Abstract

Although language is arguably the hallmark of our species, its origin is one of the most intriguing issues of evolutionary biology. We have argued that speech, or vocal language, arose from a multimodal system of communication in our late ancestors in which vision and gestures, and voice and hearing were used to transmit different kinds of signals. How did these types of signals interact? Here we propose a neuronal mechanism for the generation of a multimodal system of communication, based on visual and motor contributions for speech perception through oscillatory coupling of the respective networks. These interactions may have been present in our early ancestors as well. Furthermore, these same kinds of processes may be involved in cross-talk between the language system and other multimodal networks involved in semantic processing, cognition and other functions, providing the contents of language and permeating language into multiple domains of our existence.