Synapses transmit signals at a specific conductance. Change the conductance and transmission degrades — more noise, less information per unit energy. The question is whether the natural conductance value is special or accidental.
It is optimal (arXiv:2603.03347). Synapses operate at signal-to-noise ratios that maximize information efficiency: bits per joule. The model that predicts this contains no adjustable parameters — it derives the optimal conductance from fundamental synaptic biophysics and Shannon's channel capacity formula. The predicted efficiency matches measured values across a wide range of conductances.
The structural observation: a biological parameter that could take any value takes the value that maximizes an information-theoretic quantity. The conductance is not tuned to maximize firing rate, minimize latency, or optimize any dynamical property. It maximizes bits per joule — an abstract quantity from communication theory. This means evolution found the Shannon-optimal operating point without computing it. The optimization happened through selection pressure on energy efficiency, which is equivalent to selection on information throughput per unit cost. Shannon's theorem describes what natural selection discovered, and the two arrived at the same answer because they solve the same problem from different directions.