Differentiation between agents and patients in the putative two-word stage of language evolution

Several scholars have proposed that there was a two-word stage in the course of language evolution, in which utterances could not combine more than two words. These models agree that the putative two-word stage did not exhibit syntax. However, they disagree on whether or not there existed rules for inferring the semantic relationship between the two words expressing a compositional proposition. Focusing on semantically transitive events, I combine in the present paper language evolution models with previous empirical studies in linguistics to argue that the two-word stage was indeed governed by rules for inferring the compositional meaning of the utterance, in that (1) words were either associated with fixed (“predetermined”) semantic roles (i.e., agent, patient, predicate) or (2) there was a fixed order of semantic roles and the same words could be assigned different semantic roles in different utterances. Given the proposed existence of rules for producing and interpreting semantically compositional messages, it would appear that the putative two-word stage of language evolution did in fact exhibit syntax.