Human history is commonly understood to begin with the appearance of the first written document; anything that happened before the advent of writing is regarded as belonging to prehistory. And in western culture, the earliest systematic conventions for the format of graphic communication of words were developed in the Sumeric period, approximately 3,000 years BCE. But the intentional practice of marking stone, ivory, or bone with signs, figures and etchings had been cultivated for thousands of years before the appearance of written language. In fact, the very practice of writing derives from the earlier practice of drawing. According to the most accurate recent estimates (1), Paleolithic art dates back as far as the European cave etchings of 30,000 years ago.