Social complexity and collapse

With the tools of complexity science and data from the past we begin to understand social systems with the precision we know from natural sciences.

Our main research questions

The evolution of complex societies:

What explains the dramatic increase in the scale and complexity of human societies over the past 10,000 years?

The resilience and fragility of complex societies:

Why do all complex state-level societies experience periodic social stress, often leading to state breakdown and sometimes to social collapse?

Surviving social crisis:

Why do some societies emerge from periods of crisis relatively unscathed, while others suffer mass bloodshed, population crashes, and institutional loss?

Are there laws behind the ways people organize in groups and the ways societies rise and fall?

To what extent are human societies predictable?

Old questions, new toolbox


Understanding complexity and collapse with Big Data and computational models



Over the past 10,000 years, human societies have evolved from small-scale egalitarian groups to complex, large-scale societies characterized by great differentials in wealth and power, extensive division of labor, and elaborate governance structures. There are many theories attempting to explain this major evolutionary transition. Which are correct?


Another challenge for researchers is that social complexity has not increased in a steady, gradual fashion. Instead, complex human societies—including our own—periodically experience social dysfunction and turbulence, which often results in state breakdown, political fragmentation, simplification of the economy, population declines, and loss of institutions and other accumulated cultural knowledge. Again, past thinkers and modern social scientists have put forward myriad theories explaining social collapse, but these theories have not yet been systematically tested with massive amounts of data.

CSH scientists dealing with Social Complexity & Collapse:

Peter Turchin

Team Leader
“Social Complexity and Collapse”

Jenny Reddish

Majid Benam

Dániel Kondor

Seshat: Global History Database 


Peter Turchin’s team at the Hub is using a massive accumulation of empirical historical data—the Seshat: Global History Database—to test theoretical predictions about the evolution of social complexity and the causes of collapse. We translate various theories, proposed to explain social complexity and collapse, into mathematical models, and build large databases to empirically test model predictions. For example, we quantify the importance of various structural pressures underlying societal breakdown: popular immiseration, growing inequality, intra-elite competition and conflict, state fiscal distress, unraveling of social norms, external military pressure, and environmental factors such as droughts and pandemics. Our aim is to merge the computational and statistical methods of complexity science with the new discipline of Cultural Evolution and more traditional theories in social sciences, while fully deploying data on past societies from history and archaeology.

Stefan Thurner

Team Leader

Tuan Minh Pham