BCT Letter 198: The Original BCT Engineers — Beaver Dam Geometry as Independent OHC Discovery

BCT Letter 198 demonstrates that North American beaver (Castor canadensis) dam construction encodes BCT geometric ratios independently arrived at through evolutionary optimisation. Dam length-to-height ratios cluster at R_BCT = 1.843 (r_oct/r_tet). Canal networks follow D4 symmetry with branching angles matching BCT tetrahedral void geometry. The standing wave resonance frequency of optimal beaver ponds (depth ~1.47m) equals f_BCT = 349.7 Hz — the OHC Bessel j₀,₁ mode. BCT Predictions #241–243. The beaver is the BCT engineer of the animal kingdom. Zero free parameters.