Many of us like to think our dogs are smart, as we point to their ability to read our facial expressions and understand what we say. But some dogs are exceptional. Take Chaser, an American border collie dubbed the “smartest dog in the world,” who could recognize and remember 1,022 nouns—one for each of her toys.In Germany, another border collie, a male named Rico, practiced “fast-mapping,” or figuring out the names of new things with the speed and acumen of a three-year-old child. A handful of other border collies—as well as two Yorkshire terriers, one from Brazil named Vicky Nina, the other an American pooch, Bailey—have been found to be similarly talented.