Neurobiology of Syntax as the Core of Human Language

The human language capacity appears to be rooted in the ability to combine words into hierarchical structures making up phrases and sentences. There is substantial evidence that this ability is specific to humans. Other animals can use words or symbols to refer to objects and actions, and can even memorise sequences of syllables and symbols, but only humans create syntactic hierarchies to build up phrases and sentences. In humans syntactic rules and representations together with words constitute the basis of the language system which allows the construction of sentences that carry and convey meaning. The present article focuses on syntax as the hierarchy building component which is unique to humans and thought to be part of their neurobiological endowment (Friederici et al. 2017). This view was already formulated about 50 years ago by Erich Lenneberg (1967) in Biological Foundations of Language. He claimed that there must be an innate biological representation of the abstract structure of language in the human nervous system, and that language was characterised by “concatenations” which obey syntactic principles. Both claims have found supportive evidence in the past 50 years. While Lenneberg formulated his views mainly on the basis of behavioural language data from patients with brain lesions, today’s knowledge is based on data from functional brain imaging, measurements of the grey and white matter structures of the living brain as well the correlation of these with behavioural language measures.