Life’s hidden catalyst: the Boron Theorem and the chemistry of emergence

Life almost certainly began as chemistry long before the appearance of cells and genes. In this pre-cellular phase (Chemical Life), metastable reaction networks would have required mechanisms that increase the persistence of fragile intermediates, bias reaction pathways, and enable stepwise accumulation under non-equilibrium cycling. Here we propose that boron (B), through pH-dependent speciation and reversible interactions with polyhydroxylated substrates, can act as an effective chemical scaffold for ribonucleic acid (RNA)-relevant precursor chemistry. Under mildly alkaline and low water activity regimes (e.g., films, gels, evaporitic/brine microenvironments, and mineral interfaces), borate can reversibly associate with cis -diol motifs in sugars, favoring furanosyl forms (including ribose) and reducing degradative side reactions; in related settings, borate–sugar interactions can also help bias phosphate-transfer reactions toward improved regioselectivity. These roles address key constraints on prebiotic sugar persistence and phosphate availability/reactivity in bulk water. To operationalize when such effects are most plausible, we introduce the Boron Availability Index (BAI) as a heuristic, test-design metric integrating B speciation with environmental modifiers (water activity, ionic strength/competition, mineral buffering, and transport/exchange). We highlight an intermediate proposed test window (BAI ≈0.2–0.4, heuristic) where sugar stabilization, phosphorylation directionality, and network persistence can be jointly evaluated by controlled variation of physicochemical parameters. We therefore frame the Boron Theorem as a conditional, falsifiable constraint within RNA world-compatible pathways: environments that sustain B in a reactive, water-soluble form (borate) under suitable geochemical context are more likely to support Chemical Life by increasing the persistence and directional reactivity of ribose–phosphate intermediates.