Ten Seconds Into the Future. History.
Perhaps history is inevitably punctuated by crises. Life naturally grows until interrupted by environmental, social or political crises when the number of hosts, inhabitants or combatants is decimated, halting the crisis, and setting the stage for a potential but by no means guaranteed recovery.
There is an optimal population size below which collaboration leads to growth and beyond which tensions lead to fracture. The size of the habitat and the efficiency of communications are factors. For a given size of the physical habitat, communications allow both collaboration and competition. At the point when the dynamics of competition dominate that of collaboration, the population must migrate or expand into a greater space or face environmental, political or social crises.
Equilibria are characterised by balance. The trend following tendencies of humans leads to overshooting strategies approaching then exceeding points of balance. History therefore tends towards cycles. The further a system exceeds equilibrium, the more energy is accumulated for reversion to equilibrium.