How Could Language Have Evolved? by Johan J. Bolhuis, Ian Tattersall, Noam Chomsky, Robert C. Berwick.
Abstract:
The evolution of the faculty of language largely remains an enigma. In this essay, we ask why. Language’s evolutionary analysis is complicated because it has no equivalent in any nonhuman species. There is also no consensus regarding the essential nature of the language “phenotype.” According to the “Strong Minimalist Thesis,” the key distinguishing feature of language (and what evolutionary theory must explain) is hierarchical syntactic structure. The faculty of language is likely to have emerged quite recently in evolutionary terms, some 70,000–100,000 years ago, and does not seem to have undergone modification since then, though individual languages do of course change over time, operating within this basic framework. The recent emergence of language and its stability are both consistent with the Strong Minimalist Thesis, which has at its core a single repeatable operation that takes exactly two syntactic elements a and b and assembles them to form the set {a, b}.
Interesting that Chomsky and his co-authors have seized upon “hierarchical syntactic structure” as “the key distinguishing feature of language.”
Remember text as an Ordered Hierarchy of Content Objects (OHCO), which has made the rounds in markup circles since 1993. It’s staying power was quite surprising since examples are hard to find outside of markup text encodings. Your average text prior to markup can be mapped to OHCO only with difficulty in most cases.
Syntactic structures are attributed to languages so be mindful that any “hierarchical syntactic structure” is entirely of human origin separate and apart from language.