"Chaser has a way with words. She knows over a thousand of them--more than any other animal of any species except humans. In addition to common nouns like house, ball, and tree, she has memorized the names of more than one thousand toys and can retrieve any of them on command. Based on that learning, she and her owner and trainer, retired psychologist John Pilley, have moved on to further impressive feats, demonstrating her ability to understand sentences...