User:Eileen Lynch/Language isolate

Language isolates are languages that cannot be classified into language families with any other languages. Basque, Burushaski, and Ainu are three of the most commonly cited language isolates, though there are many others.

A language isolate is a language that is unrelated to any others, which makes it the only language in its own language family. It is a natural language with no demonstrable genealogical (or "genetic") relationships—one that has not been demonstrated to descend from an ancestor common with any other language.

One explanation for the existence of language isolates is that they might be the last remaining branch of a larger language family. The language possibly had relatives in the past but they have since disappeared without being documented. Another explanation for language isolates is that they developed in isolation from other languages. This explanation mostly applies to sign languages that have arisen independently of other spoken or signed languages.

Some languages once seen as isolates may be reclassified as small families because their genetic relationship to other languages has been established. An example of this is Japanese which is now considered to be related to Ryukyuan languages. There is a difference between language isolates and unclassified languages, but they can be difficult to differentiate when it comes classifying extinct languages. If such efforts eventually do prove fruitful, a language previously considered an isolate may no longer be considered one, as happened with the Yanyuwa language of northern Australia, which has been placed in the Pama–Nyungan family. Since linguists do not always agree on whether a genetic relationship has been demonstrated, it is often disputed whether a language is an isolate or not.

Genetic or genealogical relationships
A language isolate is a language that has no demonstrable genealogical (or "genetic") relationship to any other known language. It is not the descendent of any ancestral language which has other known descendants or daughter languages.

The term "genetic relationship" in the sense of historical linguistics is used to group most languages spoken in the world today into a relatively small number of families, according to proof of reconstructed descent from common ancestral languages. A "genetic relationship" is a connection between languages, like similarities in vocabulary or grammar, that can be attributed to a common ancestral language that diverged into multiple daughter languages or branches. This is what makes up a language family, which is a set of languages for which sufficient evidence exists to demonstrate that they descend from a single ancestral language and are therefore genetically related. For example, English is related to other Indo-European languages and Mandarin Chinese is related to other Sino-Tibetan languages. By this criterion, each language isolate constitutes a family of its own.

In some situations, a language with no ancestor can arise. This frequently happens with sign languages—most famously in the case of Nicaraguan Sign Language, where deaf children with no language were placed together and developed a new language.

Extinct isolates
Caution is required when speaking of extinct languages as language isolates. Despite their great age, Sumerian and Elamite can be safely classified as isolates, as the languages are well enough documented that, if modern relatives existed, they would be recognizably related. A language thought to be an isolate may turn out to be related to other languages once enough material is recovered, but this is unlikely for extinct languages whose written records have not been preserved.

However, many extinct languages are very poorly attested which may lead to them being considered unclassified languages instead of language isolates. This occurs when linguists do not have enough information on a language to classify it as either a language isolate or as a part of another language family.

Isolates v. unclassified languages
Unclassified languages are different from language isolates in that they have no demonstrable genetic relationships to other languages due to a lack of sufficient data. Language isolates need to have sufficient data for comparisons with other languages through methods of historical-comparative linguistics in order to show that they do not have any demonstrable genetic relationships.

Many extinct languages are very poorly attested, and the fact that they cannot be linked to other languages may be a reflection of our poor knowledge of them. Hattic, Gutian, and Kassite are all considered unclassified languages, but their status is disputed by a minority of linguists. Many extinct languages of the Americas such as Cayuse and Majena may likewise have been isolates. A language thought to be an isolate may turn out to be relatable to other languages once enough material is recovered, but material is unlikely to be recovered if a language was not documented in writing.

Sign language isolates
A number of sign languages have arisen independently, without any ancestral language, and thus are true language isolates. The most famous of these is the Nicaraguan Sign Language, a well documented case of what has happened in schools for the deaf in many countries. In Tanzania, for example, there are seven schools for the deaf, each with its own sign language with no known connection to any other language. Sign languages have also developed outside schools, in communities with high incidences of deafness, such as Kata Kolok in Bali, and half a dozen sign languages of the hill tribes in Thailand including the Ban Khor Sign Language.

These and more are all presumed isolates or small local families, because many deaf communities are made up of people whose hearing parents do not use sign language, and have manifestly, as shown by the language itself, not borrowed their sign language from other deaf communities during the recorded history of these languages.

Reclassification
Some languages once seen as isolates may be reclassified as small families because their genetic relationship to other languages has been established. This happened with Japanese (now included in the Japonic family along with Ryukyuan languages such as Okinawan), Etruscan as part of the Tyrsenian language family, Atakapa and Akokisa, Tol and Jicaque of El Palmar, and the Xincan Guatemala language family now consisting of Chiquimulilla, Guazacapán, Jumaytepeque, and Yupiltepeque languages.