Persistence and loose coupling in living systems

In line with current efforts to achieve a general view of living systems the degree of coupling is considered using specific examples at the levels of cell and organ, organism and group, organization and society. Loose coupling among systems, similar to Ashby's concept of independence, contributes to stability by allowing persistent behavior of the system in the face of certain inputs. It can be achieved either actively, by having a more tightly coupled subsystem which compensates for a given category of input by negative feedback, or passively, by an arrangement which allows certain variables only limited access to the system. The evolution of adaptive and maladaptive degrees of coupling in different systems is discussed.