Our language is more unique than rare in the animal world. Like so many aspects of our behavior, we can best understand how it evolved by looking at how other species – more or less like us – communicate. Our language is not only spoken, but we often use gestures to understand each other. Just think of how much we gesture on the phone when the other person cannot even see us! We know that even great apes communicate with each other using gestures. But how similar are they to ours? How well could we understand what they are saying to each other?