Darwin made a famous comment about parallels between changes in language and species change. Gregory Radick, Professor of History and Philosophy of Science at Leeds University, talks about the importance of the development of language to Darwin, what Darwin's letters tell us about his thinking, and assesses Darwin's impact on later study.

How and why language evolved bears on larger questions about the evolution of the human species, and the relationship between man and animals. Darwin presented his views on the development of human speech from animal sounds in The Descent of Man (1871), but he had been interested in the origin of language since the late 1830s. Darwin's correspondence reveals the scope of his thinking about the evolution of language, how his views changed over time, and the array of people-from expert linguists, to naval officers, to bankers-with whom he exchanged information and ideas.

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.