Editing Language family (section)

== Structure of a family ==
{{More citations needed section|date=May 2022}}
A language family is a [[monophyly|monophyletic]] unit; all its members derive from a common ancestor, and all descendants of that ancestor are included in the family. Thus, the term ''family'' is analogous to the biological term ''[[clade]]''. Language families can be divided into smaller phylogenetic units, sometimes referred to as "branches" or "subfamilies" of the family; for instance, the [[Germanic languages]] are a subfamily of the [[Indo-European languages|Indo-European]] family. Subfamilies share a more recent common ancestor than the common ancestor of the larger family; [[Proto-Germanic]], the common ancestor of the Germanic subfamily, was itself a descendant of [[Proto-Indo-European]], the common ancestor of the Indo-European family. Within a large family, subfamilies can be identified through "shared innovations": members of a subfamily will share features that represent retentions from their more recent common ancestor, but were not present in the overall proto-language of the larger family.

Some [[taxonomy (general)|taxonomists]] restrict the term ''family'' to a certain level, but there is little consensus on how to do so. Those who affix such labels also subdivide branches into ''groups'', and groups into ''complexes''. A top-level (i.e., the largest) family is often called a ''phylum'' or ''stock''. The closer the branches are to each other, the more closely the languages will be related. This means if a branch of a [[proto-language]] is four branches down and there is also a [[sister language]] to that fourth branch, then the two sister languages are more closely related to each other than to that common ancestral proto-language.

The term ''[[macrofamily]]'' or ''superfamily'' is sometimes applied to proposed groupings of language families whose status as phylogenetic units is generally considered to be unsubstantiated by accepted [[historical linguistics|historical linguistic]] methods.

=== Dialect continua ===
{{main|Dialect continuum}}

Some close-knit language families, and many branches within larger families, take the form of [[dialect continuum|dialect continua]] in which there are no clear-cut borders that make it possible to unequivocally identify, define, or count individual languages within the family. However, when the differences between the speech of different regions at the extremes of the continuum are so great that there is no [[mutual intelligibility]] between them, as occurs in [[Arabic]], the continuum cannot meaningfully be seen as a single language.

A speech variety may also be considered either a language or a dialect depending on social or political considerations. Thus, different sources, especially over time, can give wildly different numbers of languages within a certain family. [[Classification of the Japonic languages|Classifications of the Japonic family]], for example, range from one language (a language isolate with dialects) to nearly twenty—until the classification of [[Ryukyuan language|Ryukyuan]] as separate languages within a [[Japonic language family]] rather than dialects of Japanese, the [[Japanese language]] itself was considered a [[language isolate]] and therefore the only language in its family.

=== Isolates ===
{{main|Language isolate}}
Most of the world's languages are known to be related to others. Those that have no known relatives (or for which family relationships are only tentatively proposed) are called [[language isolate]]s, essentially language families consisting of a single language. There are an estimated 129 language isolates known today.<ref name=":0">{{cite journal|last=Campbell |first=Lyle |date=24 August 2010 |title=Language Isolates and Their History, or, What's Weird, Anyway? |journal=Annual Meeting of the Berkeley Linguistics Society |language=en |volume=36 |issue=1 |pages=16–31 |doi=10.3765/bls.v36i1.3900 |issn=2377-1666 |doi-access=free}}</ref> An example is [[Basque language|Basque]]. In general, it is assumed that language isolates have relatives or had relatives at some point in their history but at a time depth too great for linguistic comparison to recover them.

A language isolate is classified based on the fact that enough is known about the isolate to compare it genetically to other languages but no common ancestry or relationship is found with any other known language.<ref name=":0" />

A language isolated in its own branch within a family, such as [[Albanian language|Albanian]] and [[Armenian language|Armenian]] within Indo-European, is often also called an isolate, but the meaning of the word "isolate" in such cases is usually clarified with a [[Grammatical modifier|modifier]]. For instance, Albanian and Armenian may be referred to as an "Indo-European isolate". By contrast, so far as is known, the [[Basque language]] is an absolute isolate: it has not been shown to be related to any other modern language despite numerous attempts. A language may be said to be an isolate currently but not historically if related but now extinct relatives are attested. The [[Aquitanian language]], spoken in Roman times, may have been an ancestor of Basque, but it could also have been a sister language to the ancestor of Basque. In the latter case, Basque and Aquitanian would form a small family together. Ancestors are not considered to be distinct members of a family.{{citation needed|date=April 2023}}

=== Proto-languages ===
{{main|Proto-language}}
A proto-language can be thought of as a mother language (not to be confused with a [[mother tongue]]<ref>{{cite book|last=Bloomfield |first=Leonard |url=https://books.google.com/books?id=Gfrd-On5iFwC |title=Language |year=1994 |publisher=Motilal Banarsidass Publ. |isbn=81-208-1196-8}}</ref>) being the root from which all languages in the family stem. 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 in the [[list of language families]]. For example, the reconstructible common ancestor of the Indo-European language family is called ''[[Proto-Indo-European language|Proto-Indo-European]]''. Proto-Indo-European is not attested by written records and so is conjectured to have been spoken before the invention of writing.