We study how functional constraints bound and shape evolution through an analysis of mammalian voltage-gated sodium channels. The primary function of sodium channels is to allow the propagation of action potentials. Since Hodgkin and Huxley. mathematical models have suggested that sodium channel properties need to be tightly constrained for an action potential to propagate. https://www.roneverhart.com/Jaakaapin-raikastin-Fummom-InnovaGoods/