Nature and Nurture
© W. Tecumseh Fitch
Vocal anatomy of orangutan, chimp and human
Holding a conversation requires many parts of the body to work together: the mouth, tongue, voice box and lungs, as well as the ears and the brain. Perhaps the most impressive and uniquely human of these structures is the brain. It creates and recombines thousands of symbols to generate language others can understand. And the brain can understand what other people are saying. Although nature provides us with a brain and a vocal tract for language, the particular words and grammar of the language we learn come from the other humans around us.
How It Works
Children teach themselves a native language simply by listening and watching the people around them. This can happen with any language from Navajo to Nepali. As children get older, their brains become "wired" for the languages they've learned. This explains why learning to speak a new language fluently is usually harder for adults.
Humans are all born with brains that can absorb language rules. Certain genes help to shape the brain's language capacity. In one Pakistani family, for example, half the members carry a mutation in the FOXP2 gene that impairs their language skills. They have trouble speaking certain sounds and understanding grammar. Many genes are believed to work together to shape our language ability.
Deaf children in Nicaragua invented their own unique sign language in the 1980s--their country's first language for the deaf. The structures of such spontaneously emerging languages support the theory that all human brains contain the same underlying capacities for learning language.
So To Speak
Human speech depends on many parts of the mouth, tongue and throat. We generate vowel sounds by vibrating the vocal cords in the larynx, and then shaping that sound with the tongue and other parts of the vocal tract. Apes don't have such a long, moldable space between the larynx and mouth, so they can't make the sounds of human speech.
Did you Know?
Like chimps and other apes, human infants can breathe and swallow at the same time because their larynxes are much higher in the throat than an adult's.
Feel your tongue, lips and throat change shape as you say the words "beet," "boot," "bought" and "bat." Subtle adjustments like these enable humans to speak quickly and efficiently.