Darwin started thinking about the origin of language in the late 1830s. The subject formed part of his wide-ranging speculations about the transmutation of species. In his private notebooks, he reflected on the communicative powers of animals, their ability to learn new sounds and even to associate them with words. “The distinction of language in man is very great from all animals”, he wrote, “but do not overrate—animals communicate to each other” (Barrett ed. 1987, p. 542-3). Darwin observed the similarities between animal sounds and various natural cries and gestures that humans make when expressing strong emotions such as fear, surprise, or joy. He noted the physical connections between words and sounds, exhibited in words like “roar”, “crack”, and “scrape” that seemed imitative of the things signified. He drew parallels between language and music, and asked: “did our language commence with singing—is this the origin of our pleasure in music—do monkeys howl in harmony”? (Barrett ed. 1987, p. 568).
The origin of language was widely studied and controversially debated in the Victorian period in a variety of fields, including comparative philology and linguistics, philosophy, anthropology, and psychology. Some argued that human speech derived from natural, instinctive utterances that were shared with some animals, and that languages developed and spread gradually according to various natural laws and processes. Proponents of the natural language theory included Darwin’s cousin, Hensleigh Wedgwood, the liberal Anglican scholar Frederic Farrar, the German philologist August Schleicher, and the American philologist William Dwight Whitney. Others argued that language was uniquely human, a manifestation of man’s higher nature and an instrument of his reason. Its origin was divine, and its development more akin to an art, than to any purely natural process. The leading advocate of this natural theological view of language was Friedrich Max Müller, a German linguist and oriental scholar who had emigrated to Britain and who eventually obtained a professorship at Oxford. In a series of influential lectures delivered several years after Darwin’s Origin of Species, Max Müller asserted that language was the “one great barrier between the brute and man”; “no process of natural selection will ever distil significant words out of the notes of birds and the cries of beasts” (Müller 1861, 1: 22-3, 354).
Darwin eventually published his views on language in Descent of Man (1871), as part of a chapter on the comparative mental powers of humans and the lower animals. He acknowledged that language had “justly been considered as one of the chief distinctions between man and the lower animals”; but he went on to emphasize the similarities between animal and human communication. Darwin’s arguments were based on his broad knowledge of anthropology, language use and acquisition in children, linguistic pathologies, and the behaviour of a wide range of animals, wild and domestic. Much of this information had been gathered through correspondence, as well as observations of his own children and pets. Darwin described how language might have evolved through natural and sexual selection. He compared birds learning to sing to infants babbling. An early progenitor of man, he wrote, probably used his voice as did the male gibbon, to produce musical cadences for courtship, and to compete with other males. The origins of language as a system of signifiers, he added, might have evolved from the imitation of the sounds of various predators (growls and snarls, for example), which functioned as warning signs. Darwin addressed the natural theology of Max Müller and others by arguing that language use, while requiring a certain mental capacity, would also stimulate brain development, enabling long trains of thought and strengthening reasoning power. Vocalization in humans would be greatly enhanced by the development of other functions, especially the use of the hands. Finally, Darwin drew an extended analogy between the evolution of languages and species, noting in each domain the presence of rudiments, of crossing and blending, and of variation, and remarking on how each developed gradually through a process of struggle: “the survival of certain favoured words in the struggle for existence is natural selection” (Descent 1: 61).
Debates about the origin of language are still ongoing. Are there specific language centres in the human brain? Do comparable structures exist in the brains of primates? Are animals capable of using language in a structured way, and do they possess powers of reason? Did linguistic ability, such as the use of syntax, evolve gradually, or did it emerge rapidly or even all at once in some now extinct progenitor of the human race? Such questions, addressed in a variety of scientific disciplines, such as neurology, palaeoanthropology, and animal psychology, build upon the work of Darwin and his contemporaries, while taking that work in new directions.