The title given to Chapter 8 is Language, Thinking, and Reasoning. However, I found this title to be very simple in regards to the breadth of details that are provided in regards to the variety of ways people communicate around the world. As I skimmed through the chapter I had a goal of seeking out the section that talked particularly about sign language. They explain why sign language is categorized as a language because it contains all the four features of language: phonemes, words, syntax, and extralinguistic information. (Newport & Meier, 1985)
Though some may consider sign language talking through symbols, the various symbols are considered actual words to those using them. There are specific rules in regards to the way words are put together through signing, just like there is a correct way in our native languages. Since the chapter clearly describes that the developmental stages are similar for deaf and 'normal' hearing babies, I decided to explore why apes cannot speak and how extensive their ability to communicate through signing is.
The main reason scientists have been giving for why apes cannot speak is that some part of their anatomy (i.e. their vocal chords) we not built for speaking. (de Luce & Wilder 1983: 3) However, Koko.org describes how Koko the gorilla has been able to express feelings through over 1,000 words from the standard American Sign Language vocabulary along with other natural gestures native to gorillas. The following link will bring you to the website where you can look through a variety of images showing Koko's symbols. The YouTube video also provides a good historical exemplification of how important the practice of sign language has become and still is in our modern society today.
http://www.youtube.com/watch?v=Pmuu8UEi2ko (watch 1:00-3:40)
Other source used: http://www.davidmswitzer.com/apelang.html