A Pre-Homo sapiens Vowel Inventory Preserved in the Śivasūtras: Evidence from Comparative Primatology and Hominin Vocal Tract Evolution

This paper estimates the terminus post quem and terminus ante quem for the phonemic inventory (varṇamālā) preserved in the Śivasūtras using paleoanthropological evidence of vocal tract evolution. The provisional terminus post quem (~7 Ma) is established by the phylogenetic emergence of consonantal production capacity at the Homo–Pan divergence. The terminus ante quem (~430 ka) is constrained by the loss of the anatomical ability to produce the vowels ऋ and ऌ as described in the Pāṇinīya Śikṣā and Ṛgveda–Prātiśākhya. These vowels require tongue root articulation at the hard palate and teeth, respectively, which became anatomically impossible following laryngeal descent in Homo sapiens. The phonemic system preserved in the Śivasūtras thus reflects vocal tract constraints of pre-sapiens hominins, likely Homo erectus or related species. This hypothesis generates falsifiable predictions through acoustic modeling of reconstructed Homo erectus sensu lato vocal tracts and accounts for otherwise anomalous features including the absence of contrastive आ and retention of dual ह distinctions. Cultural transmission of this inherited phonemic system through at least 430,000 years of linguistic continuity was maintained through structured teaching practices, with the Śivasūtras representing a systematic formalization of humanity’s phylogenetically deepest language substrate.