In linguistics, genetic relationship is the usual term for the relationship which exists between languages that are members of the same language family. The term genealogical relationship is sometimes used to avoid confusion with the unrelated use of the term in biological genetics. Languages that possess genetic ties with one another belong to the same linguistic grouping, known as a language family. These ties are established through use of the comparative method of linguistic analysis.
Two languages are considered to be genetically related if one is descended from the other or if both are descended from a common ancestor. For example, Italian is descended from Latin. Italian and Latin are therefore said to be genetically related. Spanish is also descended from Latin. Therefore, Spanish and Italian are genetically related. In a similar way, Danish, Swedish and Norwegian are genetically related through the North Germanic branch of the Indo-European language family.
The classification of languages into language families begins by making a list of words in the potential languages that exhibit lexical and grammatical similarities; that is, they are similar in sound and meaning. The next step is to determine how the similarities originated. There are three possibilities: convergence, borrowing and common origin. Convergence is the chance similarity of sound and meaning of a word in two different languages and "is based on the principle that a word is an arbitrary association of sound and meaning". An example of convergence is that many unrelated languages have words similar to mama and papa for 'mother' and 'father'. Borrowing results from the exchanging of words between languages in close contact with one another. Once convergence and borrowing have been eliminated as possible explanations for similarities in sound and meaning of words, the last explanation is common origin. It can be assumed that the similarities occurred due to descent from a common ancestor, and the words are known as cognates. The set of all cognates of a word is the etymology of the word.
When languages are in contact with one another, either of them may influence the other through linguistic interference such as borrowing. For example, French has influenced English, Arabic has influenced Persian, and Chinese has influenced Japanese in this way. However, such influence does not constitute (and is not a measure of) a genetic relationship between the languages concerned. Linguistic interference can occur between languages that are genetically closely related, between languages that are distantly related (like English and French, which are distantly related Indo-European languages) and between languages that have no genetic relationship.
One theory concerning genetic relationships among languages is monogenesis – the idea that all known languages, with the exceptions of creoles, pidgins and sign languages, are descendant from a single ancestral language.
A common visual representation of a language family is given by a genetic language tree. The tree model is sometimes termed a dendrogram or phylogeny. The family tree shows the relationship of the languages within in a family, much as a family tree of an individual shows their relationship with their relatives. There are criticisms to the family tree model. Critics focus mainly on the claim that the internal structure of the trees is subject to variation based on the criteria of classification. Even among those who support the family tree model, there are debates over which languages should be included in a language family. For example, within the dubious Altaic language family, there are debates over whether the Japonic and Koreanic languages should be included or not.
The wave model has been proposed as an alternative to the tree model. The wave model uses isoglosses to group language varieties; unlike in the tree model, these groups can overlap. While the tree model implies a lack of contact between languages after derivation from an ancestral form, the wave model emphasizes the relationship between languages that remain in contact, which is more realistic.
Some problems encountered by the genetic relationship group of languages include language isolates and mixed, pidgin and creole languages. Mixed languages, pidgins and creole languages constitute special genetic types of languages. They do not descend linearly or directly from a single language and have no single ancestor. Language isolates are languages that are unrelated to other languages. Each language isolate is considered to be a single language family with one language according to the Ethnologue. Including language isolates when counting language families considerably increases the number of language families.
Genetic relationship may refer to:
Genetic distance, in genetics
Genetic relationship (linguistics), in languageTree model
In historical linguistics, the tree model (also Stammbaum, genetic, or cladistic model) is a model of the evolution of languages analogous to the concept of a family tree, particularly a phylogenetic tree in the biological evolution of species. As with species, each language is assumed to have evolved from a single parent or "mother" language, with languages that share a common ancestor belonging to the same language family.
Popularized by the German linguist August Schleicher in 1853, the tree model has always been a common method of describing genetic relationships between languages since the first attempts to do so. It is central to the field of comparative linguistics, which involves using evidence from known languages and observed rules of language feature evolution to identify and describe the hypothetical proto-languages ancestral to each language family, such as Proto-Indo-European and the Indo-European languages. However, this is largely a theoretical, qualitative pursuit, and linguists have always emphasized the inherent limitations of the tree model due to the large role played by horizontal transmission in language evolution, ranging from loanwords to creole languages that have multiple mother languages. The wave model was developed in 1872 by Schleicher's student Johannes Schmidt as an alternative to the tree model that incorporates horizontal transmission.
The tree model also has the same limitations as biological taxonomy with respect to the species problem of quantizing a continuous phenomenon that includes exceptions like ring species in biology and dialect continua in language. The concept of a linkage was developed in response and refers to a group of languages that evolved from a dialect continuum rather than from linguistically isolated child languages of a single language.