Can the integration hypothesis account for language evolution?

•This paper argues against the Integration Hypothesis proposed by Shigeru Miyagawa and colleagues in recent articles.•The hypothesis suggests an 'emergent' view of language evolution: two primitive systems were integrated abruptly to form language.•The proposed systems are 'Expressive', occurring in birdsong, and 'Lexical', said to originate in monkey alarm calls.

In a recent series of papers, Shigeru Miyagawa and colleagues propose an Integration Hypothesis for language evolution (Miyagawa, 2016; Miyagawa, Ojima, Berwick, & Okanoya, 2014, 2013; Nóbrega & Miyagawa, 2015). This model suggests an 'emergent' view of language evolution in which two primitive systems, both occurring in animal communication, were integrated abruptly in our recent ancestors to form language as we know it. The proposed pre-existing systems are an 'E' system, for 'expressive', which occurs in learned birdsong, and an 'L' system, for 'lexical', which is said to have its origins in monkey alarm calls. What is distinctive about our hominin ancestors is that they alone attained the ability to 'merge' signals, so forming both words and syntax immediately via the integration of the L-system and the E-system. This view thus differs from much current work on the evolution of language, which suggests the gradual development of syntactic language from a pre-linguistic protolanguage. Here, I argue against the Integration Hypothesis, proposing that the two putative systems in animal communication do not have the requisite properties to form the basis for language. Conversely, the gradualist view of language evolution is well able to explain how grammatical and functional elements in language develop, uniquely in humans.