Meaningful syntactic structure in songbird vocalizations?

The faculty of language is thought to be uniquely human.Recently, it has been claimed that songbirds are able to associate meaning with sound, comparable to the way that humans do.In human language, the meaning of expressions (semantics) is dependent on a mindinternal hierarchical structure (syntax).Meaning is associated with structure through the principle of compositionality, whereby the meaning of a complex expression is a function of the meaning of its constituent parts and the mode of composition.We argue that while recent experimental findings on songbird call sequences offer exciting novel insights into animal communication, despite claims to the contrary, they are quite unlike what we find in human language.There are indeed remarkable behavioral and neural parallels in auditoryvocal imitation learning between songbirds and human infants that are absent in our closest evolutionary relatives, the great apes.But so far, there is no convincing evidence of syntaxdetermined meaning in nonhuman animals.Birdsong has become a prominent animal model system for investigating the evolution and mechanisms of human speech and language.This is mainly due to some remarkable behavioral and neural parallels between the acquisition of spoken language (speech) in human infants and song learning in juvenile songbirds [1,2] that are absent in our closest relatives, the great apes.Three recent studies [3-5] claim to have found clear evidence that songbirds-the Japanese tit (Parus minor) and the southern pied babbler (Turdoides bicolor)-possess a humanlike ability to syntactically combine vocalizations to create more complex meanings.In other words, these animals are suggested to possess a sound-structure-meaning mapping similar to human language competence.Such results are extremely interesting, illustrating how comparative biological research might shed light on what is uniquely human to language, as well as gaining insight on the evolution of speech and language [6].However, these results also demonstrate the difficulties involved in investigating "syntax" in nonhuman animals.