I've heard that story about the cuneiform writing being commercial, but consider the following: "The cuneiform script (IPA pronunciation: [kjuˈniəˌfɔrm, ˈkjuniə-]) is one of the earliest known forms of written expression. Created by the Sumerians from ca. 3000 BC (with predecessors reaching into the late 4th millennium Uruk IV period[1]), cuneiform writing began as a system of pictographs. Over time, the pictorial representations became simplified and more abstract. . . . "Originally, pictograms were drawn on clay tablets in vertical columns with a pen made from a sharpened reed stylus, or incised in stone. This early style lacked the characteristic wedge-shape of the strokes. "Certain signs to indicate names of gods, countries, cities, vessels, birds, trees, etc., are known as "determinants", and were the Sumerian signs of the terms in question, added as a guide for the reader. Proper names continued to be usually written in purely "ideographic" fashion. "From about 2900 BC, many pictographs began to lose their original function, and a given sign could have various meanings depending on context. The sign inventory was reduced from some 1,500 signs to some 600 signs, and writing became increasingly phonological. Determinative signs were re-introduced to avoid ambiguity. This process is directly parallel to, and possibly not independent of, the development of Egyptian hieroglyphic orthography." . . . This from Wikipedia. Other uses for writing mentioned include letters, reports of battles, inscriptions of the achievements of kings on stelae, and lists of the names of gods. Chinese writing is perhaps older . . . "The origin of Chinese writing is commonly placed around the XIV century b.C., around 3400 years ago. The first real "characters" are those found on the bones used for divination under the Shang and Zhou dynasties, which form the so-called jiagu wen."
From http://www.geocities.com/Tokyo/Palace/1757/scrittura/scritturastoria.htm
Divination and naming the gods seem intuitively more likely motivators for writing than commerce. Also consider Altamira--14-18 millenia ago. When does a stick figure become a pictograph? Is all communication voodoo? Shamanism? Hunting and gathering? Cheers, Robert