Soru

Passage:

For over a century following the discovery of the Bronze Age Harappan civilization in the Indus River basin, scholars generally operated under the assumption that the thousands of brief, pictographic inscriptions incised upon steatite seals, copper tablets, and ceramic vessels represented a fully developed, albeit undeciphered, writing system. Epigraphists like Asko Parpola argued that the corpus—consisting of approximately four hundred distinct signs with an average inscription length of fewer than five characters—encoded an ancestral Dravidian language through phonetic rebus principles. Under this prevailing paradigm, the brevity of the inscriptions was attributed to their specialized administrative function as personal seals, property markers, and trade tokens, rather than as narrative texts, religious scriptures, or historical annals.

In 2004, however, a contentious thesis advanced by comparative historian Steve Farmer, computational linguist Richard Sproat, and Indologist Michael Witzel challenged the foundational premise of Harappan literacy. They contended that the Indus signs did not encode spoken language at all, but rather functioned as non-linguistic ideological symbols, akin to heraldic insignia, religious emblems, or clan motifs prevalent in other non-literate ancient societies. Central to their argument was the total absence of long texts; despite extensive archaeological excavations yielding thousands of artifacts across hundreds of settlements, the longest single inscription on a single surface contains merely seventeen signs, and the longest overall inscription across multiple surfaces contains only twenty-six. Farmer and his colleagues argued that no known ancient civilization maintained a genuine writing system exclusively restricted to minuscule string lengths without producing surviving monumental inscriptions, agricultural ledgers, or extensive administrative accounts on durable media.

Moreover, the structural behavior of the sign sequences presented anomalies difficult to reconcile with natural language phonology. Statistical analyses revealed a disproportionate number of "singletons"—signs that appear only once in the entire excavated corpus—alongside strict directional positional regularities that lack the flexible combinatory syntax typical of phonetic or logographic scripts. While proponents of the linguistic model countered that the high frequency of singletons reflects the incomplete sampling of a large, complex logophonetic sign list and pointed out that Egyptian and Mesopotamian proto-cuneiform also exhibited high singleton rates in their earliest phases, Farmer noted a critical divergence: early Near Eastern scripts rapidly evolved into discursive, long-form narrative texts within centuries of their emergence. By contrast, the Indus sign system maintained an immutable brevity and structural stasis for over seven hundred years during the Mature Harappan period (circa 2600–1900 BCE) before disappearing entirely alongside urban decline, exhibiting none of the evolutionary trajectories characteristic of true writing.

Based on the passage, which of the following is explicitly stated regarding the structural and physical characteristics of the discovered Indus inscriptions?