Keywords: Aphasia, Executive Functions, Grammar, Language Evolution.
Grammar represents the most advanced element in human language. Language grammar
requires a lexicon as a departing condition. It is proposed that three stages of language
evolution can be distinguished: (a) Primitive communication systems using not only sounds
but also gestures, grunts, etc., similar to those observed in non-human primates; (b) initial
communication systems using a lexicon but without grammar; (c) complex communication
systems including language grammar. It is suggested that grammar originates from the
internal representation of actions resulting in the use of verbs; this ability depends on
the Broca’s area (left inferior frontal gyrus) and related brain areas. The development of
human language grammar is considered to be recent in human history. It is thought that
grammar was developed in two steps: (a) Proto-grammar: verb-noun compounds used for
naming; and (b) complex grammar, including diverse functional words. Finally, it is suggested
that grammar represents the origin of complex cognition (“executive functionsµ).