Historical linguistics

Historical linguistics is the study of language change.Bynon, Theodora 1977. Historical linguistics. Cambridge University Press.  It has five main concerns:
to study changes in particular languages
to discover the pre-history of languages, and group them into language families (comparative linguistics)
to develop theories about how and why language or sound changes
to describe the history of speech communities
to study the history of words, etymology.

History and development
Modern historical linguistics dates from the late 18th century. It grew out of the earlier discipline of philology, the study of ancient texts and documents dating back to antiquity.

At first, historical linguistics was comparative linguistics. The focus was on the well-known Indo-European languages, many of which had long written histories. Scholars also studied the Uralic languages, another language family for which less early written material exists.

Since then, there has been linguistic work in non-European languages, such as on the Austronesian languages and various families of Native American languages.

Comparative linguistics is now part of a discipline of historical linguistics. For Indo-European languages, comparative study is now a well-developed field. Most research is being carried out on their later development, such as the development of the modern standard varieties.Janda. Richard D. and Joseph, Brian D. (eds) 2004. The handbook of historical linguistics. Blackwell. 

Some scholars have done studies attempting to establish super-families. They have, for example, linked Indo-European, Uralic, and other families into Nostratic. Such attempts have not been accepted widely. The information needed to establish relatedness becomes thinner the farther back. The time depth of linguistic methods is limited because of chance word resemblances and variations between language groups. Scholars can trace language changes back to around 10,000 years. The dating of the various proto-languages is also difficult; several methods are available for dating, but only approximate results are possible.Trask R L. 2001. (ed) Dictionary of historical and comparative linguistics. Fitzroy Dearborn. 

 References 

Category:Branches of linguistics