From the Bible to Chomsky, it has been held that language arose suddenly in our species as a single, one-off event. In my new book The Truth About Language, I try to develop an account more compatible with the Darwinian theory of evolution. One of my claims is that language emerged, not from animal calls, but from manual gestures. Our predecessors communicated in intentional, often playful, fashion with their bodies, not with their voices. Primates also indulge in this kind of communication, often in play, but their calls, in contrast, tend to be fixed and stereotyped. Their gestures, I think, are more like language than their calls are.


Yet we talk. The question then is, how did speech come about? How did our forebears move from hand to mouth, from sight to sound?


Part of the answer lies in understanding that even speech is fundamentally gestural, made up of movements of lips, tongue, and larynx. Since you can’t see these gestures apart from lip movements, we evolved the capacity to add sound, so that the gestures can be picked up in the way the gestures alter sound patterns. But they’re still gestures. So language may have progressed gradually from manual gestures to vocal ones. Here is an extract from the book:


“The gradual transition from body to face to mouth is an example of miniaturization—a common feature of communication systems, as evidenced by present-day cell phones and microchips. My first lab computer was the size of a home refrigerator. Speech is of course much more compact than pantomime and much more energy efficient. I have been told that instructors of sign language often need massage after an exhausting day of moving their arms and bodies. In contrast, the physiological costs of speech are so low as to be nearly unmeasurable. In terms of the energy expended, speech adds little to the cost of breathing, which we must do anyway to keep alive. Some people never seem to tire of talking.


With the production of language neatly tucked away into the mouth, the rest of the body, and especially the hands, were largely freed for other activities—a second freeing, as it were, after upright walking relieved the hands from locomotory duty. So the devil again found things for idle hands to do. These no doubt included the making and use of tools and weapons, writing and drawing, and gentle evening games of tennis.

These activities would have been inhibited, or perhaps would never have evolved, had we persisted with manual language, a point that did not escape the attention of Charles Darwin: “We might have used our fingers as efficient instruments, for a person with practice can report to a deaf man every word of a speech rapidly delivered at a public meeting, but the loss of our hands, while thus employed, would have been a serious inconvenience.”
If we’d kept our mouths shut, though, we might have lived in a much simpler world.