The ratchet effect is responsible for all complexity: once a stable state is established with a set of constraints, it cannot go back to the preexisting state, but only toward a new set of constrained states. The new state is said to be irreversible. This is how increased complexity within a system is achieved.
Said another way: once a threshold is crossed, you cannot go back, because a new stable state equilibrium is established, and resistant to disequilibrium, or entropy. This is due to a kind of crystallization.
You can visualize a cascade of sorts. Thermodynamic energy vibrates particles into a state that is more stable, and irreversible. Only a more complex state can be reached.
This seems to occur with knowledge acquisition in general. You cannot “un-know” something.
In genetic evolution, I imagine this is precisely how DNA assembles, and increases complexity.
Homeodynamics (thermodymaics) -> morphodynamics (self-organization) -> teleodynamics (life)