How could language have evolved?

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}.

Figure 1. The binary operation of merge (X,Y) when Y is a subset of X leads to the ubiquitous phenomenon of “displacement” in human language, as in Guess what boys eat.

Left: The circled structure Y, corresponding to what, the object of the verb eat, is a subset of the circled structure X, corresponding to boys eat what. Right: The free application of merge to X, Y in this case automatically leads to what occupying two syntactic positions, as required for proper semantic interpretation. The original what remains as the object of the verb so that it can serve as an argument to this predicate, and a copy of what, “displaced,” is now in the position of a quantificational operator so that the form can be interpreted as “for what x, boys eat x.” Typically, only the higher what is actually pronounced, as indicated by the line drawn through the lower what.

Figure 2. A crude plot of average hominid brain sizes over time.

Although after an initial flatlining this plot appears to show consistent enlargement of hominid brains over the last 2 million years, it is essential to note that these brain volumes are averaged across a number of independent lineages within the genus Homo and likely represent the preferential success of larger-brained species. From . Image credit: Gisselle Garcia, artist (brain images).