Babies can say volume without saying a single word. They can wave good-bye, point at things to indicate an interest or shake their heads to mean "No". These gestures may be very simple, but they are a sign of things to come. Year-old toddlers who use more gestures tend to have more expansive vocabularies several years later...
Children gesture before they learn to speak and previous studies have shown that even among children with similar spoken skills, those who gesture more frequently during early life tend to know more words later on...
These early differences had consequences later. A child's "gesture vocabulary" at 14 months of age predicted the number of words they knew between the ages of four and five...
Text and image credit to
Not Exactly Rocket Science. More at the link, including a discussion of the correlation of such gesturing with socioeconomic status.
