Drawing is one of the oldest forms of human
expression, with evidence for its existence preceding that of written
communication.
It is believed that drawing was used as a
specialised form of communication before the invention of the written
language, demonstrated by the production of cave and rock paintings
around 30,000 years ago (Art of the Upper Paleolithic).
These drawings, known as pictograms, depicted objects and abstract
concepts. The sketches and paintings produced by Neolithic times were
eventually stylised and simplified in to symbol systems (proto-writing)
and eventually into early writing systems.
For more of the history of drawing, go to:
Drawing Wikipedia page