Constraint Geometry in Natural Product Biosynthesis

Natural product biosynthesis is often framed through the lenses of enzymatic novelty, pathway diversity, and evolutionary contingency. Yet across systems, a deeper, more profound regularity emerges, biosynthetic space is shaped not only by genetic potential but by the geometric constraints imposed by ecological context, metabolic flux, and structural feasibility. This perspective outlines a minimal conceptual framework for understanding how constraint geometry governs the emergence, stability, and diversification of natural product families. Rather than proposing new theory, it synthesizes existing observations into a coherent lens that highlights why certain scaffolds recur, why others remain rare, and how ecological pressures delimit the accessible chemical landscape. The aim of this paper is to provide a compact, integrative reference point for researchers seeking to understand the deeper architecture underlying biosynthetic outcomes.