The Eskimo-Aleut language family consists of two quite different branches, Aleut and Eskimo. The latter consists of Yupik and Inuit languages. It is spoken from the eastern coast of Russia to Greenland. The family is thought to have developed and diverged in Alaska between 4,000 and 6,000 years ago, although recent findings in a variety of fields suggest a more complex prehistory than previously assumed. The language family shares certain characteristics, including polysynthetic word formation, an originally ergative-absolutive case system (now substantially modified in Aleut), SOV word order, and more or less similar phonological systems across the language family, involving voiceless stop and voiced fricative consonant series often in alternation, and an originally four-vowel system frequently reduced to three. The languages in the family have undergone substantial postcolonial contact effects, especially evident in (although not restricted to) loanwords from the respective colonial languages. There is extensive language documentation for all languages, although not necessarily all dialects. Most languages and dialects are severely endangered today, with the exception of Eastern Canadian Inuit and Greenlandic (Kalaallisut). There are also theoretical studies of the languages in many linguistic fields, although the languages are unevenly covered, and there are still many more studies of the phonologies and syntaxes of the respective languages than other aspects of grammar.