In the ongoing debate about evolution, scholars frequently argue either the perspective that humans stand as the end product of a deliberate process or that they derive from a series of random acts of natural selection. David F. Armstrong’s new book Original Signs embraces the Darwinian concept of natural selection and extends it to apply to the formation of language. While most current linguistic theory envisions language as a system for translating the contents of the mind into linear strings of arbitrary symbols, Armstrong asserts that this model does not characterize signed languages. He shows that language is inherently a multichannel activity, of which the two primary channels are auditory and visual. Original Signs employs a more expansive notion of language that takes into account the full range of human communicative behavior. By making no strict separation between language and gesture, this thought-provoking work reveals that the use by deaf people of signs to create a fully formed language is also a natural facet of communication development for hearing people. Armstrong explores the influences of Plato and Descartes on modern linguistics, and delineates the theories of earlier anthropological linguists Edward Sapir and Benjamin Lee Whorf, who thought of language as natural experiments connected to individual cultures. This exceptional work of scholarship methodically demonstrates that the intricacies of how languages develop, whether they depend upon words or signs, and that the complexity among languages that contact one another cannot be accounted for by the sequential hierarchical processes previously put forth by linguists and logicians. Original Signs will prove to be a fascinating, watershed work invaluable to linguists, anthropologists, and all other scholars and students engaged in the search for the origin of language.