This symposium aims to integrate different causal explanations into a coherent framework that will shed new light on the design features of natural communication systems. The program is organized according to four levels of analysis and explanation: Neural mechanisms, Ontogenetic processes, Adaptive significance, and Communication and cognitive processes to capture the causes underlying different communicative systems, and their evolutionary origins. Researchers working on a variety of sensory systems and animal groups will discuss their ideas and most recent findings. The symposium thus provides a unique forum for fostering interactions between scholars who typically attend different scientific meetings, and read different specialty journals. The end product will be more synthetic and comparative approach to understanding communication systems.