Proto-Dravidian as the Spoken Language of the Mature Harappan Civilization: A Five-Domain Convergence Analysis

This deposit establishes intellectual priority over the following finding: across five independent lines of evidence — structural, phonetic, metrological, biological, and archaeobotanical — Proto-Dravidian is the most parsimonious explanation for the spoken language of the Mature Harappan civilization (2600-1900 BCE). No alternative hypothesis — Indo-Aryan, Munda, or language isolate — produces consistent evidence across all five domains simultaneously. The structural foundation is established in Molina (2026e), FMX-IVT-2026-PUB: administrative frame signs survived the Harappan collapse selectively at Fisher p = 1. 62 x 10^-19, odds ratio 16. 7, with a medial sign control group achieving 0 out of 12 survival. The present paper assembles four additional domains around that structural backbone. The phonetic anchor is the sesame loanword ellu (DEDR 834), frozen in Akkadian and Sumerian cuneiform at the Harappan institutional peak (Ur III period, c. 2100-1900 BCE) with no Indo-Aryan etymology. Sanskrit tila is an unrelated term. The Dravidian match is exact across all major branches. The nautical term magilum (DEDR 4652) has no Indo-Aryan etymology. Sanskrit samara is confirmed by Kuiper (1991) and Witzel (1999) as a Dravidian substrate loan into Indo-Aryan — the borrowing direction confirms Dravidian speakers were in the contact zone before Indo-Aryan arrival. The cotton loanword chain provides a second independent phonetic anchor: Proto-Dravidian parutti / ek- (DEDR 3976) has no Indo-European cognate, and Sanskrit karpasa is acknowledged by mainstream linguistics as a substrate loan with no Indo-European etymology. The metrological domain connects the vocabulary of the world's first standardized commercial measurement system to Proto-Dravidian. The term vicam (DEDR 5424, 1/16 base unit) matches the most common Harappan weight unit. The term ma (DEDR 4780, 1/20 unit) is the complementary decimal fraction. The term kol (DEDR 2237, measuring rod/staff) matches ivory and copper measuring rods confirmed at Lothal and Mohenjo-daro. No Indo-Aryan cognates exist for any of the three terms. Source: Jeganathan (1998), RASK Vol. 8, pp. 69-102. The biological domain provides independent corroboration. Narasimhan et al. (2019, Science 365: eaat7487) confirmed absence of steppe (Indo-Aryan) ancestry in IVC skeletal samples, definitively excluding Indo-Aryan speakers from the IVC population during the Mature Harappan phase. Sequeira et al. (2025, European Journal of Human Genetics 33 (11): 1245-1256, DOI: 10. 1038/s41431-025-01963-1) identified a Proto-Dravidian ancestry component branching approximately 4, 400 years ago on the Indus periphery, coinciding with the Mature Harappan phase. Qualification stated explicitly: genetic continuity does not prove linguistic continuity. This domain is corroborating, not probative. The archaeobotanical domain documents the dispersal of sesame and cotton from Harappan core sites (Harappa, Mohenjo-daro, Mehrgarh) through the Deccan bridge (Daimabad, Nevasa) to Southern Neolithic sites (Hallur, Sanganakallu, Tekkalakota) along the same geographic corridor and temporal window as the sign survival evidence established in Molina (2026e). Cubical chert weights, sesame, cotton, and Indus-derived graffiti are confirmed co-located at all four corridor waypoints. The complete Meluhhan commercial package moved as a singular institutional unit, not as separately diffusing cultural elements. A novel theoretical contribution is established: the Rebus-Hypocorism Bridge. The rebus principle (Rogers 2005; Sampson 2015) explains how pictograms acquire phonetic values but does not explain which signs are selected for phonologization and which are discarded. This gap is confirmed by audit of Rogers (2005), Sampson (2015), Parpola (1994), and Mahadevan (2009). The Rebus-Hypocorism Bridge fills this gap: identity-marking tokens are socially embedded in name-giving and commercial declaration practices where hypocoristic compression operates — the same process that produces shortened familiar forms from full names across all languages. Signs used thousands of times in spoken transactions acquire stable phonetic forms. Signs used to record internal accounting quantities do not. The 0 out of 12 medial survival result is the empirical confirmation. The Keezhadi phonologization event is confirmed archaeologically. The TNSDA excavation report Keeladi: An Urban Settlement of Sangam Age (2019) documents two artifacts carrying both Indus-style graffiti marks and Tamil-Brahmi phonetic inscriptions on the same black-and-red ware surface — the Aathan sherd (TNSDA 2019, p. 14/18, Chapters 8 and 12) and the Kuviran-Aathan sherd. The report characterizes these artifacts as documenting a Journey from Graffiti to Brahmi. All 13 high-lock survivor signs identified in Molina (2026e) are confirmed present at Keezhadi. This deposit does not claim phonetic continuity between the Indus script and Brahmi. A bilingual text would close the phonetic identification definitively and does not yet exist. The claim is that Proto-Dravidian is the only linguistic hypothesis for which convergent multidisciplinary support is available across all five domains simultaneously. Full analytical methodology withheld pending peer-reviewed publication. SHA-256 of companion private deposit embedded in document. This deposit extends Molina (2026a-e) and FMX-IVT-2026-ADD. Reference: FMX-IP-2026.