第878页 Communication

Communication using language requires both a physical component - the central nervous system and muscle coordination - and cultural learning. Beginning early in life, human beings develop a basic understanding of several forms of communication. For example, babies about six months old begin to use hand gestures and distinct syllables simultaneously to express themselves. Face-to-face interaction with other people during the first three years of life is essential for a child to form the ability to communicate. 
 P879 form around 8000 B.C.  to 3000 B.C. ……
Over time, early writing systems became increasingly phonetic - that is, they used symbols to represent individual speech sounds instead of objects. They also became increasingly abstract - that is, they used symbols that represented ideas rather than actual objects. Eventually, writing became so abstract that it became alphabetic. Alphabets made it possible to write down anyword in the spoken language using comparatively few characters. Nonalphabet writing systems are still used in many parts of the world. In written Chinese, for example, each character stands for a word or part of a word.