Language vs. Speech

Although in colloquial parlance we rarely distinguish between language and speech, in actual fact the two are different. Speech is a physiological phenomenon. It involves the use of the organs of the vocal apparatus—the tongue, the teeth, the epiglottis, etc.—to deliver language, which is a mental code. Language is commonly delivered
as... speech; but it can also be expressed through other media, such as the alphabetic and the gestural ones. One can have language without speech, as do individuals with impaired vocal organs, because it exists as a mental code. But one cannot, clearly, have speech without language.


There is a strong possibility that language developed before speech in the human species. The evidence, however, is indirect. At birth, the larynx in human infants is high in the neck, as it is in other primates. Infants breathe, swallow, and vocalize in ways that are physiologically similar to gorillas and chimps. But, some time around the first three to six months of life, the infant's larynx starts to descend gradually into the neck, dramatically altering the ways in which the child will carry out laryngeal physiological functions from then on. Nobody knows why this descent occurs. It is an anatomical phenomenon that is unique to humans.

This new low position means that the respiratory and digestive tracts now cross above the larynx. This entails a few risks: food can easily lodge in the entrance of the larynx, and humans cannot drink and breathe simultaneously without choking. But in compensation, it produces a pharyngeal chamber above the vocal folds that can modify sound.
The lowered larynx makes it possible for human beings to articulate sounds with the vocal apparatus. The specific sounds that are used in a language to make up vocal signifiers are called phonemes. The phoneme is a minimal unit of sound that allows people who speak a language to differentiate its words. For example, what keeps words such as sip and zip distinct is the first sound. The phonemic difference between s and z can be discerned in the vibration of the vocal cords in the larynx. Putting an index and middle finger over the larynx and articulating these two sounds will immediately make the difference between s and z quite evident—the cords vibrate during the pronunciation of z, but not of s. The two sounds are otherwise articulated in the same way. Phonemic distinctions are perceived by the hearing center of the brain and produced through its motor pathways via a complex system of coordination between brain and vocal organs.

There are twelve cranial nerves. Seven of these link the brain with the vocal organs. Some perform a motor function, controlling the movement of muscles, while others perform a sensory function, sending signals to the brain. The larynx controls the flow of air to and from the lungs, so as to prevent food, foreign objects, or other substances from entering the trachea on their way to the stomach. The ability to control the vocal folds makes it possible to build up pressure within the lungs and to emit air not only for expiration purposes, but also for the production of sound. These physiological conditions were prerequisites for the development of vocal speech in the species too. Interestingly, research on the casts of human skulls has established that the lowering of the larynx did not take place earlier than 100,000 years ago. This is fairly persuasive evidence that there may have been language without speech in pre-Homo Sapiens species. The most probable mode of delivery of language was gesture. When speech became physiologically possible, it is likely that it was used in tandem with the previous gestural signs, not replacing them completely. This is the most likely reason why we still use gesture as a default mode of communication (when vocal speech is impossible), and why we gesticulate when we speak.