Hypothesis of an Indo-Pacific Maritime Koiné: Typological, Quantitative, and Archaeological Evidence

This is an English translation of the original Spanish-language publication: "Hipótesis de una Koiné Marítima Indo-Pacífica: Evidencia Tipológica, Cuantitativa y Arqueológica" . Theoretical framework, methodology, data, and conclusions are identical to the original. (10.5281/zenodo.19371905) This study documents the hypothesis of an Indo-Pacific maritime koiné: a contact lingua franca operating within Middle Holocene trade networks (c. 4000–3000 BCE), whose structural and lexical traces survive in ten language isolates: Georgian, Tiwi, Puquina, Basque, Sumerian, Hurrian, Meluhhan, Ainu, Burushaski, and Elamite. The central mechanism is water as both connector and separator: maritime routes first linked coastal populations across three oceans, producing a shared nautical lingua franca; then synchronic aquatic catastrophes — marine transgressions, coastal floods, and the globally documented 4.2 ka BP event (c. 2200 BCE) — destroyed those routes and forced populations toward mountain and insular refugia. The hypothesis is built upon six independent and converging lines of evidence: Typological and quantitative analysis: Zipf's law, KL divergence, and an original Relative Morphological Complexity (RMC) index demonstrate that the ten languages form a statistically coherent cluster (mean RMC 1.260, intra-cluster DKL 0.28), separated from five negative control groups (mean RMC 0.916, p < 0.001). The correlation between degree of geographic isolation and morphological complexity is robust (r = 0.86, p < 0.01). Crucially, Turkish and Quechua — equally isolated SOV agglutinative languages — fall outside the cluster, demonstrating that isolation alone does not explain the convergence: a shared historical substrate is required. The man- root as a nautical lexical marker: The root man- (variants ma-, min-), associated with aquatic and maritime concepts — water, fish, seabird, crocodile, water spirit, harpoon — is distributed along the entire proposed network: from Sumerian and Hurrian in Mesopotamia, through the Munda and Aslian languages of the Indian Ocean corridor, the Aru languages in the Moluccas, Ainu and Old Japanese in Japan, Tiwi in Australia, Bijagó on the African Atlantic, and Matanawí in the Brazilian Amazon. This root is systematically absent in the neighboring languages of each node — Wolof, Tagalog, Quechua, Pama-Nyungan, Dravidian — ruling out typological universals and recent areal contact. Its distribution follows with precision the course of archaeologically documented routes, and appears exclusively in languages whose populations underwent the coastal-to-refugium displacement described above. Non-basic cognates in technical and cultural domains: manpa 'crocodile' (Tiwi, Proto-Lower Sepik) documents the Sahul route with absolute phonetic identity; kumara/k'umar 'sweet potato' links Polynesia and the Andes with archaeological support from Caral (3rd millennium BCE); qabaŋ/wampo 'watercraft' suggests a shared maritime tradition; and mullu documents the ritual traffic of Spondylus shell since the 3rd millennium BCE. Archaeological and paleogeographic evidence: Spondylus routes from Ecuador to Caral, Bismarck obsidian documented as far as Fiji, Indus seals at Ur and Lagash, the Kuroshio Current as an experimentally verified navigation vector, and the paleogeographic reconstruction of now-submerged waypoints across the Atlantic, Indian, and Pacific Oceans. Genetic evidence: Studies published in Nature (Skoglund et al. 2015) document that Amazonian populations share 1–2% ancestry with populations from the Andaman Islands, New Guinea, and Australia — the "Population Y" signal — which cannot be explained by the Beringian land route and points to a transoceanic maritime corridor. Astronomical evidence: The Southern Cross receives convergent instrumental designations in four cultures separated by oceans: Chakana ('bridge') in the Andes, Yikurrupi ('anchor') in Tiwi, Te Punga ('anchor') in Māori, and Choiols ('path connecting earth and sky') in Tehuelche — two independently converging on 'anchor' for the same constellation. The absence of this pattern in Basque, whose astronomical tradition is pastoral rather than nautical, acts as a negative control delimiting the phenomenon to cultures with advanced astronomical navigation. The fragmentation mechanism is independently documented: the 4.2 ka BP event synchronically collapsed the Akkadian Empire, the Egyptian Old Kingdom, the Elamite Empire, and the Indus civilization. Historical analogues from Malay, Aramaic, and Swahili demonstrate that the fragmentation of maritime lingua francas into isolated refugia is a recurrent and documented phenomenon, producing exactly the observed pattern: total lexical divergence with deep structural conservation. The study includes predictive validation using three languages not part of the main analysis — Nihali (India), Haida (Pacific Northwest), and Sandawe (Tanzania) — selected blindly with respect to their quantitative values, confirming 22 of 26 model predictions. Sandawe, with an RMC of 1.51 and anomalous SOV order in the African context, suggests that the phenomenon reached the shores of the Indian Ocean and the refugia of the African Rift. The oral tradition of Haida — which preserves detailed narratives of rising waters that covered the valleys — constitutes independent cultural memory of the displacement event the model predicts. The hypothesis is presented as an interdisciplinary working proposal, open to independent validation. The document includes detailed quantitative analyses, comparative tables, data corpora, and an extensive bibliography spanning historical linguistics, maritime archaeology, paleoclimatology, and prehistoric population genomics.