Fossil cues to the evolution of speech

Abstract

Abstract Speech (complex, articulated vocalization) is the default linguistic signaling mode for all human cultures, except for small populations (e.g. the deaf) for whom the audiomotor modality is unavailable. However, signed languages of the deaf are full, complex, grammatical languages, independent of, but equivalent in all important respects to, spoken languages (Stokoe 1960; Klima and Bellugi 1979), demonstrating that speech is not the only signaling system adequate to convey language. Therefore, a crucial distinction in language evolution is that which exists between speech (a signaling system) and language (a system for expressing thoughts, which can incorporate any one of several signaling systems). Additionally, speech can be decoupled from meaning, in certain circumstances, and be treated as a signal, pure and simple (other examples of complex articulated vocalization include infant babbling or jazz scat singing). And of course, additional and more ancient non-linguistic (non-propositional) communication via facial expression and ‘‘body language’’ is also found in all human populations. Nonetheless, speech remains the default linguistic signaling system for all unimpaired human cultures, and there is no evidence that this has ever been otherwise, until the advent of writing. Thus, the vast majority of linguistic constructions were conveyed via a speech signal during human evolution. Language evolution may well have been influenced or constrained by its reliance on the auditory/vocal modality.