What Makes Human Language Uniquely Recursive?

Recursion has been claimed to be the only unique property of human language as in a bulk of Chomsky’s biolinguistic literature including the cross-species study in Hauser, Chomsky&Fitch (2002). The further question immediately ahead of us is what makes recursion a divide between human language and animal communications. To answer this question, in this thesis, we examine language from the sound side and we hypothesize that it is the availability of contrastive consonant (hereafter consonant) that marks the difference between human language and animal communication signals. The hypothetical logic is like this:given that discreteness is the prerequisite of recursion, and that human language would not be segmented into discrete elements for recursion without consonant, the availability of consonants in human language and the unavailability of consonants in animal communication signals would be the physical cause for the biolinguistics divide in terms of recursion.In this thesis, we define consonant emphasizing its contrastive property. Three pieces of existing evidence lend direct support to this hypothesis. One is that in child language acquisition, the presence of consonant makes infants capable of segmenting the speech stream into discrete elements before syntactic operations like Merge; the second one is that cotton-up tamarins cannot perceive consonants at all in the perception experiment in Newport et al.(2004); the third one comes from the theory of feature geometry in phonological study, in which [consonantal] is the root-node feature. Besides, more evidence is coming from our present study. We collect a number of samples of animal communication signals including those from mammals’ vocal production and birds’songs, and analyze them in Praat, finding that they are all holistic, and they exhibit no signs of what we define as consonants, thus resulting in their incapability of being decomposed into discrete elements.Evolutionarily, we agree with HCF that FLB (Faculty of language in broad sense) pre-exits FLN (Faculty of language in narrow sense)(e.g. Boeckx&Piattelli-Palmarini,2005), and we concur with many linguists that the emergence of human language faculty is an exaptation of three autonomous systems—narrow syntax, SM (sensory-motor) system and CI (conceptual-intentional) system (Fujita,2009). From the comparative perspective, it is acknowledged that non-human animals also have propositions, but without compositional property. It is the emergence of syntax (perhaps genetic mutation) that makes the holistic propositions compositional, which externalizes as discrete infinity of language (the property that Chomsky has repeatedly emphasized). Meanwhile, non-human animals have potentially owned phonological abilities (Samuels,2012), thus the externalization of sound is a process of mapping between the abstract morphosyntactic elements and phonetic forms, during which human beings are uniquely capable of doing so by mapping discrete infinity and discrete segments. Based on the Mutual Inclusive Algorithm proposed by Ning (2010), we propose that the production of consonants marks the emergence of human language faculty.If our hypothesis is proven to be on the right track, maybe to explore the genetic linkage to the perception and articulation of consonant can lead to a smaller scope (neural study or genetic study) than previous research to the study of genetic endowment for human language faculty.