Globalization, migration, climate change and war—nation states are currently under huge pressure on many fronts. Understanding the forces that initially drove the emergence of states across the world may help explain why.

For a long time after humans evolved, we lived in oral-based, mostly small-scale and egalitarian societies. Things began to change with the dawn of the Holocene, when a suite of climatic, social and technological shifts led to the emergence of the first states about 5,000 years ago.

The earliest known state was in Mesopotamia (now southern Iraq), followed by Egypt, the Indus Valley, China and Meso-America. The long-standing view was that the invention of agriculture was the spur for these large-scale human societies to emerge. But there was a 4,000-year gap between the expansion of agriculture (circa 9,000 years ago) and the founding of the earliest states, which throws this link into question.