Signalling is one of the defining achievements of living organisation, but it is not the origin of biological agency.
It is tempting to suppose that increasingly sophisticated communication systems create agency. Plants coordinate activity through electrical, hydraulic, chemical, and mechanical signals, while animals rely heavily upon nervous systems. Because signalling enables coordinated behaviour, it is sometimes treated as the feature from which agency emerges.
APS reverses this explanatory relationship.
Living systems require signalling because they are already biological agents engaged in maintaining their own viability. As organisms become more complex, coordination across cells, tissues, and organs becomes increasingly important. Signalling systems evolve because they improve the regulation of organised persistence, not because they create the capacity for agency itself.
This distinction explains why very different organisms possess very different signalling mechanisms while exhibiting the same underlying biological property. Plants, animals, fungi, and microorganisms communicate through different physiological processes, yet all must continually coordinate activity in ways that sustain viable organisation. What differs is the mechanism of signalling; what remains constant is the viability-oriented agency that those mechanisms serve.
APS therefore treats signalling as an organisational instrument of agency rather than its source. Communication enables living systems to regulate themselves more effectively, but the biological necessity for regulation exists before any particular signalling system evolves.
APS Principle: Signalling coordinates biological agency. It does not create it.