A number of interactions including ecological,
social, and economical ones are more complicated than those
of spins in that they are usually asymmetric and history dependent.
For this reason, most of these systems beyond the simple
physics model cannot be described by the simple Hamiltonian
approach. Even if no analytical solution is available,
we can expect the system to evolve by successive local adaptations,
searching for an optimal point on the fitness landscape.
However, the equilibrium reached by local dynamics may
not be optimal in a global sense.