Biological evolution is commonly described as a process driven by variation, selection, and inheritance. However, evolutionary outcomes are constrained by structural, energetic, and environmental limitations that restrict which adaptations are viable. This paper interprets evolutionary adaptation within the Paton System framework as a process governed by admissibility conditions. Evolutionary change is possible only when new biological configurations remain compatible with the structural constraints of the organism and its environment. Mutations or developmental pathways that violate these constraints cannot persist and are removed from the evolutionary trajectory of the system. Evolutionary constraint compatibility therefore defines the admissible region within which biological adaptation can occur. Biological organisms operate under constraints including metabolic limits, developmental pathways, genetic compatibility, ecological relationships, and environmental resource availability. These factors define the structural envelope within which biological systems can persist. Evolution therefore proceeds through variations that remain compatible with these constraints rather than exploring unrestricted biological possibilities. Under environmental strain, biological systems may compress toward minimal viable configurations in order to maintain persistence. Within the Paton System this behaviour corresponds to movement toward the Lowest Admissible Configuration (LCD) under constraint pressure. By interpreting evolutionary processes through admissibility boundaries, the Paton System provides a structural explanation for the persistence of certain biological adaptations, the recurrence of convergent evolution, and the collapse or extinction of organisms that violate evolutionary constraint compatibility.
Andrew John Paton (2026) studied this question.