For over half a century, innovative scientists have tested the abilities of animals to learn to communicate using human systems, such as American Sign Language with chimps and gorillas. One could go back even farther in time, to the start of the 20th century, when the German mathematics teacher Wilhelm von Osten trained his Russian trotting horse Hans to answer questions, do simple math, and discriminate consonant vs. dissonant musical chords, all by nodding his head, tapping a hoof, pointing his nose, or picking up objects in his mouth. More recently, one of the most remarkable of such animal communication programs is that run by Irene Pepperberg. Irene has spent the past four decades teaching African grey parrots to talk – and not just to talk, but also to answer complex questions about the nature and number of objects. Irene's purpose is to test the limits of communication between humans and animals. Irene is the author of many articles and several books, including the New York Times best-seller "Alex & me. How a scientist and a parrot discovered a hidden world of animal intelligence – and formed a deep bond in the process".