Toto is a Sino-Tibetan language spoken on the border of India and Bhutan, by the tribal Toto people in Totopara, West Bengal along the border with Bhutan. It is also spoken in Subhapara, Dhunchipara, and Panchayatpara hillocks on India-Bhutan border in Jalpaiguri district, West Bengal (Ethnologue).
Toto is listed as a critically endangered language by UNESCO, with perhaps 1,000 speakers. However, most families in the community speak Toto at home. Most children learn Toto at home, although they use Bengali in school.
Anthropological Survey of India (AnSI) set out to conduct a study on language of the primitive Toto tribe, whose population has dwindled to 1,536, they did not realize that the language is more endangered than the tribe itself. Researchers and even the members of Toto community admit that the language is under threat and influence of other languages, particularly Nepali and Bengali, is increasing day by day. Despite the language lacking a script, members of the community, whose literacy rate as per sample survey carried out in 2003 was just 33.64 per cent, have penned books and poems in their language albeit in the Bengali script.
The Himalayan Languages Project is working on the first grammatical sketch of Toto. Himalayan Languages Project have arguably contributed more to advancing Tibeto-Burman linguistics than all other working scholars combined. George van Driem outlines the contributions of linguistics, archaeology and genetics to the population history of the greater Himalayan region. He emphasizes the role of genetics in the study of Tibeto-Burman linguistics.
Toto Language consists of 25 segmental Phonemes of which 19 are consonants and 6 are vowels. The phonemes of this language are as follows: Vowels: These are 6 vowel phonemes in Toto language. They can be classified horizontally into three as front unrounded, central unrounded and back rounded vowels and vertically as close, close-mid, open-mid and open.
The following minimal pairs establish the phonetics status of the vowel
/iŋ/ ‘brother in-law’
/cewa/ ‘cut’ (cloth)
/lapa/ ‘jungle betel leaf’
There are eight diphthongs realized in Toto language. These are /ei/, /ai/, /oi/, /ui/, /əi/, /eu/, /au/ and /ou/. Diphthong /ui/ occurs in all positions, /eu/ occurs initial and medial positions, /ai/, /oi/, /əi/, and /ei/ occur medial and final positions. While /ou/ and /au/ occur only in the medial positions. Furthermore, with regard to consonants, Toto has an inventory of ten obstruents, eight of which are contrastive in voicing. Toto also distinguishes the voiceless obstruents /t/ and /p/ with its aspirated equivalents /tʰ/ and /pʰ/, respectively. 
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