Elements of syntax in the systems of three language-trained animals
Which properties of syntax are uniquely human, and which can be acquired by other animals? Relevant evidence is provided by work with three language-trained animals: the African gray parrot Alex, who can produce and comprehend a small fragment of English; the bottle-nosed dolphins Ake and Phoenix, who can comprehend a gestural and an acoustic language, respectively; and the bonobo Kanzi, who can produce combinations of lexigrams and comprehend a significant fragment of English. The systems of these animals are examined for evidence of four core properties of syntax: discrete combinatorics, category-based rules, argument structure, and closed-class items. Additional studies that explore further what these animals can learn about these core properties are suggested.