Language is a communication system. Human language is a particular example that is characterized by the use of a limited set of articulate sounds (phonemes) that can be combined in different ways to create meaningful units (morphemes and words). In turn, these meaningful units are combined into larger units (sentences). The relationship between different words in a sentence is provided by the grammar; grammar refers to the set of rules that govern the construction of phrases (syntax) and words (morphology) in a particular language. Consequently, any explanation about the origin of human language must consider the origins of phonology, vocabulary, and grammar. The characteristics of human phonological production are a direct result of the specific idiosyncrasies of the vocal tract, whereas vocabulary and grammar are ...