It won't surprise most dog owners, but now scientists know it: The average dog is as smart as a 2-year-old child, reports the Telegraph. Dogs understand up to 250 words and gestures, can count to 5, and do basic calculations, researchers have found. "Obviously, you can't have a conversation with a dog"—at least not a two-way conversation—but dogs are among the most intelligent animals, and rival apes and parrots in language comprehension, says researcher Stanley Coren.
Border collies and retrievers were the breeds that scored the highest on tests usually used to measure young human abilities. Something else owners of "bad dogs" know: Their tail-wagging pets can "deliberately deceive—which is something that young children only start developing later in their life," said Coren.