The Cascajal block and Isthmian writing

The find is documented only as debris. About three quarters of the material collected with the block is Formative, nearly all of the San Lorenzo phase (uncalibrated 1200 to 900 BC) with a few Palangana sherds, and a quarter Terminal Classic; the authors placed the block late in San Lorenzo B, about 900 BC, also on the grounds that its motifs are Olmec and cannot be Classic⁠[1]⁠[2].

The stone and its working have been examined. Weathering, pitting over the incisions and mineralisation in the lines were reported in 2006 and confirmed by INAH's geological laboratory⁠[1]. The 2020 study added X-ray fluorescence matching the serpentinite to a source at Tehuitzingo, Puebla, used for Olmec stone, and electron microscopy showing incision with obsidian and abrasion with sandstone⁠[4].

The text's structure is partly described. Signs and short sequences repeat, some in pairs; Carrasco and Englehardt identified paired signs as possible diphrastic kennings of the kind known in later Mesoamerican texts, and Mora-Marín found a further repeated pair (PELT-PAW)⁠[6]. The reading order is disputed: horizontal rows in 2006, columns after a 90-degree turn in 2009⁠[2]⁠[5].

Authenticity has been tested more than anything else. Against the 2007 objections, the 2020 imaging and archaeometry found Olmec-source stone and ancient tool marks and patina, which makes a modern forgery on fresh stone unlikely; it does not test whether old stone was incised later⁠[4]⁠[3]. The date has not been tested independently, because no organic material is associated with the block and the debris is mixed⁠[1].

Whether the signs are writing has been tested by distribution. The 2006 authors argued from repetition and sequencing; Mora-Marín tested the proposed inventory against co-occurrence and argued that the irregularities others had noticed fit logosyllabic spelling⁠[2]⁠[6]. These are analyses of a single text of 62 signs, which limits what any statistic can show.

The Isthmian decipherment has had one formal test each way. Justeson and Kaufman reported in 1997 that a column on La Mojarra Stela 1 noticed in 1995, after their decipherment, read readily with their values⁠[12]. Houston and Coe applied the same values to the back of a Teotihuacan-style mask of unknown provenance, with about 101 glyphs, 25 of them new, and could not obtain a reading⁠[8]⁠[13].

Four positions on the Cascajal block are in print. It is writing, the earliest in Mesoamerica, possibly logosyllabic and possibly ancestral to later Isthmian writing⁠[2]⁠[6]⁠[14]. It is a ritual text whose signs belong to an Olmec vocabulary, an initiation rite on Magni's reading⁠[15]. It is not writing but an arrangement of sacred objects drawn in Olmec iconography⁠[16]. Or it is undatable and possibly a hoax, the view Bruhns and Kelker raised, with doubts also voiced by Grove and Pool⁠[3]⁠[10].

On Isthmian, Justeson and Kaufman read La Mojarra Stela 1 as the record of a ruler's accession, wars and rituals in an early Zoquean language; Houston and Coe, and Robinson in a later survey, regard the decipherment as unproven; Vonk has argued that the corpus is too small for any unique decipherment⁠[7]⁠[8]⁠[9]⁠[17].

Isthmian texts come from southern Veracruz and Chiapas; the oldest is a sherd of 450 to 300 BC and the longest dates to the second century AD. La Mojarra Stela 1, a four-ton limestone stela pulled from the Acula River in 1986 and now in the Museo de Antropología de Xalapa, carries about 535 glyphs and Long Count dates of AD 143 and 156; the Tuxtla Statuette, a nephrite figure found near Tres Zapotes in 1902 and held by the Smithsonian, has a possible date of AD 162⁠[17]⁠[18]. The rest of the corpus is short: Tres Zapotes Stela C, a few glyphs at Cerro de las Mesas, the O'Boyle mask, the Teotihuacan-style mask, and a sherd from Chiapa de Corzo of 450 to 300 BC⁠[9]. Kaufman and Justeson's working papers are archived at AILLA, some open and some restricted⁠[19].

For the block, a second inscribed Olmec object from a dated, excavated context would answer the uniqueness objection and anchor the date; residue or microstratigraphic analysis inside the incisions could test whether the cutting is as old as the patina⁠[4]⁠[3]. For both scripts, a machine-readable sign-by-sign transcription of every text in one numbering would allow the repeated-pair and co-occurrence claims to be tested against shuffled controls⁠[6]. For Isthmian, a new substantial text read with the 1993 values fixed in advance, by someone other than the decipherers, would decide it⁠[12]⁠[8].