Is possessing a language a quintessentially human trait? Few more readings & views....

For the past 40 years, biologists, psychologists and anthropologists have been chasing Chomsky’s claim of Language as human uniqueness by looking at the capacities of animals to acquire some form of a human natural language under intensive training environments, or for animals to use their natural, species-typical vocalizations in ways that are similar to spoken language. Thus, for example, studies have focused on the capacity of human-reared apes to string symbols together to form sentences or comprehend them and of wild monkey populations to use vocalizations to refer to objects and events in the external environment. Though these studies have met with mixed success, especially as viewed from the perspective of linguists looking at such comparative data for insights into the evolution of language (the calls of these primates show some degree of learnability and of voluntary control), the minimal language of the great apes differs radically from human language.

In their article ‘The Faculty of Language: What is it, who has it and how did it evolve?’

Hauser, Chomsky and Fitch (HCF) explore the problem of language evolution in the line of distinguishing language as a communicative system and language as a system concerning abstract computational mechanism. The debate between human language and animal communication is discussed in the light of three parameters: (i) shared vs. unique characteristics of language and animal communication. Although bees dance, birds and whales sing, chimps grunt and scream, they differ from human language since they lack the expressiveness and recursive abilities of human language. 

(ii) Did language evolve gradually or through some qualitative shift? and finally,

(iii) continuity vs. exaptation (whether language evolved by gradual extension of pre-existing communication system or whether important aspects of language have been exapted away from their previous adaptive functions). The article examines the question of what is special about language, which aspects of language inherited from our ancestors have remained unchanged, what has been subjected to modifications and what is qualitatively new. HCF differentiates between two aspects of language that are special, the ‘narrow language faculty (FLN)’ and ‘the faculty of language in its entirety, the broad language faculty (FLB)’. They make the extraordinary proposal that FLN only includes recursion and the only uniquely human component of the faculty of language. 

‘Rule Learning by Cotton top Tamarins’ by Hauser, Weiss and Marcus examines whether the ability of rapid generalizing patterns of human infants is uniquely human. To address this problem they have presented the results of an experiment done on tamarins using a familiarization/discrimination method, which showed that tamarins were able to distinguish between novel strings of two different structures- one familiar and the other unfamiliar. This means tamarins are capable of recognizing abstract relations between variables and rules. Then, why can’t they learn language? In reply to this, the authors are of the opinion that ability to language is more than abstracting relations or patterns; it also depends on maintaining a lexicon, the ability to form semantic representation and to link them with syntactic configurations and the ability to represent hierarchical structure. Moreover, there is no evidence to date that monkeys have a theory of mind, which is crucial to language learning.

In ‘Computational Constraints on Syntactic Processing in nonhuman Primates’, Hauser & Fitch say that monkeys are unable to master phrase structure grammar. In their experiment, given exposure to instances of the patterns ABAB and ABABAB, tamarin monkeys showed increased interest in patterns AABB and AAABBB, perhaps because these contained two to four copies of the salient (because repeated) two-element sequences  AA and BB, which they had not heard before. By contrast, given exposure to instances of the patterns AABB and AAABBB, other tamarins did not show significantly increased interest in the patterns ABAB and ABABAB, perhaps because it does not involve a repetition. Given the same stimulus sequences, human subjects were able to categorize the new patterns as different, regardless of the direction of training and testing. The results of the experiment suggests that despite a clear ability to process sequential regularities in acoustics strings, tamarins are unable to process a simple phrase structure, where components of one portion of a string are related to other components some distance away. The article poses the necessity of future work on the computational limitations of non human primates in general.
More to follow...