Language family

From Wikipedia、the free encyclopedia

A language family is a group of related languages said to have descended from a common proto-language. Most languages are known to belong to language families. An accurately identified family is a phylogenetic unit; that is、all its members derive from a common ancestor. The concept of language families thus entails the concept of a historical genetic ancestor of a language、implying a gradual evolution over time of one language into another language (as opposed to sudden replacement of a language). The concept of linguistic ancestry is less clear-cut than the concept of biological ancestry、as in cases of extreme historical language contact、in particular the formation of creole languages and other types of mixed languages; it may be unclear which language should be considered the ancestor of a given language. However、these types of cases are relatively rare and most languages can be unambiguously classified into families.

The common ancestor of a language family is seldom known directly、since most languages have a relatively short recorded history. However、it is possible to recover many features of a proto-language by applying the comparative method — a reconstructive procedure worked out by 19th century linguist August Schleicher. This can demonstrate the validity of many of the proposed families listed below.

Language families can be divided into smaller phylogenetic units、conventionally referred to as branches of the family、because the history of a language family is often represented as a tree diagram. However、the term family is not restricted to any one level of this "tree"; the Germanic family、for example、is a branch of the Indo-European family. Some taxonomists restrict the term family to a certain level、but there is little consensus in how to do so. Those who affix such labels also subdivide branches into groups、and groups into complexes. The terms superfamily、phylum、and stock are applied to proposed groupings of language families whose status as phylogenetic units is generally considered to be unsubstantiated by accepted historical linguistic methods.

The common ancestor of the languages belonging to a language family is known as its proto-language. For example、the reconstructible proto-language of the Indo-European language family is called Proto-Indo-European. Proto-Indo-European is not attested by written records、since it was spoken before the invention of writing、but sometimes a proto-language can be identified with a historically known language. Thus、provincial dialects of Latin ("Vulgar Latin") gave rise to the modern Romance languages、so the Proto-Romance language is more or less identical with Latin (if not exactly with the literary Latin of the Classical writers)、and dialects of Old Norse are the proto-language of Norwegian、Swedish、Danish、Faroese and Icelandic.

Languages that cannot be reliably classified into any family are known as language isolates. A language isolated in its own branch within a family、such as Greek within Indo-European、is often also called an isolate、but such cases are usually clarified. For instance、Greek might be referred to as an Indo-European isolate. This modern isolate however is not reflected in its own history、because Greek results from the evolution from within the larger Indo-European language. On the opposite、the Basque language is a living modern language and a near perfect isolate、whose history and lexical/phonetic/syntaxic structure and history is not known and not easily associated to other languages (even if it has been influenced by Romance languages in the nearby region、like Castillian Spanish、Catalan、Occitan、and French).

Connections among and between language families are often used by anthropologists、in combination with DNA evidence and fossil evidence、to help reconstruct pre-historic migrations of peoples、and other pre-historic events、such as the spread of agriculture.