What defines language and Language Faculty? based on Hauser, Chomsky & W Tecumseh, 2002

In continuation of my earlier post (dated 11 Nov, 2009) Is possessing a language a quintessentially human trait?


The boundary line between Human and non-human primates is characterized by language. Janes R Hurford in his article ‘Human Uniqueness, Learned Symbols and Recursive Thoughts’ says that equating language with communication is counterproductive. There are two features of human language that no other animal communication system involves: learned arbitrary symbols and recursive, semantically composed syntax. All words of any human language are symbolic. There is an arbitrary relationship between the signified concept and the signifier form. Human language also has semantically composed syntax. Words are put in different sequences to convey different messages and the messages are composed from the meanings of the words. However, some degree of syntactic patterning is also found in other primates in their communicative calls. But how they manipulate extremely long and complex signals is questionable.

Distinguishing the Shared and Unique Components of the Language Faculty (FLB & FLN)

In a recent research program, Hauser, Chomsky and Fitch are of the opinion that Language faculty can be divided into a broad (FLB) and narrow sense (FLN). FLB includes two components- sensory motor and conceptual intentional. FLN is the abstract linguistic computational system, independent of other systems with which it interacts and interfaces. The internal architecture of FLN is a computational system that generates infinite number of new sentences from a finite set of rules. A core property of FLN is recursion, often termed as discrete infinity. “This recursive mechanism entails a procedure that calls itself, specially combining the discrete store of words and sentence constituents into hierarchical phrase structures that can be further embedded with other hierarchically arranged phrase structures” (Tincoff & Hauser, to appear). Each expression of this mechanism is a pairing of sound and meaning and free from the restrictions, for instance, working memory, lung capacities etc. that often limits the FLB aspects. 

Comparative Methods

To discuss how these various components of language faculty have evolved, evolutionary biologists have suggested three methods:

1. Homologies: Traits which are not uniquely human evolved for an earlier function directly inherited from a common ancestor.
2. Homoplasies: A trait not uniquely human, shared by other species, but not present in their common ancestors, evolved for other purposes and was redesigned for language. FLB is derived, uniquely human adaptation for language.
3. A trait which is uniquely human, is a phylogenetically novel trait evolved only in human.

Evidence from homologous mechanism:

FLB is strictly homologous to animal communication. FLB is composed of the same functional elements that underlie communication in other species. Sensory motor system includes abilities used in vocal production, categorical perception and imitation which are also shared by other primates. On the side of vocal production, birds and non human primates naturally produce and perceive formants in their own species typical vocalization. Rich multimodal imitative capacities are seen in dolphins and birds, with most song birds exhibiting a well developed vocal imitative capacity. In a recent study, cotton tamarins have shown a perceptual mechanism for discriminating the rhythmic classes of spoken language. Conceptual intentional system includes conceptual representations (number, color spatial referents etc.). These abilities also to some extent shared by non human primates, only that they can not express it. What is strikingly different is the ability to form a lexicon. Even if they have it, the lexicon is small and no evidence is there for the capacity to generate novel strings. This is where, FLN comes, which is the only unique trait of human language.

FLN as defined by Hauser is especially the mechanism of recursion. Fitch & Hauser (2004) provide the most direct test of the FLN on the perceptual studies of some cotton top tamarins. The result shows that monkeys share with human the basic computational mechanism for finite state grammar. However, they fail to extract phrase structure grammar. In the experiment, tamarins were familiarized with a set of syllables following An Bn grammar. When they were tested with new strings, half violating the rule, half consistent with it, the tamarins failed to recognize the violations from the grammar consistent ones. This result shows that non human primates can not master hierarchically embedded structures.