ABSTRACT
Most of us view ion channels through the lens of human physiology, frequently focusing on the roles they play in neuronal signaling and muscle contraction. But ion channels are contributors to virtually every physiological response, and the amazing functional and molecular diversity of animal ion channels described in this volume reflects this constant presence. To fully understand the origins of our ion channels and the relationships between them, we need expand our horizons beyond human physiology and look much further back in evolutionary time. Ion channels indeed appear to be required for cellular life and are found in all cellular organisms from bacteria to plants to humans. Much of the diversity of channels central to animal physiology is built upon an ancient foundation of ion channel structures inherited from our early eukaryotic and even prokaryotic ancestors. The animal ion channel classes described in this volume have therefore been diversifying over vast evolutionary time scales, hundreds of millions to billions of years.
