Predator -- Prey

Lotka-Volterra dynamics / Beinhocker Ch 8 p.168

Endogenous Oscillations in Complex Adaptive Systems

The predator-prey system is one of the most fundamental examples of endogenous dynamics in complex systems. No external force drives the population cycles -- they arise purely from the internal logic of the interactions: prey reproduce, predators eat prey, predators starve when prey are scarce, prey rebound when predators decline.

Beinhocker uses Lotka-Volterra as a stepping stone toward the broader argument that economic systems are far-from-equilibrium -- they do not settle into a static optimum but continually oscillate, adapt, and restructure. The "invisible hand" is not a force toward equilibrium but a driver of perpetual motion through fitness landscapes.

Key Insight

The classic ODE model produces perfectly periodic orbits -- the system traces closed loops in phase space forever. But the agent-based spatial version introduces stochasticity, spatial heterogeneity, and the possibility of extinction. Small populations can vanish through random fluctuations even when the ODE predicts survival. This gap between the deterministic and stochastic views is central to Beinhocker's critique of traditional equilibrium economics.

Spatial Agent-Based
Classic ODE
Default
Prey Boom
Predator Heavy
Fast Starvation
Slow Breeding
Large World (100x100)
Tiny World (20x20)
Fragile Ecosystem
0
Tick
0
Prey (Rabbits)
0
Predators (Foxes)
100%
Grass Coverage
--
Est. Period

Spatial Grid

Grass
Prey
Predator
Bare

Population Over Time

Phase Space (Prey vs Predators)

Grass Coverage Over Time