Angela D. Friederici, Jörg Bahlmann, Stefan Heim, Ricarda I. Schubotz, Alfred Anwander. The brain differentiates human and non-human grammars: Functional localization and structural connectivity. PNAS, Early Edition, February 6, 2006
By a simple linguistic task is meant that one can comprehend the probability that a certain word, e.g. an article, comes before another word, e.g. a substantive or a verb. For example it is much more likely to find an expression such as "a book" than one like "an eat". Such a rule can also be understood by primates.
On the other hand a complex linguistic structure, such as a sentence, involves a more complicated hierarchical composition of words. For example to understand a sentence such as "I take the bus from A to B" one is required to organize the words in more complex relationships.
Researchers have now found that this task is done by a different area of the brain, the Broca's Area, which appeared later in the development of the brain.
The non-human primates' inability to deal with complex hierarchical linguistic structures had been previously demonstrated by behavioral tests. Angela D. Friederici and her colleagues from the Max Plank Institute for Human Cognitive and Brain Sciences wanted to get a grip on the neuronal basis of the difference.