Generations of archaeologists digging in humanity's earliest settlements ignored the unspectacular little artifacts of clay that turned up in so many Mesopotamian excavations. If they wrote about them at all, they called the thumb-sized balls, cones, disks and other shapes "enigmatic objects" or guessed they were merely children's toys.

Since the 1970s, however, a University of Texas specialist in Middle Eastern studies has been building a strong case that the objects are fundamental clues to nothing less than one of the most important advances in human intellectual evolution.

The hardened bits of clay, she has shown, reveal how the ancient Sumerians developed the world's first writing. They also strongly challenge the longstanding belief that Sumerian cuneiform, as the most advanced form of the writing is called, evolved from "picture writing" -- the use of little drawings, or pictographs, of real objects to stand for words.

More than that, according to the newest discoveries by Denise Schmandt-Besserat, professor of Middle Eastern studies at UT's Austin campus, the clay tokens, as she calls them, also tell how the Sumerians developed the concept of abstract numbers. In fact, her evidence suggests that the need to count led to the ability to write and that literacy and its mathematical equivalent, numeracy, rose in tandem, together transforming the nature of civilization.

Digging Into a Mystery

The French American scholar's discoveries have won high praise in a field noted for discord.

"Every so often, a field of study is revolutionized by a single discovery or a unique hypothesis," William W. Hallo, a Yale University expert in the ancient Middle East wrote of the new findings in a foreword to Schmandt-Besserat's monograph, "Before Writing," published earlier this year. Her research, Hallo said, "promises to play such a role in our understanding of the emergence of civilization."

The origin of writing had long been a puzzle. The oldest known examples have been found in digs at Uruk (the Biblical Erech), one of the major cities of Sumer, the world's first civilization. The Sumerian culture arose in the fertile Tigris and Euphrates river valleys of what is now Iraq, a region called Mesopotamia, about 5,400 years ago.

Sumerian writing emerged about three centuries later. About the same time, the ancient Egyptians developed their hieroglyphic writing. In later centuries, writing also arose -- probably independently -- in China and among the Maya of Central America.

At one time, some scholars supposed writing was the invention of individual geniuses who simply thought it up. More recently, it has been seen as the result of a gradual process. Until Schmandt-Besserat's research, however, the nature of that process had been elusive.

"My work on the clay tokens suggests that these were the early form of the activity that would become writing," Schmandt-Besserat said. She has discerned the roots of writing twice as far into the past as had been supposed -- to a time about 10,000 years ago when agriculture was just beginning to replace hunting and gathering.

The tokens first came to light in archaeological digs into strata of that antiquity in what is now Iran. The origin of token-making -- bits of clay formed by hand into balls, balls flattened into disks, oblongs, cylinders, cones, cubes and tetrahedrons -- it turned out, predated the manufacture of pottery. Tokens were, in fact, the first clay objects hardened by fire. About 10,000 of the objects have been found in more than 100 archaeological sites.

Schmandt-Besserat said major clues to their meaning came from two scholarly predecessors. In a 1966 paper Pierre Amiet, a specialist in Middle Eastern antiquities at the Louvre in Paris, suggested that the tokens were counters, pieces used to represent specific commodities. He cited an earlier discovery by Leo Oppenheim of the University of Chicago. This was a hollow clay ball found in the 1920s at a site near ancient Babylon that was occupied long after the invention of writing. The outside had a cuneiform inscription that read: "Counters representing small cattle: 21 ewes that lamb, 6 female lambs . . . " and so on until 49 animals were described. When workers broke open the ball, out tumbled 49 bits of fired clay.

Oppenheim speculated that the objects were part of an accounting system by which the local bureaucracy kept records.

On reading Amiet's paper, Schmandt-Besserat said, "two pieces of the puzzle snapped together for me." She immediately saw a link to the many tokens from sites occupied thousands of years before writing began. They too might have been part of a preliterate accounting system.

Schmandt-Besserat's subsequent research has shown that before the advent of writing, hollow clay balls were used as "bills of lading" to accompany shipments of goods. When a shipper delivered a cargo of jars of oil, for example, he would surrender the clay ball to the recipient, who could break it open and confirm that the correct quantities had arrived.

In later years, the Texas scholar said, Sumerian accountants thought of a simple way to verify the contents of a ball without destroying it. They would press each token against the outer surface of the ball before it hardened, then put them through a hole and seal the ball. Soon after, the accountants realized that once they made the impressions, there was no need for the tokens. The shape of the token, showing in the hardened clay, carried the meaning.

Indeed, Schmandt-Besserat has found that the shapes correspond closely to the first kind of Sumerian writing, which has been called pictography but, which she stresses, is not very pictographic. The symbols are incised in wet clay with stylus but only a few of the symbols are pictorial; most are abstract shapes and correspond to the shapes left by tokens pressed in wet clay. A New Kind of Symbol

At least as important, she found the switch to "pictographic" writing came at the same time as another key intellectual advance. When tokens were used, each stood for one unit of a commodity. To indicate, say, 10 jars of oil, 10 "jar of oil" tokens would be put inside the clay ball. When writing appeared, the same meaning was conveyed by one "jar of oil" pictograph plus a new kind of symbol that meant "10."

"We knew there was something that had to come before writing," Schmandt-Besserat said. "Nobody in archaeology had asked what came before arithmetic. Mathematicians had predicted that something concrete had to come before abstract numbers. The tokens were the concrete numbers. When writing begins, mathematics begins."

She said it looks as if the same intellectual leap of symbolizing that led to incising the token shapes also led to thinking of numbers as something apart from what is being counted.

A century after "pictographic" writing began, the curving symbols were converted to the more angular form created by square-cornered styluses being pressed into clay. The result was the cuneiform (from the Latin for "wedge-shaped") writing that quickly swept the ancient Middle East.