Interweaving protosign and protospeech: Further developments beyond the mirror

We distinguish “language readiness” (biological) from “having language” (cultural) and outline a hypothesis for the evolution of the language-ready brain and language involving seven stages: S1: grasping; S2: a mirror system for grasping; S3: a simple imitation system for grasping, shared with the common ancestor of human and chimpanzee; S4: a complex imitation system for grasping; S5: protosign, breaking through the fixed repertoire of primate vocalizations to yield an open repertoire for communication; S6: protospeech, the open-ended production and perception of sequences of vocal gestures, without these sequences constituting a full language; and S7: a process of cultural evolution in Homo sapiens yielding full human languages. The present paper will examine the subhypothesis that protosign (S5) formed a scaffolding for protospeech (S6), but that the two interacted with each other in supporting the evolution of brain and body that made Homo sapiens “language-ready”.