Shared innovations, acquired by borrowing or other means, are not
considered genetic and have no bearing with the language family concept.
It has been asserted, for example, that many of the more striking
features shared by Italic languages (Latin, Oscan, Umbrian, etc.) might well be "areal features". However, very similar-looking alterations in the systems of long vowels in the West Germanic languages
greatly postdate any possible notion of a proto-language innovation
(and cannot readily be regarded as "areal", either, since English and
continental West Germanic were not a linguistic area). In a similar
vein, there are many similar unique innovations in Germanic, Baltic and Slavic
that are far more likely to be areal features than traceable to a
common proto-language. But legitimate uncertainty about whether shared
innovations are areal features, coincidence, or inheritance from a
common ancestor, leads to disagreement over the proper subdivisions of
any large language family.
A sprachbund is a geographic area having several languages that feature common linguistic structures. The similarities between those languages are caused by language contact, not by chance or common origin, and are not recognized as criteria that define a language family. An example of a sprachbund would be the Indian subcontinent.
A sprachbund is a geographic area having several languages that feature common linguistic structures. The similarities between those languages are caused by language contact, not by chance or common origin, and are not recognized as criteria that define a language family. An example of a sprachbund would be the Indian subcontinent.
Contact languages
Main articles: Mixed language and Creole language
The concept of language families is based on the historical observation that languages develop dialects,
which over time may diverge into distinct languages. However,
linguistic ancestry is less clear-cut than familiar biological ancestry,
in which species do not crossbreed. It is more like the evolution of
microbes, with extensive lateral gene transfer: Quite distantly related languages may affect each other through language contact, which in extreme cases may lead to languages with no single ancestor, whether they be creoles or mixed languages. In addition, a number of sign languages have developed in isolation and appear to have no relatives at all.















