Boundary Shedding as Basin Maintenance: A Control-Theoretic Extension of Life as a Phase Transition

Living systems persist by maintaining regulated states within bounded regions of state space under continuous perturbation. While prior work has defined life as a phase transition in regulation, less attention has been paid to the mechanisms required for such regulated basins to remain viable over time in open, dissipative environments. This paper argues that boundary shedding—the export of accumulated disorder, damage, or constraint—is a necessary control strategy for maintaining basin viability under sustained flow. Using a control-theoretic perspective, we show that if internal repair capacity is finite and boundary load production is non-zero, long-term persistence requires active export at the boundary. Shedding is therefore not an adaptive embellishment but a structural necessity imposed by regulation itself. The framework is scale-invariant and pre-genetic. Shedding arises wherever regulated boundaries exist, independent of genes, signalling, or multicellularity. Familiar biological processes such as vesicle release, cellular turnover, apoptosis, and sacrificial loss are reinterpreted as manifestations of basin maintenance rather than communication or failure. By situating shedding as a foundational requirement of regulated life, this work provides a mechanistic bridge between early chemical regulation and later biological complexity, and establishes a basis for understanding persistence, robustness, and controlled loss across scales. This paper is Companion Paper 3 in a series developing a regulation-first, boundary-centric framework for biological identity. Life as a Phase Transition — Series Overview Foundational framework A. An Architectural Origin of Organismal UnityFoundational Paperhttps://doi.org/10.5281/zenodo.18274230 B. Life as a Phase TransitionFoundational Paperhttps://doi.org/10.5281/zenodo.18176157→ Defines life as a maintained, non-equilibrium basin governed by regulation and boundary constraints. Heredity constraint and theory closure C. The Analogue Heredity Ceiling and the Basin Digitisation TransitionHeredity constraint frameworkhttps://doi.org/10.5281/zenodo.18250555→ Formalises the limit of compositional (analogue) heredity and explains why replayable archives (digitisation) become unavoidable within the life-as-a-phase-transition framework. Companion papers — Mechanisms and consequences 2. The Basin of Identity: microRNA as a Kinetic Anchor in Multicellular Dynamics https://doi.org/10.5281/zenodo.18181118 → Explores how kinetic anchoring mechanisms stabilise basin identity in multicellular systems, now interpretable as local management of identity dimensionality and heritability stress. 3.Boundary Shedding as Basin MaintenanceA Control-Theoretic Extension of Life as a Phase Transitionhttps://doi.org/10.5281/zenodo.18215113→ Describes boundary shedding as a regulatory strategy for maintaining basin coherence under stress. 4.Cohesive Membranes and the Emergence of Multicellular Basin IdentityWhen Many Compartments Become One Organismhttps://doi.org/10.5281/zenodo.18215283→ Examines how multicellular organisation emerges from coupled boundary systems and shared basin identity. 5. From Control to ReplayArchives, Development, and Sexual Reproduction in Boundary-Defined Lifehttps://doi.org/10.5281/zenodo.18215367→ Investigates replay, development, and sexual reproduction as stabilising mechanisms, now unified by the Basin Digitisation Transition. 6. Boundary Architecture and Failure in Living SystemsA regulation-first classification of biological formhttps://doi.org/10.5281/zenodo.18226987→ Classifies biological form and failure modes through boundary architecture and regulatory breakdown.