One of the things that seemed fascinating to me in chapter 8 was the description about how infants learn how to communicate. I never thought about how quick and important their developments at an early age are.
The auditory systems of the unborn infants develop by the fifth month of pregnancy and they can identify the voice of their mother and recognize their native language. This recognition was tested by measuring how much the infants sucked on the pacifier when they heard the mother's native language and an unfamiliar language. It was apparent for the researchers that there was more sucking when the baby heard the mother's native language even when a complete stranger was speaking.
As the infants continue to develop they begin to babble. The babbling, which refers to meaningless intentional vocalization, is important because the babies begin to use their vocal cords to familiarize themselves with the phonemes of their native language. It also helps them to fine-tune the vocal tracts and the ears to adjust to their own language.
This video from YouTube shows us what looks like a meaningful conversation between two infants. Before reading the chapter I would've just said "That's so cute!", but now I see this as quite an impressive phenomenon!
Also it was interesting to find out that comprehension of the speech occurs actually way earlier than the production of it in infants. The production occurs at about the age of one, but comprehension could happen months in advance. The growth of the vocabulary grows gradually, but later on the rate increases and by the time the child goes to kindergarten he or she may know several thousand words.
In addition, an important milestone in speech development occurs when the kids move from one word sentences to using several words at once. More syntactic rules continue to develop during early years of school.