In experiments directed by her owner, psychologist John Pilley of Wofford College in Spartanburg, S.C., Chaser demonstrated her grasp of the basic elements of grammar by responding correctly to ...

She isn't the first animal to have a basic understanding of grammar. Studies published in the journal Cognition in 1984 indicated that dolphins can also grasp elements of grammar.

Grammar, on the other hand, really does render "right" and "wrong" judgments. "I spoke" is correct, "I speaked" is not. This isn't to say there aren't open or controversial questions of grammar.