Herbert S. Terrace


On his book Why Chimpanzees Can't Learn Language and Only Humans Can

Cover Interview of October 02, 2019

A close-up

I recommend a new reader turn to the chapter on the first year of infancy. Most people who spend time with infants (including their parents) think they are just playing and having fun. That’s of course true but virtually no one appreciates the structure and function of that play and how it inexorably leads to language.

Peter Hobson, a British psychoanalyst, has provided the best description I know of regarding the path to language: “Those psychologists who believe that humankind became unique by acquiring language are not altogether wrong. But they are not altogether right, either. Before language, there was something else more basic, in a way more primitive, and with unequalled power in its formative potential that propelled us into language. Something that could evolve in tiny steps, but suddenly gave rise to the thinking processes that revolutionized mental life. (...) That something else was social engagement with each other. The links that can join one person’s mind with the mind of someone else—especially, to begin with, emotional links—are the very links that draw us into thought.”

Those links begin with the practice of cradling and the opportunities cradling provides for social engagement. Among primates, only humans cradle their infants because new-born infants are the least developed. The volume of an infant’s brain is approximately 25 percent of its adult size; in chimpanzees, it’s 45 percent. Similarly, the human skeletal system is poorly developed.  As a result, an infant cannot locomote and must be cradled for six months.

An important benefit of cradling is the proximity of the infant’s and parent’s eyes, allowing them to share each other’s affect and gaze, one of many quirks of evolution that laid the groundwork for language. In compensation, as it were, for the infant’s lack of mobility, infant and parent can observe and anticipate each other’s behavior to an amazing degree during cradling. How many times have you heard, and likely said yourself, when watching a baby in their parent’s arms, look at how the baby’s eyes are soaking up knowledge — or words to that effect? Look how she watches other people. She’s like a sponge.

Developmental psychologists have shown that those interactions are rhythmic. Parent and infant take turns in expressing affect and in engaging in non-verbal auditory behavior (whimpering, gurgling, and so on). An important feature of those interactions is that they are conversational. After a mother smiles, raises her eyebrows, makes a sound, shakes her hands, and so on, so does the infant. Long before an infant utters her first words, she’s engaging in proto-conversations of affect with her mother and others.

While playing with an infant, it is commonplace for a parent to engage the infant’s interest in an object by looking at that object, waiting for the infant to gaze at it, and then look back at them and smile. Such examples of joint attention provide the first instance in which an infant and another person share the contents of their minds, in this example, knowing that each one saw a particular object.