We teach differential calculus and how to tie shoes. We teach biochemistry and computer science, carpentry and pottery. When I was in middle school, I took an after-school calligraphy class. I spent two seasons trying football, one season attempting basketball, and one learning volleyball. I took drawing classes and painting classes, and spent one long afternoon learning the art of flower arrangement. In school, I enrolled in a badminton elective. I spent two years trying to learn to play the guitar.
What is it about humans that allows us to teach in a way that no other animal does? Gergely and Csibra argue that human communication itself is special. They write, "If I point at two aeroplanes and tell you that ‘aeroplanes fly’, what you learn is not restricted to the particular aeroplanes you see or to the present context, but will provide you generic knowledge about the kind of artifact these planes belong to that is generalisable to other members of the category and to variable contexts…"
What they're saying is that the generalisability of the information is manifest within the communication itself. They continue, "If I show you by manual demonstration how to open a milk carton, what you will learn is how to open that kind of container," not how to open only that particular container. The transmission of general knowledge is implicit within human communication, whether that communication is linguistic or not, it doesn't need to be deduced or inferred by the learner.
Of all the animals in the world, only humans build skyscrapers, follow recipes, play backgammon, learn statistics, receive DVDs by mail, and place laser-wielding robots on Mars. The kind of culture that humans enjoy can only exist because we are so proficient at teaching and at learning from teachers. In most ways, the differences between humans and non-human animals are ones of degree rather than of kind. But there’s one categorical difference between our species and every other. We teach, and we teach anything.