This chapter deals with the cultural evolution of the ability to organize words in meaningful grammatical sequences. The argument is that syntactic skill evolved because it was necessary for communicating about perceptually absent (past, future, hidden, or possible) events that are or can be represented in the nonverbal imagery system, thereby enhancing the communicative usefulness of language in constantly changing contexts. This view contrasts with abstract computational theories of grammar that are designed to generate an infinite number of grammatical sentences using combinatorial rules that operate recursively on a set of linguistic symbols. Such grammars formalize the reflexivity design feature of language, that is, they use language rules to operate on language itself. This intriguing language game is limited as a model of real language because it does not include the situational uncertainties of language use. In this regard, formal grammars share the explanatory limitations of all formalisms as discussed in earlier chapters. Natural-language syntax is free of such constraints because it is driven by meaning and pragmatic demands. Such a system evolved in ways that can be described by DCT.