landmass into 100 km ×100 km grid-cells and using our archaeological database, we demonstrate that cells with flatter terrains faced higher war threats in prehistoric and early historic times, where war threats are respectively proxied by each cell’s number of excavated military grave goods for the Neolithic period (8000−1700 BCE) and by its number of recorded conflicts for the Eastern Zhou (770−221 BCE, the earliest period for which war data are available). Third, we establish that during both the Neolithic and the Eastern Zhou, higher war threats led to the construction of more settlements with defensive walls and moats, resulting in more walled cities (i.e., early cradles of civilization). Thus, warfare was a key driver of the evolution of complex societies. This finding is robust after controlling for irrigation potential, agricultural productivity, and threats from the steppe, as well as under alternative specifications.