We humans are the only animals that learn and use language naturally. Why is that? Is it a matter of genetics? Brain size? Culture? Is it really just a matter of how we define 'language'? We will look at the past several decades of experimental evidence on attempts to teach non-human primates such as chimpanzees, gorillas, orangutans to learn and use something like human languages, as well as examine naturally-occurring primate and animal communication systems. We will address a wide of cognitive, evolutionary and other biological issues that bear on these matters. The course will focus primarily on non-human primates, but also include parrots, bees, and more.