From the Mouths of Babes

Babies may seem to have little to say to linguists. But new findings in the 21 April Science suggest that the characteristics of language may originate in babbling sounds that all babies make.

Scientists more or less accept baby babble as a lingua franca. By the time they are 10 months old, babies around the world begin to babble, and they all say pretty much the same thing: "Ya-ya-ya," "ba-ba," "ma-ma-ma," etc. It's the sound of our vocal apparatus exploring many notes, before the brain learns the musical score for adult speech.

Psychologist Peter MacNeilage and development specialist Barbara Davis of the University of Texas, Austin, wanted to know whether this babbling is random or favors certain sounds. They listened to the babble and first words of 10 infants being raised by English speakers and ranked how often the babies made different kinds of vocalizations. They found two predispositions in infantspeak. In one, babies tend to use certain vowels to follow classes of consonants defined by where they have to place their tongues. In the other, babies tend to form words that start with pressing the lips together and end with the tongue toward the front of the mouth, as in "pot." Analyzing adult English speech, the researchers found that the two predispositions of infants persisted in the speech of adults and, in a sense, predicted the preponderance of different sounds.

The way the mouth, tongue, and other vocal apparatus are shaped and move relative to one another might explain the preference for these sounds, says linguist John Locke of Cambridge University in the United Kingdom. But cognitive scientist Philip Lieberman of Brown University in Providence, Rhode Island, disagrees. Speech contains certain sounds not because they are easy to make but because they are easy to hear, he says. Babies share predispositions with adults, he says, because they are trying to mimic our speech--even if it doesn't sound like it.