Language isolate
A language isolate, in the absolute sense, is a natural language with no demonstrable genealogical relationship with other languages, one that has not been demonstrated to descend from an ancestor common with any other language. Language isolates are in effect language families consisting of a single language. Commonly cited examples include Ainu, Basque, Sumerian, Elamite, and Vedda, though in each case a minority of linguists claim to have demonstrated a relationship with other languages.
Some sources use the term "language isolate" to indicate a branch of a larger family with only one surviving member. For instance, Albanian, Armenian and Greek are commonly called Indo-European isolates. While part of the Indo-European family, they do not belong to any established branch, but instead form independent branches. Similarly, within the Romance languages, Sardinian is a relative isolate. However, without a qualifier, isolate is understood to mean having no demonstrable genetic relationship to any other known language.
Some languages once seen as isolates may be reclassified as small families. This happened with Japanese and Korean in Koreanic languages with Jeju language. The Etruscan language of Italy has long been considered an isolate, but some have proposed that it is related to the so-called Tyrsenian languages, an extinct family of closely related ancient languages proposed by Helmut Rix in 1998, including the Rhaetian language, formerly spoken in the central Alps, and the Lemnian language, formerly spoken on the Greek island of Lemnos.
Language isolates may be seen as a special case of unclassified languages that remain unclassified even after extensive efforts. 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
The term "genetic relationship" is meant in the genealogical sense of historical linguistics, which groups most languages spoken in the world today into a relatively small number of families, according to 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 proto-language that diverged into multiple languages or branches. 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, which explains the exceptional interest that these languages have received from linguists.Looking for relationships
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. Similarly, if deaf parents were to raise a group of hearing children who have no contact with others until adulthood, those children might develop an oral language among themselves and keep using it later, teaching it to their children, and so on. Eventually, it could develop into the full-fledged language of a population. With unsigned languages, this is not very likely to occur at any one time but, over the tens of thousands of years of human prehistory, the likelihood of this occurring at least a few times increases. There are also creole languages and constructed languages such as Esperanto, which do not descend directly from a single ancestor but have become the language of a population; however, they do take elements from existing languages.Extinct isolates
Caution is required when speaking of extinct languages as isolates. Despite their great age, Sumerian and Elamite can be safely classified as isolates, as the languages are well enough known that, if modern relatives existed, they would be recognizably related.However, 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 also believed by mainstream majority to be isolates, 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, the Adamorobe Sign Language in Ghana, the Urubu Sign Language in Brazil, several Mayan sign languages, 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.
List of language isolates by continent
Below is a list of known language isolates, arranged by continent, along with notes on possible relations to other languages or language families.The Status column indicates the long-term viability of the language, according to the definitions of the UNESCO Atlas of the World's Languages in Danger. "Vibrant" languages are those in full use by speakers of every generation, with consistent native acquisition by children. "Vulnerable" languages have a similarly wide base of native speakers, but a restricted use and the long-term risk of language shift. "Endangered" languages are either acquired irregularly or spoken only by older generations. "Moribund" languages have only a few remaining native speakers, with no new acquisition, highly restricted use, and near-universal bilingualism. "Extinct" languages have no native speakers, but are sufficiently documented to be classified as isolates.
Africa
With few exceptions, all of Africa's languages have been gathered into four major phyla: Afroasiatic, Niger–Congo, Nilo-Saharan and Khoisan. However, the genetic unity of some language families, like Nilo-Saharan, is questionable, and so there may be many more language families and isolates than currently accepted. Data for several African languages, like Kwadi and Kwisi, are not sufficient for classification. In addition, Jalaa, Shabo, Laal, Kujargé, and a few other languages within Nilo-Saharan and Afroasiatic-speaking areas may turn out to be isolates upon further investigation. Defaka and Ega are highly divergent languages located within Niger-Congo-speaking areas, and may also possibly be language isolates.| Language | Speakers | Status | Countries | Comments |
| Bangime | 2,000 | Vibrant | Mali | Spoken in the Bandiagara Escarpment. Used as an anti-language. |
| Hadza | 1,000 | Vulnerable | Tanzania | Spoken on the southern shore of Lake Eyasi in the southwest of Arusha Region. Once listed as an outlier among the Khoisan languages. Language use is vigorous, though there are fewer than 1,000 speakers. |
| Jalaa | Extinct | Nigeria | Strongly influenced by Dikaka, but most vocabulary is very unusual. | |
| Laal | 750 | Moribund | Chad | Spoken in three villages along the Chari River in Moyen-Chari Region. Poorly known. Also known as Gori. Possibly a distinct branch of Niger–Congo, Chadic of the Afroasiatic languages, or mixed. |
| Sandawe | 60,000 | Vibrant | Tanzania | Spoken in the northwest of Dodoma Region. Tentatively linked to the Khoe languages. |
| Shabo | 400 | Endangered | Ethiopia | Spoken in Anderaccha, Gecha, and Kaabo of the Southern Nations, Nationalities, and Peoples' Region. Linked to the Gumuz and Koman families in the proposed Komuz branch of the Nilo-Saharan languages |
Asia
Oceania
The languages of New Guinea are poorly studied, and candidates for isolate status are likely to change when more becomes known about them.| Language | Speakers | Status | Countries | Comments |
| Abinomn | 300 | Vibrant | Indonesia | Spoken in the far north of New Guinea. Also known as Bas or Foia. Language use is vigorous, despite low number of speakers. |
| Anêm ? | 800 | Vibrant | Papua New Guinea | Spoken on the northwest coast of New Britain. Perhaps related to Yélî Dnye and Ata. |
| Ata ? | 2,000 | Vibrant | Papua New Guinea | Spoken in the central highlands of New Britain. Also known as Wasi. Perhaps related to Yélî Dnye and Anem. |
| Giimbiyu ? | Extinct | Australia | Spoken in the northern part of Arnhem Land until the early 1980s. Sometimes considered a small language family consisting of Mengerrdji, Urningangk and Erre. Part of a proposal for the undemonstrated Arnhem Land language family. | |
| Kol | 4,000 | Vibrant | Papua New Guinea | Spoken in the northeastern part of New Britain. Possibly related to the poorly-known Sulka, or the Baining languages. |
| Kuot | 2,400 | Vulnerable | Papua New Guinea | Spoken on New Ireland. Also known as Panaras. |
| Malak-Malak | 10 | Moribund | Australia | Spoken in northern Australia. Often considered part of one Northern Daly family together with Tyeraity. Used to be considered genetically related to the Wagaydyic languages, but nowadays they are considered genetically distinct. |
| Murrinh-patha ? | 1,973 | Vibrant | Australia | Spoken on the eastern coast of Joseph Bonaparte Gulf in the Top End. The proposed linkage to Ngan’gityemerri in one Southern Daly family is generally accepted to be valid. |
| Ngan’gityemerri ? | 26 | Moribund | Australia | Spoken in the Top End along the Daly River. The proposed linkage to Murrinh-patha in one Southern Daly family is generally accepted to be valid. |
| Sulka | 2,500–3,000 | Vibrant | New Britain, Papua New Guinea | Possible language isolate spoken across the eastern end of New Britain. Poorly attested. |
| Tayap | >50 | Moribund | Papua New Guinea | Formerly spoken in the village of Gapun. Link to Lower Sepik languages and Torricelli languages have been explored, but the general consensus among Linguists is that it is an isolate unrelated to surrounding languages. |
| Tiwi | 2,040 | Vulnerable | Australia | Spoken in the Tiwi Islands in the Timor Sea. Traditionally Tiwi is polysynthetic, but the Tiwi spoken by younger generations is not. |
| Wagiman | 11 | Moribund | Australia | Spoken in the southern part of the Top End. May be distantly related to the Yangmanic languages, which might in turn be a member of the Macro-Gunwinyguan family, but neither link has been demonstrated. |
| Wardaman | 50 | Moribund | Australia | Spoken in the southern part of the Top End. The extinct and poorly-attested Dagoman and Yangman dialects are sometimes treated as separate languages, forming a Yangmanic family, to which Wagiman may be distantly related. Possibly a member of the Macro-Gunwinyguan family, but this has yet to be demonstrated. |