New in paperback. Hardcover was published in 2012. Everett argues that, like other tools, language was invented by humans and can be reinvented or lost. He shows how the evolution of different language forms - that is, different grammar - reflects how language is influenced by human societies and experiences, and how it expresses their great variety. Combining anthropology, primatology, computer science, philosophy, linguistics, psychology, and his own pioneering - and adventurous - research with the Amazonian Pirahã, and using insights from many different languages and cultures, Everett gives us an unprecedented elucidation of this society-defined nature of language. In doing so, he also gives us a new understanding of how we think and who we are.