ABSTRACT
Despite all of the different modalities used for communication by animals on Earth – visual, acoustic, olfactory, etc. – only one instance of language has arisen in almost four billion years of evolution. Can we draw any conclusions from this single observation about the communicative medium that would be used for language on other planets? I discuss the particular advantages (and disadvantages) of the two most widely used and richest communication channels on this planet – the acoustic and visual modalities – and examine what constraints would favour or disfavour their use on another planet as the basis for linguistic communication. Animals on Earth have exploited almost every possible physical modality for communication (bar one: magnetic signals), and the ecological constraints on each of these – range, speed, diffraction, and, crucially, bandwidth – are also physical constraints that would be likely to apply on alien planets, as well. Questions of information encoding also arise: Is it possible to construct a language out of binary (north/south) magnetic signals? Or graded signals so widely used across non-human animals? Perhaps the most important factor driving the evolution of an acoustic language in humans has been the fact that sound was only a secondary sensory medium for our ancestors, leaving sufficient bandwidth for communicative information without interfering with the necessity for sensing their surrounds, primarily carried out using vision. Such considerations of evolutionary, ecological, and physical constraints are likely to shape the evolution of language on other planets, just as they have done on our own.
