As Turchin et al. developed cliodynamics, they found that two trends dominate the data on political instability:
The first, which they call the secular cycle, extends over two to three centuries. It starts with a relatively egalitarian society, in which supply and demand for labour roughly balance out. In time, the population grows, labour supply outstrips demand, elites form and the living standards of the poorest fall. At a certain point, the society becomes top-heavy with elites, who start fighting for power. Political instability ensues and leads to collapse, and the cycle begins again.
Superimposed on that secular trend, the researchers observe a shorter cycle that spans 50 years — roughly two generations. Turchin calls this the fathers-and-sons cycle: the father responds violently to a perceived social injustice; the son lives with the miserable legacy of the resulting conflict and abstains; the third generation begins again. Turchin likens this cycle to a forest fire that ignites and burns out, until a sufficient amount of underbrush accumulates and the cycle recommences.
These two interacting cycles, he says, fit patterns of instability across Europe and Asia from the fifth century BC onwards. Together, they describe the bumpy transition of the Roman Republic to the Roman Empire in the first century BC. He sees the same patterns in ancient Egypt, China and Russia, and says that they explain the timing of last year’s Egyptian uprising, which took the regime of then-president Hosni Mubarak by surprise. At the time, the Egyptian economy was growing and poverty levels were among the lowest in the developing world, so the regime could reasonably have expected stability. In the decade leading up to the revolution, however, the country saw a quadrupling of graduates with no prospects — a marker of elite overproduction and hence, Turchin argues, trouble.