Language family

A language family is a group of languages related through descent from a common ancestor, called the proto-language of that family. The term family is a metaphor borrowed from biology, with the tree model used in historical linguistics analogous to a family tree, or to phylogenetic trees of taxa used in evolutionary taxonomy. Linguists thus describe the daughter languages within a language family as being genetically related. The divergence of a proto-language into daughter languages typically occurs through geographical separation, with different regional dialects of the proto-language undergoing different language changes and thus becoming distinct languages over time. One well-known example of a language family is the Romance languages, including Spanish, French, Italian, Portuguese, Romanian, Catalan, Romansh, and many others, all of which are descended from Vulgar Latin. The Romance family itself is part of the larger Indo-European family, which includes many other languages native to Europe and South Asia, all believed to be descended from a common ancestor known as Proto-Indo-European. The Indo-European family is the largest language family in terms of number of living speakers, and the best-studied. A language family is usually said to contain at least two languages, although language isolates — languages that are not related to any other language — are occasionally referred to as families that contain one language. Conversely, there is no upper bound to the number of languages a family can contain. Some families, such as the Austronesian languages, contain over 1,000. Language families can be identified from characteristics shared amongst their languages. Sound changes are one of the strongest pieces of evidence that can be used to identify a genetic relationship because of their predictable and consistent nature, and through the comparative method can be used to reconstruct proto-languages. However, languages can also change through language contact, which can falsely...