This essay explores a nineteenth-century debate over the linguistic capacity of animals in order to consider the links among language, reason, and history. Taking the American animal-protection movement as a point of departure, I show how protectionists, linguists, anthropologists, and advocates of deaf education were divided about the origins and nature of language. Was language a product of the soul and thus unique to humans, or was it a function of the body, a complex form of the corporeal expressions that humans and animals shared? Was language divine or natural? The answers that different activists and intellectuals gave to such questions shaped their view of the relationship of humans to animals and the inclusion of the latter in the moral and political community. I suggest that such debates are helpful to historians since the possession of language—and its traces in the written word—has traditionally been used to divide prehistory and natural history from history proper. If we are to include animals in “history,” we must rethink the relationship of the discipline to language.