THE ART OF WRITING is a good example of what students of the past call independent invention, since systems of writing have evolved in isolation at different times in different parts of the world.

For example, one system - the Chinese ideogram - can be traced to its origin in archaic signs engraved on the scapular bones of sheep or the shells of turtles in the second millennium B.C. as a means of asking questions of heaven.

Roughly 1,000 years later, an entirely independent system of writing arose halfway around the world in Meso-America. It combined a simple system of numerical notation with complex hieroglyphs and was principally used to indicate the dates of various events according to an elaborate calendrical system.

Both Chinese and Maya writing were relatively late inventions. The credit for being the first to write texts is usually given to the Sumerians of Mesopotamia. By the last century of the fourth millennium B.C., the officials of such Sumerian city-states as Uruk had developed a system of recording numerals, pictographs and ideographs on specially prepared clay surfaces. (A pictograph is a more or less realistic portrayal of the object it is supposed to represent; an ideograph is an abstract sign.)

The clay blanks used by the Uruk scribes, universally referred to as tablets, are convex. Individual characters were inscribed in the clay by means of a stylus made of wood, bone or ivory, with one end blunt and the other pointed. The characters were basically of two kinds. Numerical signs were impressed into the clay; all other signs, pictographs and ideographs alike, were incised with the pointed end of the stylus. The repertory of characters used by the Uruk scribes is estimated at no fewer then 1,500 separate signs.

Hypotheses about the origin of writing generally postulate an evolution from the concrete to the abstract; an initial pictographic stage that in the course of time and perhaps because of the carelessness of scribes becomes increasingly schematic. The Uruk tablets contradict this line of thought. Most of the 1,500 signs are totally abstract ideographs; the few pictographs represent such wild animals as the wolf and the fox or items of advanced technology such as the chariot and the sledge.

Indeed, the Uruk texts remain largely undeciphered and an enigma to epigraphers. The few ideographic signs that have been identified are those that can be traced back stage by stage from a known cuneiform character of later times to an archaic Sumerian prototype. From the fragmentary textual contents that such identities allow, it appears that the scribes of Uruk mainly recorded such matters as business transactions and land sales. Some of the terms that appear most frequently are those for bread, beer, sheep, cattle and clothing.

After the German archeologist Julius Jordan's discovery at Uruk, others found similar texts elsewhere in Mesopotamia. More were found in Iran: at Susa, at Chogha Mish and as far off as Godin Tepe, some 200 miles north of Uruk. In recent years, tablets in the Uruk style have been unearthed in Syria at Habuba Kabira and Jebel Aruda, nearly 500 miles to the northwest. At Uruk, the tablets had been found in a temple complex; most of the others came to light in the ruins of private houses, where the presence of seals and the seal-marked clay stoppers for jars indicate some kind of mercantile activity.

The fact that the Uruk texts contradict the hypothesis that the earliest form of writing would be pictographic has inclined many epigraphers to the view that the tablets, even though they bear the earliest known writing, must represent a stage in the evolution of the art that is already advanced. The fact that no writing of this kind has yet appeared at site of the fourth millennium B.C. and even earlier is explained away by postulating that the writing of earlier millenniums was recorded exclusively on perishable mediums that vanished long ago, such as parchment, papyrus or wood. Clues in the Clay

I HAVE AN ALTERNATIVE proposal. Research into the first uses of clay in the Near East over the past several years suggests that several characteristics of the Uruk material provide important clues to what kinds of visible symbols actually preceded the archaic Sumerian texts. These clues include the choice of clay as a material for documents, the convex profile of the Uruk tablets and the appearance of the characters recorded on them.

Nuzi, a city site of the second millennium B.C. in Iraq, was excavated by the American School of Oriental Research in Baghdad between 1927 and 1931. Nearly 30 years later, reviewing an analysis of the Nuzi palace archives, A. Leo Oppenheim of the Oriental Institute of the University of Chicago reported the existence of a recording system that made use of "counters," or tokens.

Oppenheim visualized a kind of dual bookkeeping system in the Nuzi texts; in addition to the scribes' elaborate cuneiform records the palace administration had parallel tangible accounts. For example, one token of a particular kind might represent each of the animals in the palace herds.

The discovery of a hollow egg-shaped tablet in the palace ruins supported Oppenheim's hypothesis. The inscription on the face of the tablet turned out to be a list of 48 animals. The hollow tablet rattled, and, when one end of it was carefully opened, 48 tokens were found inside. Presumably the combination of a written list and countable tokens represented a transfer of animals from one palace service to another. Unfortunately we have no accurate description of the tokens; they were subsequently lost.

The Nuzi archives are dated to about 1500 B.C. The great Elamite site, Susa, has levels that are more than 1,500 years older. Six years after Oppenheim's 1958 report, Pierre Amiet of the Louvre Museum was able to confirm the existence of a similar accounting system at Susa. The token containers at Susa, unlike the container from Nuzi, were hollow clay spheres. Amiet called them "bullae"; so far about 70 of them have been found. The tokens they contain are clay modeled in a variety of geometric forms, including spheres, discs, cylinders, cones and tetrahedrons. First Farming Settlements

AMIET'S FINDING not only demonstrated that bullae and tokens were in existence at least a millennium and a half before they appeared at Nuzi but also showed that they were as old or older than the earliest written records at Uruk. Indeed, it later became clear that the tokens, at least, were very much older.

In 1969, I visited museums in the United States, Europe and the Middle East that had collections of clay artifacts dating back to the seventh, eighth and ninth millenniums B.C. This interval of time, beginning around 11,000 years ago and ending a little more than 8,000 years ago, saw the firm establishment of the first farming settlements in western Asia.

I encountered what was to me an unforeseen category of objects: small clay artifacts of various forms. As I later came to realize, the forms were like those Amiet had found inside his Susa bullae: spheres, discs, cones, tetrahedrons, ovoids, triangles (or crescents), biconoids (double cones joined at the base), rectangles and other odd shapes difficult to describe. Could these artifacts, some of them 5,000 years older than the tokens from Susa, also have served as tokens?

I found that whereas all of the tokens were small, measuring on the average from 1 centimeter to 2 centimeters in their greatest dimension, many were of two distinct sizes. There were small cones about a centimeter high and large cones 3 or 4 centimeters high. There were also thin disks, only 3 millimeters thick, and thick ones, as much as 2 centimeters thick. In addition to whole spheres I found quarter, half and three-quarter spheres. Many were incised with deep lines; some had small clay pellets or coils on them and others bore shallow circular punch marks.

I found that the tokens were present in virtually all museum collections of artifacts from the Neolithic period in western Asia. Reports generally indicate that the excavators found the tokens scattered over the floors of houses located in various parts of a site.

As I reviewed the museum collections and the related site reports, I became increasingly puzzled by the apparent omnipresence of the tokens. They had been found in sites from as far west as Beldibi in what is now southwestern Turkey to as far east as Chanhu Daro in what is now Pakistan. Tokens had even been unearthed at an eighth millennium B.C. site on the Nile near Khartoum.

I had compiled a catalogue of hundreds of tokens before I realized how much like Amiet's tokens from Susa these far earlier clay artifacts were. At first it seemed impossible that the two groups could be related; a minimum of 5,000 years separated the tokens of Neolithic times from those of Bronze Age Susa. As I extended my investigations to include later clay artifacts, dating from the seventh millennium B.C. to the fourth millennium and later, I found to my surprise that similar clay tokens had been found in substantial numbers at sites representative of the entire time span. Evidently a system of accounting that made use of tokens was widely used, not only at Nuzi and Susa but throughout western Asia from as long ago as the ninth millennium B.C. to as recently as the second millennium.

The system had some 15 major classes of tokens, further divided into some 200 subclasses on the basis of size, marking or fractional variation, as in the case of the quarter, half and three-quarter spheres. Evidently each particular shape had a meaning of its own; a few appear to represent numerical values and others specific objects, commodities in particular.

A number of ideographs on the Uruk tablets almost exactly reproduce in two dimensions many of the tokens. For example, Uruk arbitrary signs for numerals, such as small cone-shaped impression for the number one, a circular impression for the number 10 and a larger cone-shaped impression for the number 60 are matched by tokens: small cones, spheres and large cones. Further examples of ideographs that match tokens include, under the general heading of commodities, the Uruk symbol for sheep (a circle enclosing a cross), matched by disc-shaped tokens incised with a cross, and the Uruk symbol for a garment (a circle enclosing four parallel lines), matched by disk-shaped tokens incised with four parallel lines. Still other examples are ideographs for metal and oil and more clearly pictographic symbols for cattle, dogs and what are evidently vessels; each tablet sign can be matched with a similarly shaped and marked token.

Why did such a repertory of three-dimensional symbols come into existence? It cannot simply be a coincidence that the first tokens appear early in the Neolithic period, a time of profound change in human society. It was then that an earlier subsistence pattern, based on hunting and gathering, was transformed by the impact of plant and animal domestication and the development of a farming way of life. The new agricultural economy, although it undoubtedly increased the production of food, would have been accompanied by new problems.

Perhaps the most crucial would have been food storage. Some portion of each annual yield had to be allocated for the farm family's own subsistence and some portion had to be set aside as seed for the next year's crop. Still another portion could have been reserved for barter with those who were ready to provide exotic products and raw materials in exchange for foodstuffs. It seems possible that the need to keep track of such allocations and transactions was enough to stimulate development of a recording system.

The earliest tokens now known are those from two sites in the Zagros region of Iran: Tepe Asiab and Ganj-i-Dareh Tepe. The people of both communities seem to have tended flocks and were possibly experimenting with crops around 8500 B.C., although at the same time they continued to hunt game and gather wild plants. The clay tokens they made were quite sophisticated in form. There were four basic types of token spheres, discs, cones and cylinders. In addition there were tetrahedrons, ovoids, triangles, rectangles, bent coils and schematic animal forms. Subtypes included half-spheres and cones, spheres and discs with incisions and with punch marks. The set totaled 20 individual symbols.

The Neolithic period and the succeeding Chalcolithic period, or Copper Age, in western Asia lasted about 5,000 years. Over this substantial span one finds surprisingly few changes in the tokens, a fact that may indicate how well suited to the needs of an early agricultural economy this recording system was.

Early in the Bronze Age, between 3500 and 3100 B.C., there were significant changes. This period saw an economic advance quite as remarkable in its own way as the rise of the farming economy that laid the foundation for it. The new development was the emergence of cities. Surveys of ancient sites in western Asia indicate a drastic increase in the population of Iraq and Iran; urban centers with many inhabitants begin to appear close to the earlier village settlements.

The development of an urban economy, rooted in trade, must have multiplied the demands on the traditional recording system. Not only production but also inventories, shipments and wage payments had to be noted, and merchants needed to preserve records of their transactions. By the last century of the fourth millennium B.C., the pressure of complex business accountancy on the token system becomes apparent both in the symbols and in how the tokens were used.

Six sites of the late fourth millennium B.C. in Iraq (Uruk, Tello and Fara), in Iran (Susa and Chogha Mish) and in Syria (Habuba Kabria) have yielded tokens representative of the full range of early shapes. In addition, some new shapes appear, among them parabolas, rhomboids and replicas of vessels. Even more significant than the appearance of new shapes, however, is the great proliferation of subtypes indicated by a variety of incised markings on the tokens.

The six sites have yielded a total of 660 tokens dating to about 3100 B.C. Of this number, 363, or 55 percent, are marked with incisions. Most of the incisions are deep grooves made with the pointed end of a stylus; the grooves are placed conspicuously and with a clear concern of symmetry. A significant change at the end of the fourth millennium B.C. is the first appearance at this time of clay bullae, or envelopes, such as those Amiet found as containers of tokens at Susa. The existence of a bulla is clear-cut evidence of the user's desire to segregate the tokens representing one or another transaction.

There is no doubt in my mind that such bullae were invented to provide the parties to a transaction with the kind of smooth clay surface that according to Sumerian custom could be marked by the personal seals of the individuals concerned as a validation of the event. The fact that most of the 350 bullae so far discovered bear the impressions of two different seals lends support to my conviction.

Amiet has suggested that the Susa bullae may have served as bills of lading. In this view, a rural producer of textiles would consign a shipment of goods to an urban middleman, sending along with the shipment a bulla that contained a number of tokens descriptive of the kind and quantity of merchandise shipped. By breaking the bulla the recipient of the shipment could verify the makeup of the shipment; moreover, the need to deliver an intact bulla would inhibit the carrier from tampering with the merchandise in transit. This sealed transfer of tokens between trade partners represents an entirely new way of using the ancient recording system.

The innovation had one serious drawback. The seals impressed on the smooth exterior of the bulla served to validate each transmission, but if the seal impressions were to be preserved, the bulla had to remain intact. How, then, could one determine what tokens were enclosed and how many? A solution to the problem was soon found. The surface of the bulla was marked so that in addition to the validating seal impressions, it bore images of all the enclosed tokens. The Crucial Link

THE BULLA MARKINGS clearly were not invented to take the place of the token system of record keeping. Nevertheless, that is what happened. One can visualize the process. At first the innovation flourished because of its convenience: anyone could "read" what tokens a bulla contained and how many without destroying the envelope and its seal impressions.

What then happened was virtually inevitable, and the substitution of two-dimensional portrayals of the tokens for the tokens themselves would seem to have been the crucial link between the archaic recording system and writing. The hollow bullae with their enclosed tokens would have been replaced by inscribed solid clay objects: tablets. The strings, baskets and shelf loads of tokens in the archives would have given way to representative signs inscribed on tablets - that is, to written records. There can be little doubt about the relation between the shapes and markings of the tokens and the supposed arbitrary forms of many Uruk ideographs. No fewer than 33 clear-cut identities exist between the ideographs and two-dimensional representations of tokens and more than twice that many are possible.

Thus, the earliest examples of writing in Mesopotamia may not, as many have assumed, be the result of pure invention. Instead they appear to be a novel application late in the fourth millennium B.C. of a recording system that was indigenous to western Asia from early Neolithic times onward. In this view the appearance of writing in Mesopotamia represents a logical step in the evolution of a system of record keeping that originated some 11,000 years ago. CAPTION: Picture 1, Clay tokens from Susa, a city site in Iran, are about 5,000 years old; in the top row are the commonest shapes; the second row, more elaborate types with incisions or impressions; the last two rows, unperforated and perforated versions of similar tokens, Louve Museum photo; Picture 2, Twelve major types of tokens have been matched with incised characters in the earliest Sumerian inscriptions; where the meaning of the symbol is known, the English word appears with it., From "The Earliest Precursor of Writing" by Denise Schmandt-Besserat; Copyright (c) 1978, Scientific American, Inc. All rights reserved