The Five Finger Proof: Universal Tetrapod Pentadactyly as the First Confirmed Case of Attractor Geometry Displacement as Sole Causal Mechanism for a Universal Morphological Program, and the Derivation That Novel Organisms Can Be Constructed Through Reproductive Intervention Without Survival Pressure

We present a geometric derivation of the causal mechanism for universal tetrapod pentadactyly, arriving at attractor geometry displacement by ultraviolet-B (UV-B) radiation at D≈0 of the HoxD limb developmental program as the confirmed sole causal mechanism. Six discriminating conditions that distinguish attractor geometry displacement from survival-pressure-driven selection are applied to the pentadactyly case. All six are confirmed by published literature. The survival-pressure mechanism fails all four of its own predicted signatures. The primary evidence base is Marshall et al. 2020 (Science Advances eaba0768), which confirmed UV-B as the kill mechanism at the Devonian-Carboniferous boundary (~359 Ma) via malformed spore DNA damage visible before protective wall formation, combined with the published record of Devonian polydactyly, published HoxD digit specification developmental biology, and published UV-induced HoxD disruption studies in proxy species. These four published data sets have not been previously connected. Their connection constitutes a new causal mechanism statement for the origin of universal tetrapod pentadactyly. Romer's Gap (360-345 Ma) is derived as the attractor stabilisation period. The ARM D experimental protocol is derived as the deliberate laboratory replication of the same mechanism at the LECA base state (D=0). Novel organisms can be constructed through this mechanism without survival pressure. The derivation originated from attractor geometry applied to cancer drug targets. Timestamp: 2026-03-13.